X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlfunc.pod;h=f87471b069bc65b3b559958122951ee384c16b38;hb=0ade19845bc827615a636e5c073d498c2244ec07;hp=a28487ac1dcb29a01900bd396f49a6e659d71195;hpb=3e3baf6d63945cb64e829d6e5c70a7d00f3d3d03;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index a28487a..f87471b 100644
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -52,26 +52,36 @@ nonabortive failure is generally indicated in a scalar context by
 returning the undefined value, and in a list context by returning the
 null list.
 
-Remember the following rule:
-
-=over 8
-
-=item  I<THERE IS NO GENERAL RULE FOR CONVERTING A LIST INTO A SCALAR!>
-
-=back
-
+Remember the following important rule: There is B<no rule> that relates
+the behavior of an expression in list context to its behavior in scalar
+context, or vice versa.  It might do two totally different things.
 Each operator and function decides which sort of value it would be most
 appropriate to return in a scalar context.  Some operators return the
-length of the list that would have been returned in a list context.  Some
+length of the list that would have been returned in list context.  Some
 operators return the first value in the list.  Some operators return the
 last value in the list.  Some operators return a count of successful
 operations.  In general, they do what you want, unless you want
 consistency.
 
+An named array in scalar context is quite different from what would at
+first glance appear to be a list in scalar context.  You can't get a list
+like C<(1,2,3)> into being in scalar context, because the compiler knows
+the context at compile time.  It would generate the scalar comma operator
+there, not the list construction version of the comma.  That means it
+was never a list to start with.
+
+In general, functions in Perl that serve as wrappers for system calls
+of the same name (like chown(2), fork(2), closedir(2), etc.) all return
+true when they succeed and C<undef> otherwise, as is usually mentioned
+in the descriptions below.  This is different from the C interfaces,
+which return -1 on failure.  Exceptions to this rule are wait(),
+waitpid(), and syscall().  System calls also set the special C<$!>
+variable on failure.  Other functions do not, except accidentally.
+
 =head2 Perl Functions by Category
 
 Here are Perl's functions (including things that look like
-functions, like some of the keywords and named operators)
+functions, like some keywords and named operators)
 arranged by category.  Some functions appear in more
 than one place.
 
@@ -79,117 +89,120 @@ than one place.
 
 =item Functions for SCALARs or strings
 
-chomp, chop, chr, crypt, hex, index, lc, lcfirst, length,
-oct, ord, pack, q/STRING/, qq/STRING/, reverse, rindex,
-sprintf, substr, tr///, uc, ucfirst, y///
+C<chomp>, C<chop>, C<chr>, C<crypt>, C<hex>, C<index>, C<lc>, C<lcfirst>,
+C<length>, C<oct>, C<ord>, C<pack>, C<q>/STRING/, C<qq>/STRING/, C<reverse>,
+C<rindex>, C<sprintf>, C<substr>, C<tr///>, C<uc>, C<ucfirst>, C<y>///
 
 =item Regular expressions and pattern matching
 
-m//, pos, quotemeta, s///, split, study
+C<m>//, C<pos>, C<quotemeta>, C<s>///, C<split>, C<study>
 
 =item Numeric functions
 
-abs, atan2, cos, exp, hex, int, log, oct, rand, sin, sqrt,
-srand
+C<abs>, C<atan2>, C<cos>, C<exp>, C<hex>, C<int>, C<log>, C<oct>, C<rand>,
+C<sin>, C<sqrt>, C<srand>
 
 =item Functions for real @ARRAYs
 
-pop, push, shift, splice, unshift
+C<pop>, C<push>, C<shift>, C<splice>, C<unshift>
 
 =item Functions for list data
 
-grep, join, map, qw/STRING/, reverse, sort, unpack
+C<grep>, C<join>, C<map>, C<qw>/STRING/, C<reverse>, C<sort>, C<unpack>
 
 =item Functions for real %HASHes
 
-delete, each, exists, keys, values
+C<delete>, C<each>, C<exists>, C<keys>, C<values>
 
 =item Input and output functions
 
-binmode, close, closedir, dbmclose, dbmopen, die, eof,
-fileno, flock, format, getc, print, printf, read, readdir,
-rewinddir, seek, seekdir, select, syscall, sysread, sysseek,
-syswrite, tell, telldir, truncate, warn, write
+C<binmode>, C<close>, C<closedir>, C<dbmclose>, C<dbmopen>, C<die>, C<eof>,
+C<fileno>, C<flock>, C<format>, C<getc>, C<print>, C<printf>, C<read>,
+C<readdir>, C<rewinddir>, C<seek>, C<seekdir>, C<select>, C<syscall>,
+C<sysread>, C<sysseek>, C<syswrite>, C<tell>, C<telldir>, C<truncate>,
+C<warn>, C<write>
 
 =item Functions for fixed length data or records
 
-pack, read, syscall, sysread, syswrite, unpack, vec
+C<pack>, C<read>, C<syscall>, C<sysread>, C<syswrite>, C<unpack>, C<vec>
 
 =item Functions for filehandles, files, or directories
 
-I<-X>, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link,
-lstat, mkdir, open, opendir, readlink, rename, rmdir,
-stat, symlink, umask, unlink, utime
+C<-I<X>>, C<chdir>, C<chmod>, C<chown>, C<chroot>, C<fcntl>, C<glob>,
+C<ioctl>, C<link>, C<lstat>, C<mkdir>, C<open>, C<opendir>, C<readlink>,
+C<rename>, C<rmdir>, C<stat>, C<symlink>, C<umask>, C<unlink>, C<utime>
 
 =item Keywords related to the control flow of your perl program
 
-caller, continue, die, do, dump, eval, exit, goto, last,
-next, redo, return, sub, wantarray
+C<caller>, C<continue>, C<die>, C<do>, C<dump>, C<eval>, C<exit>,
+C<goto>, C<last>, C<next>, C<redo>, C<return>, C<sub>, C<wantarray>
 
 =item Keywords related to scoping
 
-caller, import, local, my, package, use
+C<caller>, C<import>, C<local>, C<my>, C<package>, C<use>
 
 =item Miscellaneous functions
 
-defined, dump, eval, formline, local, my, reset, scalar,
-undef, wantarray
+C<defined>, C<dump>, C<eval>, C<formline>, C<local>, C<my>, C<reset>,
+C<scalar>, C<undef>, C<wantarray>
 
 =item Functions for processes and process groups
 
-alarm, exec, fork, getpgrp, getppid, getpriority, kill,
-pipe, qx/STRING/, setpgrp, setpriority, sleep, system,
-times, wait, waitpid
+C<alarm>, C<exec>, C<fork>, C<getpgrp>, C<getppid>, C<getpriority>, C<kill>,
+C<pipe>, C<qx>/STRING/, C<setpgrp>, C<setpriority>, C<sleep>, C<system>,
+C<times>, C<wait>, C<waitpid>
 
 =item Keywords related to perl modules
 
-do, import, no, package, require, use
+C<do>, C<import>, C<no>, C<package>, C<require>, C<use>
 
 =item Keywords related to classes and object-orientedness
 
-bless, dbmclose, dbmopen, package, ref, tie, tied, untie, use
+C<bless>, C<dbmclose>, C<dbmopen>, C<package>, C<ref>, C<tie>, C<tied>,
+C<untie>, C<use>
 
 =item Low-level socket functions
 
-accept, bind, connect, getpeername, getsockname,
-getsockopt, listen, recv, send, setsockopt, shutdown,
-socket, socketpair
+C<accept>, C<bind>, C<connect>, C<getpeername>, C<getsockname>,
+C<getsockopt>, C<listen>, C<recv>, C<send>, C<setsockopt>, C<shutdown>,
+C<socket>, C<socketpair>
 
 =item System V interprocess communication functions
 
-msgctl, msgget, msgrcv, msgsnd, semctl, semget, semop,
-shmctl, shmget, shmread, shmwrite
+C<msgctl>, C<msgget>, C<msgrcv>, C<msgsnd>, C<semctl>, C<semget>, C<semop>,
+C<shmctl>, C<shmget>, C<shmread>, C<shmwrite>
 
 =item Fetching user and group info
 
-endgrent, endhostent, endnetent, endpwent, getgrent,
-getgrgid, getgrnam, getlogin, getpwent, getpwnam,
-getpwuid, setgrent, setpwent
+C<endgrent>, C<endhostent>, C<endnetent>, C<endpwent>, C<getgrent>,
+C<getgrgid>, C<getgrnam>, C<getlogin>, C<getpwent>, C<getpwnam>,
+C<getpwuid>, C<setgrent>, C<setpwent>
 
 =item Fetching network info
 
-endprotoent, endservent, gethostbyaddr, gethostbyname,
-gethostent, getnetbyaddr, getnetbyname, getnetent,
-getprotobyname, getprotobynumber, getprotoent,
-getservbyname, getservbyport, getservent, sethostent,
-setnetent, setprotoent, setservent
+C<endprotoent>, C<endservent>, C<gethostbyaddr>, C<gethostbyname>,
+C<gethostent>, C<getnetbyaddr>, C<getnetbyname>, C<getnetent>,
+C<getprotobyname>, C<getprotobynumber>, C<getprotoent>,
+C<getservbyname>, C<getservbyport>, C<getservent>, C<sethostent>,
+C<setnetent>, C<setprotoent>, C<setservent>
 
 =item Time-related functions
 
-gmtime, localtime, time, times
+C<gmtime>, C<localtime>, C<time>, C<times>
 
 =item Functions new in perl5
 
-abs, bless, chomp, chr, exists, formline, glob, import, lc,
-lcfirst, map, my, no, prototype, qx, qw, readline, readpipe,
-ref, sub*, sysopen, tie, tied, uc, ucfirst, untie, use
+C<abs>, C<bless>, C<chomp>, C<chr>, C<exists>, C<formline>, C<glob>,
+C<import>, C<lc>, C<lcfirst>, C<map>, C<my>, C<no>, C<prototype>, C<qx>,
+C<qw>, C<readline>, C<readpipe>, C<ref>, C<sub*>, C<sysopen>, C<tie>,
+C<tied>, C<uc>, C<ucfirst>, C<untie>, C<use>
 
 * - C<sub> was a keyword in perl4, but in perl5 it is an
-operator which can be used in expressions.
+operator, which can be used in expressions.
 
 =item Functions obsoleted in perl5
 
-dbmclose, dbmopen
+C<dbmclose>, C<dbmopen>
 
 =back
 
@@ -197,11 +210,11 @@ dbmclose, dbmopen
 
 =over 8
 
-=item -X FILEHANDLE
+=item I<-X> FILEHANDLE
 
-=item -X EXPR
+=item I<-X> EXPR
 
-=item -X
+=item I<-X>
 
 A file test, where X is one of the letters listed below.  This unary
 operator takes one argument, either a filename or a filehandle, and
@@ -250,7 +263,7 @@ operator may be any of:
 The interpretation of the file permission operators C<-r>, C<-R>, C<-w>,
 C<-W>, C<-x>, and C<-X> is based solely on the mode of the file and the
 uids and gids of the user.  There may be other reasons you can't actually
-read, write or execute the file.  Also note that, for the superuser,
+read, write, or execute the file, such as AFS access control lists.  Also note that, for the superuser,
 C<-r>, C<-R>, C<-w>, and C<-W> always return 1, and C<-x> and C<-X> return
 1 if any execute bit is set in the mode.  Scripts run by the superuser may
 thus need to do a stat() to determine the actual mode of the
@@ -261,7 +274,7 @@ Example:
     while (<>) {
 	chop;
 	next unless -f $_;	# ignore specials
-	...
+	#...
     }
 
 Note that C<-s/a/b/> does not do a negated substitution.  Saying
@@ -270,7 +283,7 @@ following a minus are interpreted as file tests.
 
 The C<-T> and C<-B> switches work as follows.  The first block or so of the
 file is examined for odd characters such as strange control codes or
-characters with the high bit set.  If too many odd characters (E<gt>30%)
+characters with the high bit set.  If too many strange characters (E<gt>30%)
 are found, it's a C<-B> file, otherwise it's a C<-T> file.  Also, any file
 containing null in the first block is considered a binary file.  If C<-T>
 or C<-B> is used on a filehandle, the current stdio buffer is examined
@@ -332,17 +345,18 @@ and sleep() calls.
 
 If you want to use alarm() to time out a system call you need to use an
 eval/die pair.  You can't rely on the alarm causing the system call to
-fail with $! set to EINTR because Perl sets up signal handlers to
-restart system calls on some systems.  Using eval/die always works.
+fail with C<$!> set to EINTR because Perl sets up signal handlers to
+restart system calls on some systems.  Using eval/die always works,
+modulo the caveats given in L<perlipc/"Signals">.
 
     eval {
-	local $SIG{ALRM} = sub { die "alarm\n" };	# NB \n required
+	local $SIG{ALRM} = sub { die "alarm\n" };	# NB: \n required
 	alarm $timeout;
 	$nread = sysread SOCKET, $buffer, $size;
 	alarm 0;
     };
-    die if $@ && $@ ne "alarm\n";	# propagate errors
     if ($@) {
+	die unless $@ eq "alarm\n";	# propagate unexpected errors
     	# timed out
     }
     else {
@@ -374,7 +388,7 @@ translated to CR LF on output.  Binmode has no effect under Unix; in MS-DOS
 and similarly archaic systems, it may be imperative--otherwise your
 MS-DOS-damaged C library may mangle your file.  The key distinction between
 systems that need binmode and those that don't is their text file
-formats.  Systems like Unix and Plan9 that delimit lines with a single
+formats.  Systems like Unix, MacOS, and Plan9 that delimit lines with a single
 character, and that encode that character in C as '\n', do not need
 C<binmode>.  The rest need it.  If FILEHANDLE is an expression, the value
 is taken as the name of the filehandle.
@@ -388,17 +402,17 @@ an object in the CLASSNAME package--or the current package if no CLASSNAME
 is specified, which is often the case.  It returns the reference for
 convenience, because a bless() is often the last thing in a constructor.
 Always use the two-argument version if the function doing the blessing
-might be inherited by a derived class.  See L<perlobj> for more about the
-blessing (and blessings) of objects.
+might be inherited by a derived class.  See L<perltoot> and L<perlobj>
+for more about the blessing (and blessings) of objects.
 
 =item caller EXPR
 
 =item caller
 
-Returns the context of the current subroutine call.  In a scalar context,
+Returns the context of the current subroutine call.  In scalar context,
 returns the caller's package name if there is a caller, that is, if
 we're in a subroutine or eval() or require(), and the undefined value
-otherwise.  In a list context, returns
+otherwise.  In list context, returns
 
     ($package, $filename, $line) = caller;
 
@@ -460,7 +474,7 @@ VARIABLE is omitted, it chomps $_.  Example:
     while (<>) {
 	chomp;	# avoid \n on last field
 	@array = split(/:/);
-	...
+	# ...
     }
 
 You can actually chomp anything that's an lvalue, including an assignment:
@@ -486,7 +500,7 @@ Example:
     while (<>) {
 	chop;	# avoid \n on last field
 	@array = split(/:/);
-	...
+	#...
     }
 
 You can actually chop anything that's an lvalue, including an assignment:
@@ -513,13 +527,13 @@ Here's an example that looks up nonnumeric uids in the passwd file:
 
     print "User: ";
     chop($user = <STDIN>);
-    print "Files: "
+    print "Files: ";
     chop($pattern = <STDIN>);
 
     ($login,$pass,$uid,$gid) = getpwnam($user)
 	or die "$user not in passwd file";
 
-    @ary = <${pattern}>;	# expand filenames
+    @ary = glob($pattern);	# expand filenames
     chown $uid, $gid, @ary;
 
 On most systems, you are not allowed to change the ownership of the
@@ -540,40 +554,56 @@ If NUMBER is omitted, uses $_.
 
 =item chroot
 
-This function works as the system call by the same name: it makes the
+This function works like the system call by the same name: it makes the
 named directory the new root directory for all further pathnames that
-begin with a "/" by your process and all of its children.  (It doesn't
+begin with a "/" by your process and all its children.  (It doesn't
 change your current working directory, which is unaffected.)  For security
 reasons, this call is restricted to the superuser.  If FILENAME is
-omitted, does chroot to $_.
+omitted, does a chroot to $_.
 
 =item close FILEHANDLE
 
+=item close
+
 Closes the file or pipe associated with the file handle, returning TRUE
 only if stdio successfully flushes buffers and closes the system file
-descriptor.  If the file handle came from a piped open C<close> will
-additionally return FALSE if one of the other system calls involved
-fails or if the program exits with non-zero status.  (If the problem was
-that the program exited non-zero $! will be set to 0.)
-You don't have to close FILEHANDLE if you are immediately
-going to do another open() on it, because open() will close it for you.  (See
+descriptor. Closes the currently selected filehandle if the argument
+is omitted.
+
+You don't have to close FILEHANDLE if you are immediately going to do
+another open() on it, because open() will close it for you.  (See
 open().)  However, an explicit close on an input file resets the line
-counter ($.), while the implicit close done by open() does not.  Also,
-closing a pipe will wait for the process executing on the pipe to
-complete, in case you want to look at the output of the pipe
-afterwards.  Closing a pipe explicitly also puts the status value of
-the command into C<$?>.  Example:
+counter ($.), while the implicit close done by open() does not.
 
-    open(OUTPUT, '|sort >foo');	# pipe to sort
-    ...				# print stuff to output
-    close OUTPUT;		# wait for sort to finish
-    open(INPUT, 'foo');		# get sort's results
+If the file handle came from a piped open C<close> will additionally
+return FALSE if one of the other system calls involved fails or if the
+program exits with non-zero status.  (If the only problem was that the
+program exited non-zero $! will be set to 0.)  Also, closing a pipe 
+waits for the process executing on the pipe to complete, in case you
+want to look at the output of the pipe afterwards.  Closing a pipe
+explicitly also puts the exit status value of the command into C<$?>.
 
-FILEHANDLE may be an expression whose value gives the real filehandle name.
+Example:
+
+    open(OUTPUT, '|sort >foo')  # pipe to sort
+        or die "Can't start sort: $!";
+    #...			# print stuff to output
+    close OUTPUT		# wait for sort to finish
+        or warn $! ? "Error closing sort pipe: $!"
+                   : "Exit status $? from sort";
+    open(INPUT, 'foo')		# get sort's results
+        or die "Can't open 'foo' for input: $!";
+
+FILEHANDLE may be an expression whose value can be used as an indirect
+filehandle, usually the real filehandle name.
 
 =item closedir DIRHANDLE
 
-Closes a directory opened by opendir().
+Closes a directory opened by opendir() and returns the success of that
+system call.
+
+DIRHANDLE may be an expression whose value can be used as an indirect
+dirhandle, usually the real dirhandle name.
 
 =item connect SOCKET,NAME
 
@@ -592,9 +622,28 @@ it can be used to increment a loop variable, even when the loop has been
 continued via the C<next> statement (which is similar to the C C<continue>
 statement).
 
+C<last>, C<next>, or C<redo> may appear within a C<continue>
+block. C<last> and C<redo> will behave as if they had been executed within
+the main block. So will C<next>, but since it will execute a C<continue>
+block, it may be more entertaining.
+
+    while (EXPR) {
+	### redo always comes here
+	do_something;
+    } continue {
+	### next always comes here
+	do_something_else;
+	# then back the top to re-check EXPR
+    }
+    ### last always comes here
+
+Omitting the C<continue> section is semantically equivalent to using an
+empty one, logically enough. In that case, C<next> goes directly back
+to check the condition at the top of the loop.
+
 =item cos EXPR
 
-Returns the cosine of EXPR (expressed in radians).  If EXPR is omitted
+Returns the cosine of EXPR (expressed in radians).  If EXPR is omitted,
 takes cosine of $_.
 
 For the inverse cosine operation, you may use the POSIX::acos()
@@ -633,7 +682,7 @@ their own password:
 	print "ok\n";
     }
 
-Of course, typing in your own password to whomever asks you
+Of course, typing in your own password to whoever asks you
 for it is unwise.
 
 =item dbmclose HASH
@@ -646,7 +695,7 @@ Breaks the binding between a DBM file and a hash.
 
 [This function has been superseded by the tie() function.]
 
-This binds a dbm(3), ndbm(3), sdbm(3), gdbm(), or Berkeley DB file to a
+This binds a dbm(3), ndbm(3), sdbm(3), gdbm(3), or Berkeley DB file to a
 hash.  HASH is the name of the hash.  (Unlike normal open, the first
 argument is I<NOT> a filehandle, even though it looks like one).  DBNAME
 is the name of the database (without the F<.dir> or F<.pag> extension if
@@ -662,8 +711,8 @@ variables, not set them.  If you want to test whether you can write,
 either use file tests or try setting a dummy hash entry inside an eval(),
 which will trap the error.
 
-Note that functions such as keys() and values() may return huge array
-values when used on large DBM files.  You may prefer to use the each()
+Note that functions such as keys() and values() may return huge lists
+when used on large DBM files.  You may prefer to use the each()
 function to iterate over large DBM files.  Example:
 
     # print out history file offsets
@@ -695,10 +744,10 @@ doesn't I<necessarily> indicate an exceptional condition: pop()
 returns C<undef> when its argument is an empty array, I<or> when the
 element to return happens to be C<undef>.
 
-You may also use defined() to check whether a subroutine exists.  On
-the other hand, use of defined() upon aggregates (hashes and arrays)
-is not guaranteed to produce intuitive results, and should probably be
-avoided.
+You may also use defined() to check whether a subroutine exists, by
+saying C<defined &func> without parentheses.  On the other hand, use
+of defined() upon aggregates (hashes and arrays) is not guaranteed to
+produce intuitive results, and should probably be avoided.
 
 When used on a hash element, it tells you whether the value is defined,
 not whether the key exists in the hash.  Use L</exists> for the latter
@@ -719,7 +768,7 @@ defined values.  For example, if you say
 
     "ab" =~ /a(.*)b/;
 
-the pattern match succeeds, and $1 is defined, despite the fact that it
+The pattern match succeeds, and $1 is defined, despite the fact that it
 matched "nothing".  But it didn't really match nothing--rather, it
 matched something that happened to be 0 characters long.  This is all
 very above-board and honest.  When a function returns an undefined value,
@@ -738,11 +787,12 @@ should instead use a simple test for size:
     if (%a_hash)   { print "has hash members\n"   }
 
 Using undef() on these, however, does clear their memory and then report
-them as not defined anymore, but you shoudln't do that unless you don't
+them as not defined anymore, but you shouldn't do that unless you don't
 plan to use them again, because it saves time when you load them up
-again to have memory already ready to be filled.
+again to have memory already ready to be filled.  The normal way to 
+free up space used by an aggregate is to assign the empty list.
 
-This counterintuitive behaviour of defined() on aggregates may be
+This counterintuitive behavior of defined() on aggregates may be
 changed, fixed, or broken in a future release of Perl.
 
 See also L</undef>, L</exists>, L</ref>.
@@ -766,20 +816,20 @@ And so does this:
 
     delete @HASH{keys %HASH}
 
-(But both of these are slower than the undef() command.)  Note that the
-EXPR can be arbitrarily complicated as long as the final operation is a
-hash element lookup or hash slice:
+(But both of these are slower than just assigning the empty list, or
+using undef().)  Note that the EXPR can be arbitrarily complicated as
+long as the final operation is a hash element lookup or hash slice:
 
     delete $ref->[$x][$y]{$key};
     delete @{$ref->[$x][$y]}{$key1, $key2, @morekeys};
 
 =item die LIST
 
-Outside of an eval(), prints the value of LIST to C<STDERR> and exits with
+Outside an eval(), prints the value of LIST to C<STDERR> and exits with
 the current value of C<$!> (errno).  If C<$!> is 0, exits with the value of
 C<($? E<gt>E<gt> 8)> (backtick `command` status).  If C<($? E<gt>E<gt> 8)>
 is 0, exits with 255.  Inside an eval(), the error message is stuffed into
-C<$@>, and the eval() is terminated with the undefined value; this makes
+C<$@> and the eval() is terminated with the undefined value.  This makes
 die() the way to raise an exception.
 
 Equivalent examples:
@@ -803,11 +853,28 @@ produce, respectively
 
 See also exit() and warn().
 
-You can arrange for a callback to be called just before the die() does
+If LIST is empty and $@ already contains a value (typically from a
+previous eval) that value is reused after appending "\t...propagated".
+This is useful for propagating exceptions:
+
+    eval { ... };
+    die unless $@ =~ /Expected exception/;
+
+If $@ is empty then the string "Died" is used.
+
+You can arrange for a callback to be run just before the die() does
 its deed, by setting the C<$SIG{__DIE__}> hook.  The associated handler
 will be called with the error text and can change the error message, if
-it sees fit, by calling die() again.  See L<perlvar> for details on
-setting C<%SIG> entries, and eval() for some examples.
+it sees fit, by calling die() again.  See L<perlvar/$SIG{expr}> for details on
+setting C<%SIG> entries, and L<"eval BLOCK"> for some examples.
+
+Note that the C<$SIG{__DIE__}> hook is called even inside eval()ed
+blocks/strings.  If one wants the hook to do nothing in such
+situations, put
+
+	die @_ if $^S;
+
+as the first line of the handler (see L<perlvar/$^S>).
 
 =item do BLOCK
 
@@ -830,19 +897,33 @@ from a Perl subroutine library.
 
 is just like
 
-    eval `cat stat.pl`;
+    scalar eval `cat stat.pl`;
 
-except that it's more efficient, more concise, keeps track of the
+except that it's more efficient and concise, keeps track of the
 current filename for error messages, and searches all the B<-I>
 libraries if the file isn't in the current directory (see also the @INC
-array in L<perlvar/Predefined Names>).  It's the same, however, in that it does
+array in L<perlvar/Predefined Names>).  It is also different in how
+code evaluated with C<do FILENAME> doesn't see lexicals in the enclosing
+scope like C<eval STRING> does.  It's the same, however, in that it does
 reparse the file every time you call it, so you probably don't want to
 do this inside a loop.
 
 Note that inclusion of library modules is better done with the
-use() and require() operators, which also do error checking
+use() and require() operators, which also do automatic error checking
 and raise an exception if there's a problem.
 
+You might like to use C<do> to read in a program configuration
+file.  Manual error checking can be done this way:
+
+    # read in config files: system first, then user 
+    for $file ('/share/prog/defaults.rc", "$ENV{HOME}/.someprogrc") {
+	unless ($return = do $file) {
+	    warn "couldn't parse $file: $@"         if $@;
+	    warn "couldn't do $file: $!"            unless defined $return;
+	    warn "couldn't run $file"               unless $return;
+	}
+    }
+
 =item dump LABEL
 
 This causes an immediate core dump.  Primarily this is so that you can
@@ -851,7 +932,7 @@ after having initialized all your variables at the beginning of the
 program.  When the new binary is executed it will begin by executing a
 C<goto LABEL> (with all the restrictions that C<goto> suffers).  Think of
 it as a goto with an intervening core dump and reincarnation.  If LABEL
-is omitted, restarts the program from the top.  WARNING: any files
+is omitted, restarts the program from the top.  WARNING: Any files
 opened at the time of the dump will NOT be open any more when the
 program is reincarnated, with possible resulting confusion on the part
 of Perl.  See also B<-u> option in L<perlrun>.
@@ -876,18 +957,22 @@ Example:
     QUICKSTART:
     Getopt('f');
 
+This operator is largely obsolete, partly because it's very hard to 
+convert a core file into an executable, and because the real perl-to-C
+compiler has superseded it.
+
 =item each HASH
 
-When called in a list context, returns a 2-element array consisting of the
+When called in list context, returns a 2-element list consisting of the
 key and value for the next element of a hash, so that you can iterate over
-it.  When called in a scalar context, returns the key for only the next
+it.  When called in scalar context, returns the key for only the "next"
 element in the hash.  (Note: Keys may be "0" or "", which are logically
 false; you may wish to avoid constructs like C<while ($k = each %foo) {}>
 for this reason.)
 
 Entries are returned in an apparently random order.  When the hash is
 entirely read, a null array is returned in list context (which when
-assigned produces a FALSE (0) value), and C<undef> is returned in a
+assigned produces a FALSE (0) value), and C<undef> in
 scalar context.  The next call to each() after that will start iterating
 again.  There is a single iterator for each hash, shared by all each(),
 keys(), and values() function calls in the program; it can be reset by
@@ -912,14 +997,14 @@ See also keys() and values().
 
 Returns 1 if the next read on FILEHANDLE will return end of file, or if
 FILEHANDLE is not open.  FILEHANDLE may be an expression whose value
-gives the real filehandle name.  (Note that this function actually
-reads a character and then ungetc()s it, so it is not very useful in an
+gives the real filehandle.  (Note that this function actually
+reads a character and then ungetc()s it, so isn't very useful in an
 interactive context.)  Do not read from a terminal file (or call
 C<eof(FILEHANDLE)> on it) after end-of-file is reached.  Filetypes such
 as terminals may lose the end-of-file condition if you do.
 
 An C<eof> without an argument uses the last file read as argument.
-Empty parentheses () may be used to indicate the pseudo file formed of
+Using C<eof()> with empty parentheses is very different.  It indicates the pseudo file formed of
 the files listed on the command line, i.e., C<eof()> is reasonable to
 use inside a C<while (E<lt>E<gt>)> loop to detect the end of only the
 last file.  Use C<eof(ARGV)> or eof without the parentheses to test
@@ -927,13 +1012,15 @@ I<EACH> file in a while (E<lt>E<gt>) loop.  Examples:
 
     # reset line numbering on each input file
     while (<>) {
+	next if /^\s*#/;	# skip comments 
 	print "$.\t$_";
-	close(ARGV) if (eof);	# Not eof().
+    } continue {
+	close ARGV  if eof;	# Not eof()!
     }
 
     # insert dashes just before last line of last file
     while (<>) {
-	if (eof()) {
+	if (eof()) {		# check for end of current file
 	    print "--------------\n";
 	    close(ARGV);	# close or break; is needed if we
 				# are reading from the terminal
@@ -942,28 +1029,45 @@ I<EACH> file in a while (E<lt>E<gt>) loop.  Examples:
     }
 
 Practical hint: you almost never need to use C<eof> in Perl, because the
-input operators return undef when they run out of data.
+input operators return false values when they run out of data, or if there
+was an error.
 
 =item eval EXPR
 
 =item eval BLOCK
 
-EXPR is parsed and executed as if it were a little Perl program.  It
-is executed in the context of the current Perl program, so that any
+In the first form, the return value of EXPR is parsed and executed as if it
+were a little Perl program.  The value of the expression (which is itself
+determined within scalar context) is first parsed, and if there weren't any
+errors, executed in the context of the current Perl program, so that any
 variable settings or subroutine and format definitions remain afterwards.
-The value returned is the value of the last expression evaluated, or a
-return statement may be used, just as with subroutines.  The last
-expression is evaluated in scalar or array context, depending on the
-context of the eval.
+Note that the value is parsed every time the eval executes.  If EXPR is
+omitted, evaluates C<$_>.  This form is typically used to delay parsing
+and subsequent execution of the text of EXPR until run time.
+
+In the second form, the code within the BLOCK is parsed only once--at the
+same time the code surrounding the eval itself was parsed--and executed
+within the context of the current Perl program.  This form is typically
+used to trap exceptions more efficiently than the first (see below), while
+also providing the benefit of checking the code within BLOCK at compile
+time.
+
+The final semicolon, if any, may be omitted from the value of EXPR or within
+the BLOCK.
+
+In both forms, the value returned is the value of the last expression
+evaluated inside the mini-program; a return statement may be also used, just
+as with subroutines.  The expression providing the return value is evaluated
+in void, scalar, or list context, depending on the context of the eval itself.
+See L</wantarray> for more on how the evaluation context can be determined.
 
 If there is a syntax error or runtime error, or a die() statement is
 executed, an undefined value is returned by eval(), and C<$@> is set to the
 error message.  If there was no error, C<$@> is guaranteed to be a null
-string.  If EXPR is omitted, evaluates C<$_>.  The final semicolon, if
-any, may be omitted from the expression.  Beware that using eval()
-neither silences perl from printing warnings to STDERR, nor does it
-stuff the text of warning messages into C<$@>.  To do either of those,
-you have to use the C<$SIG{__WARN__}> facility.  See warn() and L<perlvar>.
+string.  Beware that using eval() neither silences perl from printing
+warnings to STDERR, nor does it stuff the text of warning messages into C<$@>.
+To do either of those, you have to use the C<$SIG{__WARN__}> facility.  See
+L</warn> and L<perlvar>.
 
 Note that, because eval() traps otherwise-fatal errors, it is useful for
 determining whether a particular feature (such as socket() or symlink())
@@ -982,7 +1086,7 @@ Examples:
     eval '$answer = $a / $b'; warn $@ if $@;
 
     # a compile-time error
-    eval { $answer = };
+    eval { $answer = };			# WRONG
 
     # a run-time error
     eval '$answer =';	# sets $@
@@ -1001,8 +1105,8 @@ die() again, which has the effect of changing their error messages:
     # __DIE__ hooks may modify error messages
     {
        local $SIG{'__DIE__'} = sub { (my $x = $_[0]) =~ s/foo/bar/g; die $x };
-       eval { die "foo foofs here" };
-       print $@ if $@;                # prints "bar barfs here"
+       eval { die "foo lives here" };
+       print $@ if $@;                # prints "bar lives here"
     }
 
 With an eval(), you should be especially careful to remember what's
@@ -1014,7 +1118,7 @@ being looked at when:
     eval '$x';		# CASE 3
     eval { $x };	# CASE 4
 
-    eval "\$$x++"	# CASE 5
+    eval "\$$x++";	# CASE 5
     $$x++;		# CASE 6
 
 Cases 1 and 2 above behave identically: they run the code contained in
@@ -1030,19 +1134,32 @@ in case 6.
 
 =item exec LIST
 
-The exec() function executes a system command I<AND NEVER RETURNS>,
-unless the command does not exist and is executed directly instead of
-via C</bin/sh -c> (see below).  Use system() instead of exec() if you
-want it to return.
-
-If there is more than one argument in LIST, or if LIST is an array with
-more than one value, calls execvp(3) with the arguments in LIST.  If
-there is only one scalar argument, the argument is checked for shell
-metacharacters.  If there are any, the entire argument is passed to
-C</bin/sh -c> for parsing.  If there are none, the argument is split
-into words and passed directly to execvp(), which is more efficient.
-Note: exec() and system() do not flush your output buffer, so you may
-need to set C<$|> to avoid lost output.  Examples:
+=item exec PROGRAM LIST
+
+The exec() function executes a system command I<AND NEVER RETURNS> -
+use system() instead of exec() if you want it to return. It fails and
+returns FALSE only if the command does not exist I<and> it is executed
+directly instead of via your system's command shell (see below).
+
+Since it's a common mistake to use system() instead of exec(), Perl
+warns you if there is a following statement which isn't die(), warn(),
+or exit() (if C<-w> is set  -  but you always do that).   If you
+I<really> want to follow an exec() with some other statement, you
+can use one of these styles to avoid the warning:
+
+    exec ('foo')   or print STDERR "couldn't exec foo: $!";
+    { exec ('foo') }; print STDERR "couldn't exec foo: $!";
+
+If there is more than one argument in LIST, or if LIST is an array
+with more than one value, calls execvp(3) with the arguments in LIST.
+If there is only one scalar argument or an array with one element in it,
+the argument is checked for shell metacharacters, and if there are any,
+the entire argument is passed to the system's command shell for parsing
+(this is C</bin/sh -c> on Unix platforms, but varies on other platforms).
+If there are no shell metacharacters in the argument, it is split into
+words and passed directly to execvp(), which is more efficient.  Note:
+exec() and system() do not flush your output buffer, so you may need to
+set C<$|> to avoid lost output.  Examples:
 
     exec '/bin/echo', 'Your arguments are: ', @ARGV;
     exec "sort $outfile | uniq";
@@ -1061,6 +1178,25 @@ or, more directly,
 
     exec {'/bin/csh'} '-sh';	# pretend it's a login shell
 
+When the arguments get executed via the system shell, results will
+be subject to its quirks and capabilities.  See L<perlop/"`STRING`">
+for details.
+
+Using an indirect object with C<exec> or C<system> is also more secure.
+This usage forces interpretation of the arguments as a multivalued list,
+even if the list had just one argument.  That way you're safe from the
+shell expanding wildcards or splitting up words with whitespace in them.
+
+    @args = ( "echo surprise" );
+
+    system @args;               # subject to shell escapes if @args == 1
+    system { $args[0] } @args;  # safe even with one-arg list
+
+The first version, the one without the indirect object, ran the I<echo>
+program, passing it C<"surprise"> an argument.  The second version
+didn't--it tried to run a program literally called I<"echo surprise">,
+didn't find it, and set C<$?> to a non-zero value indicating failure.
+
 =item exists EXPR
 
 Returns TRUE if the specified hash key exists in its hash array, even
@@ -1076,7 +1212,13 @@ it exists, but the reverse doesn't necessarily hold true.
 Note that the EXPR can be arbitrarily complicated as long as the final
 operation is a hash key lookup:
 
-    if (exists $ref->[$x][$y]{$key}) { ... }
+    if (exists $ref->{"A"}{"B"}{$key}) { ... }
+
+Although the last element will not spring into existence just because its
+existence was tested, intervening ones will.  Thus C<$ref-E<gt>{"A"}>
+C<$ref-E<gt>{"B"}> will spring into existence due to the existence
+test for a $key element.  This autovivification may be fixed in a later
+release.
 
 =item exit EXPR
 
@@ -1097,6 +1239,8 @@ You shouldn't use exit() to abort a subroutine if there's any chance that
 someone might want to trap whatever error happened.  Use die() instead,
 which can be trapped by an eval().
 
+All C<END{}> blocks are run at exit time.  See L<perlsub> for details.
+
 =item exp EXPR
 
 =item exp
@@ -1110,19 +1254,37 @@ Implements the fcntl(2) function.  You'll probably have to say
 
     use Fcntl;
 
-first to get the correct function definitions.  Argument processing and
-value return works just like ioctl() below.  Note that fcntl() will produce
-a fatal error if used on a machine that doesn't implement fcntl(2).
+first to get the correct constant definitions.  Argument processing and
+value return works just like ioctl() below.  
 For example:
 
     use Fcntl;
-    fcntl($filehandle, F_GETLK, $packed_return_buffer);
+    fcntl($filehandle, F_GETFL, $packed_return_buffer)
+	or die "can't fcntl F_GETFL: $!";
+
+You don't have to check for C<defined> on the return from 
+fnctl.  Like ioctl, it maps a 0 return from the system
+call into "0 but true" in Perl.  This string is true in 
+boolean context and 0 in numeric context.  It is also 
+exempt from the normal B<-w> warnings on improper numeric
+conversions.
+
+Note that fcntl() will produce a fatal error if used on a machine that
+doesn't implement fcntl(2).
 
 =item fileno FILEHANDLE
 
 Returns the file descriptor for a filehandle.  This is useful for
-constructing bitmaps for select().  If FILEHANDLE is an expression, the
-value is taken as the name of the filehandle.
+constructing bitmaps for select() and low-level POSIX tty-handling
+operations.  If FILEHANDLE is an expression, the value is taken as 
+an indirect filehandle, generally its name. 
+
+You can use this to find out whether two handles refer to the 
+same underlying descriptor:
+
+    if (fileno(THIS) == fileno(THAT)) {
+	print "THIS and THAT are dups\n";
+    } 
 
 =item flock FILEHANDLE,OPERATION
 
@@ -1132,6 +1294,13 @@ that doesn't implement flock(2), fcntl(2) locking, or lockf(3).  flock()
 is Perl's portable file locking interface, although it locks only entire
 files, not records.
 
+On many platforms (including most versions or clones of Unix), locks
+established by flock() are B<merely advisory>.  Such discretionary locks
+are more flexible, but offer fewer guarantees.  This means that files
+locked with flock() may be modified by programs that do not also use
+flock().  Windows NT and OS/2 are among the platforms which
+enforce mandatory locking.  See your local documentation for details.
+
 OPERATION is one of LOCK_SH, LOCK_EX, or LOCK_UN, possibly combined with
 LOCK_NB.  These constants are traditionally valued 1, 2, 8 and 4, but
 you can use the symbolic names if import them from the Fcntl module,
@@ -1183,8 +1352,9 @@ See also L<DB_File> for other flock() examples.
 
 =item fork
 
-Does a fork(2) system call.  Returns the child pid to the parent process
-and 0 to the child process, or C<undef> if the fork is unsuccessful.
+Does a fork(2) system call.  Returns the child pid to the parent process,
+0 to the child process, or C<undef> if the fork is unsuccessful.
+
 Note: unflushed buffers remain unflushed in both processes, which means
 you may need to set C<$|> ($AUTOFLUSH in English) or call the autoflush()
 method of IO::Handle to avoid duplicate output.
@@ -1214,12 +1384,12 @@ moribund children.
 
 Note that if your forked child inherits system file descriptors like
 STDIN and STDOUT that are actually connected by a pipe or socket, even
-if you exit, the remote server (such as, say, httpd or rsh) won't think
+if you exit, then the remote server (such as, say, httpd or rsh) won't think
 you're done.  You should reopen those to /dev/null if it's any issue.
 
 =item format
 
-Declare a picture format with use by the write() function.  For
+Declare a picture format for use by the write() function.  For
 example:
 
     format Something =
@@ -1234,10 +1404,9 @@ example:
 
 See L<perlform> for many details and examples.
 
-
 =item formline PICTURE,LIST
 
-This is an internal function used by C<format>s, though you may call it
+This is an internal function used by C<format>s, though you may call it,
 too.  It formats (see L<perlform>) a list of values according to the
 contents of PICTURE, placing the output into the format output
 accumulator, C<$^A> (or $ACCUMULATOR in English).
@@ -1259,9 +1428,10 @@ formline() always returns TRUE.  See L<perlform> for other examples.
 =item getc
 
 Returns the next character from the input file attached to FILEHANDLE,
-or a null string at end of file.  If FILEHANDLE is omitted, reads from STDIN.
-This is not particularly efficient.  It cannot be used to get unbuffered
-single-characters, however.  For that, try something more like:
+or the undefined value at end of file, or if there was an error.  If
+FILEHANDLE is omitted, reads from STDIN.  This is not particularly
+efficient.  It cannot be used to get unbuffered single-characters,
+however.  For that, try something more like:
 
     if ($BSD_STYLE) {
 	system "stty cbreak </dev/tty >/dev/tty 2>&1";
@@ -1284,14 +1454,15 @@ Determination of whether $BSD_STYLE should be set
 is left as an exercise to the reader.
 
 The POSIX::getattr() function can do this more portably on systems
-alleging POSIX compliance.
+purporting POSIX compliance.
 See also the C<Term::ReadKey> module from your nearest CPAN site;
 details on CPAN can be found on L<perlmod/CPAN>.
 
 =item getlogin
 
-Returns the current login from F</etc/utmp>, if any.  If null, use
-getpwuid().
+Implements the C library function of the same name, which on most
+systems returns the current login from F</etc/utmp>, if any.  If null,
+use getpwuid().
 
     $login = getlogin || getpwuid($<) || "Kilroy";
 
@@ -1388,11 +1559,11 @@ machine that doesn't implement getpriority(2).
 =item endservent
 
 These routines perform the same functions as their counterparts in the
-system library.  Within a list context, the return values from the
+system library.  In list context, the return values from the
 various get routines are as follows:
 
     ($name,$passwd,$uid,$gid,
-       $quota,$comment,$gcos,$dir,$shell) = getpw*
+       $quota,$comment,$gcos,$dir,$shell,$expire) = getpw*
     ($name,$passwd,$gid,$members) = getgr*
     ($name,$aliases,$addrtype,$length,@addrs) = gethost*
     ($name,$aliases,$addrtype,$net) = getnet*
@@ -1401,17 +1572,33 @@ various get routines are as follows:
 
 (If the entry doesn't exist you get a null list.)
 
-Within a scalar context, you get the name, unless the function was a
+In scalar context, you get the name, unless the function was a
 lookup by name, in which case you get the other thing, whatever it is.
 (If the entry doesn't exist you get the undefined value.)  For example:
 
-    $uid = getpwnam
-    $name = getpwuid
-    $name = getpwent
-    $gid = getgrnam
-    $name = getgrgid
-    $name = getgrent
-    etc.
+    $uid   = getpwnam($name);
+    $name  = getpwuid($num);
+    $name  = getpwent();
+    $gid   = getgrnam($name);
+    $name  = getgrgid($num;
+    $name  = getgrent();
+    #etc.
+
+In I<getpw*()> the fields $quota, $comment, and $expire are special
+cases in the sense that in many systems they are unsupported.  If the
+$quota is unsupported, it is an empty scalar.  If it is supported, it
+usually encodes the disk quota.  If the $comment field is unsupported,
+it is an empty scalar.  If it is supported it usually encodes some
+administrative comment about the user.  In some systems the $quota
+field may be $change or $age, fields that have to do with password
+aging.  In some systems the $comment field may be $class.  The $expire
+field, if present, encodes the expiration period of the account or the
+password.  For the availability and the exact meaning of these fields
+in your system, please consult your getpwnam(3) documentation and your
+<pwd.h> file.  You can also find out from within Perl which meaning
+your $quota and $comment fields have and whether you have the $expire
+field by using the Config module and the values d_pwquota, d_pwage,
+d_pwchange, d_pwcomment, and d_pwexpire.
 
 The $members value returned by I<getgr*()> is a space separated list of
 the login names of the members of the group.
@@ -1425,6 +1612,20 @@ by saying something like:
 
     ($a,$b,$c,$d) = unpack('C4',$addr[0]);
 
+If you get tired of remembering which element of the return list contains
+which return value, by-name interfaces are also provided in modules:
+File::stat, Net::hostent, Net::netent, Net::protoent, Net::servent,
+Time::gmtime, Time::localtime, and User::grent.  These override the
+normal built-in, replacing them with versions that return objects with
+the appropriate names for each field.  For example:
+
+   use File::stat;
+   use User::pwent;
+   $is_his = (stat($filename)->uid == pwent($whoever)->uid);
+
+Even though it looks like they're the same method calls (uid), 
+they aren't, because a File::stat object is different from a User::pwent object.
+
 =item getsockname SOCKET
 
 Returns the packed sockaddr address of this end of the SOCKET connection.
@@ -1435,13 +1636,13 @@ Returns the packed sockaddr address of this end of the SOCKET connection.
 
 =item getsockopt SOCKET,LEVEL,OPTNAME
 
-Returns the socket option requested, or undefined if there is an error.
+Returns the socket option requested, or undef if there is an error.
 
 =item glob EXPR
 
 =item glob
 
-Returns the value of EXPR with filename expansions such as a shell would
+Returns the value of EXPR with filename expansions such as the standard Unix shell /bin/sh would
 do.  This is the internal function implementing the C<E<lt>*.cE<gt>>
 operator, but you can use it directly.  If EXPR is omitted, $_ is used.
 The C<E<lt>*.cE<gt>> operator is discussed in more detail in
@@ -1464,7 +1665,7 @@ years since 1900, I<not> simply the last two digits of the year.
 
 If EXPR is omitted, does C<gmtime(time())>.
 
-In a scalar context, returns the ctime(3) value:
+In scalar context, returns the ctime(3) value:
 
     $now_string = gmtime;  # e.g., "Thu Oct 13 04:54:34 1994"
 
@@ -1524,10 +1725,13 @@ Note that, because $_ is a reference into the list value, it can be used
 to modify the elements of the array.  While this is useful and
 supported, it can cause bizarre results if the LIST is not a named
 array.  Similarly, grep returns aliases into the original list,
-much like the way that L<Foreach Loops>'s index variable aliases the list
+much like the way that a for loops's index variable aliases the list
 elements.  That is, modifying an element of a list returned by grep
+(for example, in a C<foreach>, C<map> or another C<grep>)
 actually modifies the element in the original list.
 
+See also L</map> for an array composed of the results of the BLOCK or EXPR.
+
 =item hex EXPR
 
 =item hex
@@ -1541,7 +1745,7 @@ see L</oct>.)  If EXPR is omitted, uses $_.
 
 =item import
 
-There is no builtin import() function.  It is merely an ordinary
+There is no builtin import() function.  It is just an ordinary
 method (subroutine) defined (or inherited) by modules that wish to export
 names to another module.  The use() function calls the import() method
 for the package used.  See also L</use()>, L<perlmod>, and L<Exporter>.
@@ -1561,6 +1765,10 @@ one less than the base, ordinarily -1.
 =item int
 
 Returns the integer portion of EXPR.  If EXPR is omitted, uses $_.
+You should not use this for rounding, because it truncates
+towards 0, and because machine representations of floating point
+numbers can sometimes produce counterintuitive results.  Usually sprintf() or printf(),
+or the POSIX::floor or POSIX::ceil functions, would serve you better.
 
 =item ioctl FILEHANDLE,FUNCTION,SCALAR
 
@@ -1571,7 +1779,7 @@ Implements the ioctl(2) function.  You'll probably have to say
 first to get the correct function definitions.  If F<ioctl.ph> doesn't
 exist or doesn't have the correct definitions you'll have to roll your
 own, based on your C header files such as F<E<lt>sys/ioctl.hE<gt>>.
-(There is a Perl script called B<h2ph> that comes with the Perl kit which
+(There is a Perl script called B<h2ph> that comes with the Perl kit that
 may help you in this, but it's nontrivial.)  SCALAR will be read and/or
 written depending on the FUNCTION--a pointer to the string value of SCALAR
 will be passed as the third argument of the actual ioctl call.  (If SCALAR
@@ -1607,6 +1815,9 @@ system:
     ($retval = ioctl(...)) || ($retval = -1);
     printf "System returned %d\n", $retval;
 
+The special string "0 but true" is excempt from B<-w> complaints
+about improper numeric conversions.
+
 =item join EXPR,LIST
 
 Joins the separate strings of LIST into a single string with
@@ -1619,8 +1830,8 @@ See L<perlfunc/split>.
 
 =item keys HASH
 
-Returns a normal array consisting of all the keys of the named hash.  (In
-a scalar context, returns the number of keys.)  The keys are returned in
+Returns a list consisting of all the keys of the named hash.  (In a
+scalar context, returns the number of keys.)  The keys are returned in
 an apparently random order, but it is the same order as either the
 values() or each() function produces (given that the hash has not been
 modified).  As a side effect, it resets HASH's iterator.
@@ -1642,7 +1853,7 @@ or how about sorted by key:
 To sort an array by value, you'll need to use a C<sort> function.
 Here's a descending numeric sort of a hash by its values:
 
-    foreach $key (sort { $hash{$b} <=> $hash{$a} } keys %hash)) {
+    foreach $key (sort { $hash{$b} <=> $hash{$a} } keys %hash) {
 	printf "%4d %s\n", $hash{$key}, $key;
     }
 
@@ -1653,7 +1864,8 @@ an array by assigning a larger number to $#array.)  If you say
 
     keys %hash = 200;
 
-then C<%hash> will have at least 200 buckets allocated for it.  These
+then C<%hash> will have at least 200 buckets allocated for it--256 of them, in fact, since 
+it rounds up to the next power of two.  These
 buckets will be retained even if you do C<%hash = ()>, use C<undef
 %hash> if you want to free the storage while C<%hash> is still in scope.
 You can't shrink the number of buckets allocated for the hash using
@@ -1686,9 +1898,12 @@ C<continue> block, if any, is not executed:
 
     LINE: while (<STDIN>) {
 	last LINE if /^$/;	# exit when done with header
-	...
+	#...
     }
 
+See also L</continue> for an illustration of how C<last>, C<next>, and
+C<redo> work.
+
 =item lc EXPR
 
 =item lc
@@ -1713,13 +1928,13 @@ If EXPR is omitted, uses $_.
 
 =item length
 
-Returns the length in characters of the value of EXPR.  If EXPR is
+Returns the length in bytes of the value of EXPR.  If EXPR is
 omitted, returns length of $_.
 
 =item link OLDFILE,NEWFILE
 
-Creates a new filename linked to the old filename.  Returns 1 for
-success, 0 otherwise.
+Creates a new filename linked to the old filename.  Returns TRUE for
+success, FALSE otherwise.
 
 =item listen SOCKET,QUEUESIZE
 
@@ -1728,13 +1943,13 @@ it succeeded, FALSE otherwise.  See example in L<perlipc/"Sockets: Client/Server
 
 =item local EXPR
 
-A local modifies the listed variables to be local to the enclosing block,
-subroutine, C<eval{}>, or C<do>.  If more than one value is listed, the
-list must be placed in parentheses.  See L<perlsub/"Temporary Values via
-local()"> for details, including issues with tied arrays and hashes.
+A local modifies the listed variables to be local to the enclosing
+block, file, or eval.  If more than one value is listed, the list must
+be placed in parentheses.  See L<perlsub/"Temporary Values via local()">
+for details, including issues with tied arrays and hashes.
 
-But you really probably want to be using my() instead, because local() isn't
-what most people think of as "local").  See L<perlsub/"Private Variables
+You really probably want to be using my() instead, because local() isn't
+what most people think of as "local".  See L<perlsub/"Private Variables
 via my()"> for details.
 
 =item localtime EXPR
@@ -1754,18 +1969,28 @@ years since 1900, that is, $year is 123 in year 2023.
 
 If EXPR is omitted, uses the current time (C<localtime(time)>).
 
-In a scalar context, returns the ctime(3) value:
+In scalar context, returns the ctime(3) value:
 
     $now_string = localtime;  # e.g., "Thu Oct 13 04:54:34 1994"
 
-Also see the Time::Local module, and the strftime(3) and mktime(3)
-function available via the POSIX module.
+This scalar value is B<not> locale dependent, see L<perllocale>, but
+instead a Perl builtin.  Also see the Time::Local module, and the
+strftime(3) and mktime(3) function available via the POSIX module.  To
+get somewhat similar but locale dependent date strings, set up your
+locale environment variables appropriately (please see L<perllocale>)
+and try for example:
+
+    use POSIX qw(strftime);
+	$now_string = strftime "%a %b %e %H:%M:%S %Y", localtime;
+
+Note that the C<%a> and C<%b>, the short forms of the day of the week
+and the month of the year, may not necessarily be three characters wide.
 
 =item log EXPR
 
 =item log
 
-Returns logarithm (base I<e>) of EXPR.  If EXPR is omitted, returns log
+Returns the natural logarithm (base I<e>) of EXPR.  If EXPR is omitted, returns log
 of $_.
 
 =item lstat FILEHANDLE
@@ -1774,9 +1999,10 @@ of $_.
 
 =item lstat
 
-Does the same thing as the stat() function, but stats a symbolic link
-instead of the file the symbolic link points to.  If symbolic links are
-unimplemented on your system, a normal stat() is done.
+Does the same thing as the stat() function (including setting the
+special C<_> filehandle) but stats a symbolic link instead of the file
+the symbolic link points to.  If symbolic links are unimplemented on
+your system, a normal stat() is done.
 
 If EXPR is omitted, stats $_.
 
@@ -1806,44 +2032,57 @@ is just a funny way to write
 	$hash{getkey($_)} = $_;
     }
 
+Note that, because $_ is a reference into the list value, it can be used
+to modify the elements of the array.  While this is useful and
+supported, it can cause bizarre results if the LIST is not a named
+array.  See also L</grep> for an array composed of those items of the 
+original list for which the BLOCK or EXPR evaluates to true.
+
 =item mkdir FILENAME,MODE
 
 Creates the directory specified by FILENAME, with permissions specified
-by MODE (as modified by umask).  If it succeeds it returns 1, otherwise
-it returns 0 and sets C<$!> (errno).
+by MODE (as modified by umask).  If it succeeds it returns TRUE, otherwise
+it returns FALSE and sets C<$!> (errno).
 
 =item msgctl ID,CMD,ARG
 
-Calls the System V IPC function msgctl(2).  If CMD is &IPC_STAT, then ARG
-must be a variable which will hold the returned msqid_ds structure.
-Returns like ioctl: the undefined value for error, "0 but true" for
-zero, or the actual return value otherwise.
+Calls the System V IPC function msgctl(2).  You'll probably have to say
+
+    use IPC::SysV;
+
+first to get the correct constant definitions.  If CMD is IPC_STAT,
+then ARG must be a variable which will hold the returned msqid_ds
+structure.  Returns like ioctl: the undefined value for error, "0 but
+true" for zero, or the actual return value otherwise.  See also
+IPC::SysV and IPC::Semaphore::Msg documentation.
 
 =item msgget KEY,FLAGS
 
-Calls the System V IPC function msgget(2).  Returns the message queue id,
-or the undefined value if there is an error.
+Calls the System V IPC function msgget(2).  Returns the message queue
+id, or the undefined value if there is an error.  See also IPC::SysV
+and IPC::SysV::Msg documentation.
 
 =item msgsnd ID,MSG,FLAGS
 
 Calls the System V IPC function msgsnd to send the message MSG to the
 message queue ID.  MSG must begin with the long integer message type,
 which may be created with C<pack("l", $type)>.  Returns TRUE if
-successful, or FALSE if there is an error.
+successful, or FALSE if there is an error.  See also IPC::SysV
+and IPC::SysV::Msg documentation.
 
 =item msgrcv ID,VAR,SIZE,TYPE,FLAGS
 
 Calls the System V IPC function msgrcv to receive a message from
 message queue ID into variable VAR with a maximum message size of
-SIZE.  Note that if a message is received, the message type will be the
-first thing in VAR, and the maximum length of VAR is SIZE plus the size
-of the message type.  Returns TRUE if successful, or FALSE if there is
-an error.
+SIZE.  Note that if a message is received, the message type will be
+the first thing in VAR, and the maximum length of VAR is SIZE plus the
+size of the message type.  Returns TRUE if successful, or FALSE if
+there is an error.  See also IPC::SysV and IPC::SysV::Msg documentation.
 
 =item my EXPR
 
 A "my" declares the listed variables to be local (lexically) to the
-enclosing block, subroutine, C<eval>, or C<do/require/use>'d file.  If
+enclosing block, file, or C<eval>.  If
 more than one value is listed, the list must be placed in parentheses.  See
 L<perlsub/"Private Variables via my()"> for details.
 
@@ -1856,13 +2095,16 @@ the next iteration of the loop:
 
     LINE: while (<STDIN>) {
 	next LINE if /^#/;	# discard comments
-	...
+	#...
     }
 
 Note that if there were a C<continue> block on the above, it would get
 executed even on discarded lines.  If the LABEL is omitted, the command
 refers to the innermost enclosing loop.
 
+See also L</continue> for an illustration of how C<last>, C<next>, and
+C<redo> work.
+
 =item no Module LIST
 
 See the "use" function, which "no" is the opposite of.
@@ -1897,21 +2139,25 @@ to open.)
 
 If the filename begins with '<' or nothing, the file is opened for input.
 If the filename begins with '>', the file is truncated and opened for
-output.  If the filename begins with '>>', the file is opened for
-appending.  You can put a '+' in front of the '>' or '<' to indicate that
+output, being created if necessary. If the filename begins with '>>',
+the file is opened for appending, again being created if necessary. 
+You can put a '+' in front of the '>' or '<' to indicate that
 you want both read and write access to the file; thus '+<' is almost
 always preferred for read/write updates--the '+>' mode would clobber the
-file first.  The prefix and the filename may be separated with spaces.
+file first.  You can't usually use either read-write mode for updating
+textfiles, since they have variable length records.  See the B<-i>
+switch in L<perlrun> for a better approach.
+
+The prefix and the filename may be separated with spaces.
 These various prefixes correspond to the fopen(3) modes of 'r', 'r+', 'w',
 'w+', 'a', and 'a+'.
 
-If the filename begins with "|", the filename is interpreted as a command
-to which output is to be piped, and if the filename ends with a "|", the
-filename is interpreted See L<perlipc/"Using open() for IPC"> for more
-examples of this.  as command which pipes input to us.  (You may not have
-a raw open() to a command that pipes both in I<and> out, but see
-L<IPC::Open2>, L<IPC::Open3>, and L<perlipc/"Bidirectional Communication">
-for alternatives.)
+If the filename begins with "|", the filename is interpreted as a
+command to which output is to be piped, and if the filename ends with a
+"|", the filename is interpreted See L<perlipc/"Using open() for IPC">
+for more examples of this.  (You are not allowed to open() to a command
+that pipes both in I<and> out, but see L<IPC::Open2>, L<IPC::Open3>,
+and L<perlipc/"Bidirectional Communication"> for alternatives.)
 
 Opening '-' opens STDIN and opening 'E<gt>-' opens STDOUT.  Open returns
 nonzero upon success, the undefined value otherwise.  If the open
@@ -1922,10 +2168,18 @@ If you're unfortunate enough to be running Perl on a system that
 distinguishes between text files and binary files (modern operating
 systems don't care), then you should check out L</binmode> for tips for
 dealing with this.  The key distinction between systems that need binmode
-and those that don't is their text file formats.  Systems like Unix and
-Plan9 that delimit lines with a single character, and that encode that
+and those that don't is their text file formats.  Systems like Unix, MacOS, and
+Plan9, which delimit lines with a single character, and which encode that
 character in C as '\n', do not need C<binmode>.  The rest need it.
 
+When opening a file, it's usually a bad idea to continue normal execution
+if the request failed, so C<open> is frequently used in connection with
+C<die>. Even if C<die> won't do what you want (say, in a CGI script,
+where you want to make a nicely formatted error message (but there are
+modules that can help with that problem)) you should always check
+the return value from opening a file. The infrequent exception is when
+working with an unopened filehandle is actually what you want to do.
+
 Examples:
 
     $ARTICLE = 100;
@@ -1933,12 +2187,16 @@ Examples:
     while (<ARTICLE>) {...
 
     open(LOG, '>>/usr/spool/news/twitlog'); # (log is reserved)
+    # if the open fails, output is discarded
 
-    open(DBASE, '+<dbase.mine');	    # open for update
+    open(DBASE, '+<dbase.mine')		    # open for update
+	or die "Can't open 'dbase.mine' for update: $!";
 
-    open(ARTICLE, "caesar <$article |");    # decrypt article
+    open(ARTICLE, "caesar <$article |")     # decrypt article
+	or die "Can't start caesar: $!";
 
-    open(EXTRACT, "|sort >/tmp/Tmp$$");     # $$ is our process id
+    open(EXTRACT, "|sort >/tmp/Tmp$$")      # $$ is our process id
+	or die "Can't start sort: $!";
 
     # process argument list of files along with any includes
 
@@ -1947,25 +2205,26 @@ Examples:
     }
 
     sub process {
-	local($filename, $input) = @_;
+	my($filename, $input) = @_;
 	$input++;		# this is a string increment
 	unless (open($input, $filename)) {
 	    print STDERR "Can't open $filename: $!\n";
 	    return;
 	}
 
+	local $_;
 	while (<$input>) {		# note use of indirection
 	    if (/^#include "(.*)"/) {
 		process($1, $input);
 		next;
 	    }
-	    ...		# whatever
+	    #...		# whatever
 	}
     }
 
 You may also, in the Bourne shell tradition, specify an EXPR beginning
 with "E<gt>&", in which case the rest of the string is interpreted as the
-name of a filehandle (or file descriptor, if numeric) which is to be
+name of a filehandle (or file descriptor, if numeric) to be
 duped and opened.  You may use & after E<gt>, E<gt>E<gt>, E<lt>, +E<gt>,
 +E<gt>E<gt>, and +E<lt>.  The
 mode you specify should match the mode of the original filehandle.
@@ -1975,8 +2234,8 @@ Here is a script that saves, redirects, and restores STDOUT and
 STDERR:
 
     #!/usr/bin/perl
-    open(SAVEOUT, ">&STDOUT");
-    open(SAVEERR, ">&STDERR");
+    open(OLDOUT, ">&STDOUT");
+    open(OLDERR, ">&STDERR");
 
     open(STDOUT, ">foo.out") || die "Can't redirect stdout";
     open(STDERR, ">&STDOUT") || die "Can't dup stdout";
@@ -1990,8 +2249,8 @@ STDERR:
     close(STDOUT);
     close(STDERR);
 
-    open(STDOUT, ">&SAVEOUT");
-    open(STDERR, ">&SAVEERR");
+    open(STDOUT, ">&OLDOUT");
+    open(STDERR, ">&OLDERR");
 
     print STDOUT "stdout 2\n";
     print STDERR "stderr 2\n";
@@ -2024,21 +2283,47 @@ The following pairs are more or less equivalent:
 
 See L<perlipc/"Safe Pipe Opens"> for more examples of this.
 
-NOTE: On any operation which may do a fork, unflushed buffers remain
+NOTE: On any operation that may do a fork, any unflushed buffers remain
 unflushed in both processes, which means you may need to set C<$|> to
 avoid duplicate output.
 
 Closing any piped filehandle causes the parent process to wait for the
 child to finish, and returns the status value in C<$?>.
 
+The filename passed to open will have leading and trailing
+whitespace deleted, and the normal redirection chararacters
+honored.  This property, known as "magic open", 
+can often be used to good effect.  A user could specify a filename of
+"rsh cat file |", or you could change certain filenames as needed:
+
+    $filename =~ s/(.*\.gz)\s*$/gzip -dc < $1|/;
+    open(FH, $filename) or die "Can't open $filename: $!";
+
+However, to open a file with arbitrary weird characters in it, it's
+necessary to protect any leading and trailing whitespace:
+
+    $file =~ s#^(\s)#./$1#;
+    open(FOO, "< $file\0");
+
+If you want a "real" C open() (see L<open(2)> on your system), then you
+should use the sysopen() function, which involves no such magic.  This is
+another way to protect your filenames from interpretation.  For example:
+
+    use IO::Handle;
+    sysopen(HANDLE, $path, O_RDWR|O_CREAT|O_EXCL)
+	or die "sysopen $path: $!";
+    $oldfh = select(HANDLE); $| = 1; select($oldfh);
+    print HANDLE "stuff $$\n");
+    seek(HANDLE, 0, 0);
+    print "File contains: ", <HANDLE>;
+
 Using the constructor from the IO::Handle package (or one of its
-subclasses, such as IO::File or IO::Socket),
-you can generate anonymous filehandles which have the scope of whatever
-variables hold references to them, and automatically close whenever
-and however you leave that scope:
+subclasses, such as IO::File or IO::Socket), you can generate anonymous
+filehandles that have the scope of whatever variables hold references to
+them, and automatically close whenever and however you leave that scope:
 
     use IO::File;
-    ...
+    #...
     sub read_myfile_munged {
 	my $ALL = shift;
 	my $handle = new IO::File;
@@ -2050,26 +2335,6 @@ and however you leave that scope:
 	$first;					# Or here.
     }
 
-The filename that is passed to open will have leading and trailing
-whitespace deleted.  To open a file with arbitrary weird
-characters in it, it's necessary to protect any leading and trailing
-whitespace thusly:
-
-    $file =~ s#^(\s)#./$1#;
-    open(FOO, "< $file\0");
-
-If you want a "real" C open() (see L<open(2)> on your system), then
-you should use the sysopen() function.  This is another way to
-protect your filenames from interpretation.  For example:
-
-    use IO::Handle;
-    sysopen(HANDLE, $path, O_RDWR|O_CREAT|O_EXCL, 0700)
-	or die "sysopen $path: $!";
-    HANDLE->autoflush(1);
-    HANDLE->print("stuff $$\n");
-    seek(HANDLE, 0, 0);
-    print "File contains: ", <HANDLE>;
-
 See L</seek()> for some details about mixing reading and writing.
 
 =item opendir DIRHANDLE,EXPR
@@ -2142,7 +2407,7 @@ follows:
     X	Back up a byte.
     @	Null fill to absolute position.
 
-Each letter may optionally be followed by a number which gives a repeat
+Each letter may optionally be followed by a number giving a repeat
 count.  With all types except "a", "A", "b", "B", "h", "H", and "P" the
 pack function will gobble up that many values from the LIST.  A * for the
 repeat count means to use however many items are left.  The "a" and "A"
@@ -2150,8 +2415,13 @@ types gobble just one value, but pack it as a string of length count,
 padding with nulls or spaces as necessary.  (When unpacking, "A" strips
 trailing spaces and nulls, but "a" does not.)  Likewise, the "b" and "B"
 fields pack a string that many bits long.  The "h" and "H" fields pack a
-string that many nybbles long.  The "P" packs a pointer to a structure of
-the size indicated by the length.  Real numbers (floats and doubles) are
+string that many nybbles long.  The "p" type packs a pointer to a null-
+terminated string.  You are responsible for ensuring the string is not a
+temporary value (which can potentially get deallocated before you get
+around to using the packed result).  The "P" packs a pointer to a structure
+of the size indicated by the length. A NULL pointer is created if the 
+corresponding value for "p" or "P" is C<undef>.
+Real numbers (floats and doubles) are
 in the native machine format only; due to the multiplicity of floating
 formats around, and the lack of a standard "network" representation, no
 facility for interchange has been made.  This means that packed floating
@@ -2194,6 +2464,8 @@ Examples:
 
 The same template may generally also be used in the unpack function.
 
+=item package 
+
 =item package NAMESPACE
 
 Declares the compilation unit as being in the given namespace.  The scope
@@ -2204,12 +2476,16 @@ statement affects only dynamic variables--including those you've used
 local() on--but I<not> lexical variables created with my().  Typically it
 would be the first declaration in a file to be included by the C<require>
 or C<use> operator.  You can switch into a package in more than one place;
-it influences merely which symbol table is used by the compiler for the
+it merely influences which symbol table is used by the compiler for the
 rest of that block.  You can refer to variables and filehandles in other
 packages by prefixing the identifier with the package name and a double
 colon:  C<$Package::Variable>.  If the package name is null, the C<main>
 package as assumed.  That is, C<$::sail> is equivalent to C<$main::sail>.
 
+If NAMESPACE is omitted, then there is no current package, and all
+identifiers must be fully qualified or lexicals.  This is stricter
+than C<use strict>, since it also extends to function names.
+
 See L<perlmod/"Packages"> for more information about packages, modules,
 and classes.  See L<perlsub> for other scoping issues.
 
@@ -2262,11 +2538,11 @@ token is a term, it may be misinterpreted as an operator unless you
 interpose a + or put parentheses around the arguments.)  If FILEHANDLE is
 omitted, prints by default to standard output (or to the last selected
 output channel--see L</select>).  If LIST is also omitted, prints $_ to
-STDOUT.  To set the default output channel to something other than
+the currently selected output channel.  To set the default output channel to something other than
 STDOUT use the select operation.  Note that, because print takes a
-LIST, anything in the LIST is evaluated in a list context, and any
+LIST, anything in the LIST is evaluated in list context, and any
 subroutine that you call will have one or more of its expressions
-evaluated in a list context.  Also be careful not to follow the print
+evaluated in list context.  Also be careful not to follow the print
 keyword with a left parenthesis unless you want the corresponding right
 parenthesis to terminate the arguments to the print--interpose a + or
 put parentheses around all the arguments.
@@ -2281,13 +2557,14 @@ you will have to use a block returning its value instead:
 
 =item printf FORMAT, LIST
 
-Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>.  The first argument
+Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>, except that $\
+(the output record separator) is not appended.  The first argument
 of the list will be interpreted as the printf format.  If C<use locale> is
 in effect, the character used for the decimal point in formatted real numbers
 is affected by the LC_NUMERIC locale.  See L<perllocale>.
 
 Don't fall into the trap of using a printf() when a simple
-print() would do.  The print() is more efficient, and less
+print() would do.  The print() is more efficient and less
 error prone.
 
 =item prototype FUNCTION
@@ -2296,6 +2573,13 @@ Returns the prototype of a function as a string (or C<undef> if the
 function has no prototype).  FUNCTION is a reference to, or the name of,
 the function whose prototype you want to retrieve.
 
+If FUNCTION is a string starting with C<CORE::>, the rest is taken as
+a name for Perl builtin.  If builtin is not I<overridable> (such as
+C<qw>) or its arguments cannot be expressed by a prototype (such as
+C<system>) - in other words, the builtin does not behave like a Perl
+function - returns C<undef>.  Otherwise, the string describing the
+equivalent prototype is returned.
+
 =item push ARRAY,LIST
 
 Treats ARRAY as a stack, and pushes the values of LIST
@@ -2349,19 +2633,19 @@ with the wrong number of RANDBITS.)
 =item read FILEHANDLE,SCALAR,LENGTH
 
 Attempts to read LENGTH bytes of data into variable SCALAR from the
-specified FILEHANDLE.  Returns the number of bytes actually read, or
-undef if there was an error.  SCALAR will be grown or shrunk to the
-length actually read.  An OFFSET may be specified to place the read
-data at some other place than the beginning of the string.  This call
-is actually implemented in terms of stdio's fread call.  To get a true
-read system call, see sysread().
+specified FILEHANDLE.  Returns the number of bytes actually read,
+C<0> at end of file, or undef if there was an error.  SCALAR will be grown
+or shrunk to the length actually read.  An OFFSET may be specified to
+place the read data at some other place than the beginning of the
+string.  This call is actually implemented in terms of stdio's fread(3)
+call.  To get a true read(2) system call, see sysread().
 
 =item readdir DIRHANDLE
 
 Returns the next directory entry for a directory opened by opendir().
-If used in a list context, returns all the rest of the entries in the
+If used in list context, returns all the rest of the entries in the
 directory.  If there are no more entries, returns an undefined value in
-a scalar context or a null list in a list context.
+scalar context or a null list in list context.
 
 If you're planning to filetest the return values out of a readdir(), you'd
 better prepend the directory in question.  Otherwise, because we didn't
@@ -2371,6 +2655,19 @@ chdir() there, it would have been testing the wrong file.
     @dots = grep { /^\./ && -f "$some_dir/$_" } readdir(DIR);
     closedir DIR;
 
+=item readline EXPR
+
+Reads from the filehandle whose typeglob is contained in EXPR.  In scalar context, a single line
+is read and returned.  In list context, reads until end-of-file is
+reached and returns a list of lines (however you've defined lines
+with $/ or $INPUT_RECORD_SEPARATOR).
+This is the internal function implementing the C<E<lt>EXPRE<gt>>
+operator, but you can use it directly.  The C<E<lt>EXPRE<gt>>
+operator is discussed in more detail in L<perlop/"I/O Operators">.
+
+    $line = <STDIN>;
+    $line = readline(*STDIN);		# same thing
+
 =item readlink EXPR
 
 =item readlink
@@ -2380,11 +2677,22 @@ implemented.  If not, gives a fatal error.  If there is some system
 error, returns the undefined value and sets C<$!> (errno).  If EXPR is
 omitted, uses $_.
 
+=item readpipe EXPR
+
+EXPR is executed as a system command.
+The collected standard output of the command is returned.
+In scalar context, it comes back as a single (potentially
+multi-line) string.  In list context, returns a list of lines
+(however you've defined lines with $/ or $INPUT_RECORD_SEPARATOR).
+This is the internal function implementing the C<qx/EXPR/>
+operator, but you can use it directly.  The C<qx/EXPR/>
+operator is discussed in more detail in L<perlop/"I/O Operators">.
+
 =item recv SOCKET,SCALAR,LEN,FLAGS
 
 Receives a message on a socket.  Attempts to receive LENGTH bytes of
 data into variable SCALAR from the specified SOCKET filehandle.
-Actually does a C recvfrom(), so that it can returns the address of the
+Actually does a C recvfrom(), so that it can return the address of the
 sender.  Returns the undefined value if there's an error.  SCALAR will
 be grown or shrunk to the length actually read.  Takes the same flags
 as the system call of the same name.
@@ -2409,7 +2717,7 @@ themselves about what was just input:
 	    $front = $_;
 	    while (<STDIN>) {
 		if (/}/) {	# end of comment?
-		    s|^|$front{|;
+		    s|^|$front\{|;
 		    redo LINE;
 		}
 	    }
@@ -2417,6 +2725,9 @@ themselves about what was just input:
 	print;
     }
 
+See also L</continue> for an illustration of how C<last>, C<next>, and
+C<redo> work.
+
 =item ref EXPR
 
 =item ref
@@ -2439,7 +2750,7 @@ name is returned instead.  You can think of ref() as a typeof() operator.
     if (ref($r) eq "HASH") {
 	print "r is a reference to a hash.\n";
     }
-    if (!ref ($r) {
+    if (!ref($r)) {
 	print "r is not a reference at all.\n";
     }
 
@@ -2464,9 +2775,9 @@ essentially just a variety of eval().  Has semantics similar to the following
 subroutine:
 
     sub require {
-	local($filename) = @_;
+	my($filename) = @_;
 	return 1 if $INC{$filename};
-	local($realfilename,$result);
+	my($realfilename,$result);
 	ITER: {
 	    foreach $prefix (@INC) {
 		$realfilename = "$prefix/$filename";
@@ -2480,7 +2791,7 @@ subroutine:
 	die $@ if $@;
 	die "$filename did not return true value" unless $result;
 	$INC{$filename} = $realfilename;
-	$result;
+	return $result;
     }
 
 Note that the file will not be included twice under the same specified
@@ -2495,8 +2806,26 @@ replaces "F<::>" with "F</>" in the filename for you,
 to make it easy to load standard modules.  This form of loading of
 modules does not risk altering your namespace.
 
-For a yet-more-powerful import facility, see L</use> and
-L<perlmod>.
+In other words, if you try this:
+
+        require Foo::Bar; 	# a splendid bareword 
+
+The require function will actually look for the "Foo/Bar.pm" file in the 
+directories specified in the @INC array.
+
+But if you try this:
+
+        $class = 'Foo::Bar';
+        require $class; 	# $class is not a bareword
+    #or
+        require "Foo::Bar"; # not a bareword because of the ""
+
+The require function will look for the "Foo::Bar" file in the @INC array and 
+will complain about not finding "Foo::Bar" there. In this case you can do:
+
+        eval "require $class";
+
+For a yet-more-powerful import facility, see L</use> and L<perlmod>.
 
 =item reset EXPR
 
@@ -2524,20 +2853,20 @@ so you'll probably want to use them instead.  See L</my>.
 
 =item return
 
-Returns from a subroutine, eval(), or do FILE with the value of the
-given EXPR.  Evaluation of EXPR may be in a list, scalar, or void
+Returns from a subroutine, eval(), or C<do FILE> with the value 
+given in EXPR.  Evaluation of EXPR may be in list, scalar, or void
 context, depending on how the return value will be used, and the context
 may vary from one execution to the next (see wantarray()).  If no EXPR
-is given, returns an empty list in a list context, an undefined value in
-a scalar context, or nothing in a void context.
+is given, returns an empty list in list context, an undefined value in
+scalar context, or nothing in a void context.
 
 (Note that in the absence of a return, a subroutine, eval, or do FILE
 will automatically return the value of the last expression evaluated.)
 
 =item reverse LIST
 
-In a list context, returns a list value consisting of the elements
-of LIST in the opposite order.  In a scalar context, concatenates the
+In list context, returns a list value consisting of the elements
+of LIST in the opposite order.  In scalar context, concatenates the
 elements of LIST, and returns a string value consisting of those bytes,
 but in the opposite order.
 
@@ -2571,8 +2900,8 @@ last occurrence at or before that position.
 
 =item rmdir
 
-Deletes the directory specified by FILENAME if it is empty.  If it
-succeeds it returns 1, otherwise it returns 0 and sets C<$!> (errno).  If
+Deletes the directory specified by FILENAME if that directory is empty.  If it
+succeeds it returns TRUE, otherwise it returns FALSE and sets C<$!> (errno).  If
 FILENAME is omitted, uses $_.
 
 =item s///
@@ -2581,13 +2910,13 @@ The substitution operator.  See L<perlop>.
 
 =item scalar EXPR
 
-Forces EXPR to be interpreted in a scalar context and returns the value
+Forces EXPR to be interpreted in scalar context and returns the value
 of EXPR.
 
     @counts = ( scalar @a, scalar @b, scalar @c );
 
 There is no equivalent operator to force an expression to
-be interpolated in a list context because it's in practice never
+be interpolated in list context because it's in practice never
 needed.  If you really wanted to do so, however, you could use
 the construction C<@{[ (some expression) ]}>, but usually a simple
 C<(some expression)> suffices.
@@ -2679,8 +3008,8 @@ If you want to select on many filehandles you might wish to write a
 subroutine:
 
     sub fhbits {
-	local(@fhlist) = split(' ',$_[0]);
-	local($bits);
+	my(@fhlist) = split(' ',$_[0]);
+	my($bits);
 	for (@fhlist) {
 	    vec($bits,fileno($_),1) = 1;
 	}
@@ -2698,7 +3027,7 @@ or to block until something becomes ready just do this
     $nfound = select($rout=$rin, $wout=$win, $eout=$ein, undef);
 
 Most systems do not bother to return anything useful in $timeleft, so
-calling select() in a scalar context just returns $nfound.
+calling select() in scalar context just returns $nfound.
 
 Any of the bit masks can also be undef.  The timeout, if specified, is
 in seconds, which may be fractional.  Note: not all implementations are
@@ -2709,21 +3038,27 @@ You can effect a sleep of 250 milliseconds this way:
 
     select(undef, undef, undef, 0.25);
 
-B<WARNING>: Do not attempt to mix buffered I/O (like read() or E<lt>FHE<gt>)
-with select().  You have to use sysread() instead.
+B<WARNING>: One should not attempt to mix buffered I/O (like read()
+or E<lt>FHE<gt>) with select(), except as permitted by POSIX, and even
+then only on POSIX systems.  You have to use sysread() instead.
 
 =item semctl ID,SEMNUM,CMD,ARG
 
-Calls the System V IPC function semctl.  If CMD is &IPC_STAT or
-&GETALL, then ARG must be a variable which will hold the returned
+Calls the System V IPC function semctl.  You'll probably have to say
+
+    use IPC::SysV;
+
+first to get the correct constant definitions.  If CMD is IPC_STAT or
+GETALL, then ARG must be a variable which will hold the returned
 semid_ds structure or semaphore value array.  Returns like ioctl: the
 undefined value for error, "0 but true" for zero, or the actual return
-value otherwise.
+value otherwise.  See also IPC::SysV and IPC::Semaphore documentation.
 
 =item semget KEY,NSEMS,FLAGS
 
 Calls the System V IPC function semget.  Returns the semaphore id, or
-the undefined value if there is an error.
+the undefined value if there is an error.  See also IPC::SysV and
+IPC::SysV::Semaphore documentation.
 
 =item semop KEY,OPSTRING
 
@@ -2738,7 +3073,8 @@ following code waits on semaphore $semnum of semaphore id $semid:
     $semop = pack("sss", $semnum, -1, 0);
     die "Semaphore trouble: $!\n" unless semop($semid, $semop);
 
-To signal the semaphore, replace "-1" with "1".
+To signal the semaphore, replace "-1" with "1".  See also IPC::SysV
+and IPC::SysV::Semaphore documentation.
 
 =item send SOCKET,MSG,FLAGS,TO
 
@@ -2778,22 +3114,30 @@ argument.
 Shifts the first value of the array off and returns it, shortening the
 array by 1 and moving everything down.  If there are no elements in the
 array, returns the undefined value.  If ARRAY is omitted, shifts the
-@ARGV array in the main program, and the @_ array in subroutines.
-(This is determined lexically.)  See also unshift(), push(), and pop().
-Shift() and unshift() do the same thing to the left end of an array
-that pop() and push() do to the right end.
+@_ array within the lexical scope of subroutines and formats, and the
+@ARGV array at file scopes or within the lexical scopes established by
+the C<eval ''>, C<BEGIN {}>, C<END {}>, and C<INIT {}> constructs.
+See also unshift(), push(), and pop().  Shift() and unshift() do the
+same thing to the left end of an array that pop() and push() do to the
+right end.
 
 =item shmctl ID,CMD,ARG
 
-Calls the System V IPC function shmctl.  If CMD is &IPC_STAT, then ARG
-must be a variable which will hold the returned shmid_ds structure.
-Returns like ioctl: the undefined value for error, "0 but true" for
-zero, or the actual return value otherwise.
+Calls the System V IPC function shmctl.  You'll probably have to say
+
+    use IPC::SysV;
+
+first to get the correct constant definitions.  If CMD is IPC_STAT,
+then ARG must be a variable which will hold the returned shmid_ds
+structure.  Returns like ioctl: the undefined value for error, "0 but
+true" for zero, or the actual return value otherwise.
+See also IPC::SysV documentation.
 
 =item shmget KEY,SIZE,FLAGS
 
 Calls the System V IPC function shmget.  Returns the shared memory
 segment id, or the undefined value if there is an error.
+See also IPC::SysV documentation.
 
 =item shmread ID,VAR,POS,SIZE
 
@@ -2801,16 +3145,27 @@ segment id, or the undefined value if there is an error.
 
 Reads or writes the System V shared memory segment ID starting at
 position POS for size SIZE by attaching to it, copying in/out, and
-detaching from it.  When reading, VAR must be a variable which will
+detaching from it.  When reading, VAR must be a variable that will
 hold the data read.  When writing, if STRING is too long, only SIZE
 bytes are used; if STRING is too short, nulls are written to fill out
 SIZE bytes.  Return TRUE if successful, or FALSE if there is an error.
+See also IPC::SysV documentation.
 
 =item shutdown SOCKET,HOW
 
 Shuts down a socket connection in the manner indicated by HOW, which
 has the same interpretation as in the system call of the same name.
 
+    shutdown(SOCKET, 0);                # I/we have stopped reading data
+    shutdown(SOCKET, 1);                # I/we have stopped writing data
+    shutdown(SOCKET, 2);                # I/we have stopped using this socket
+
+This is useful with sockets when you want to tell the other
+side you're done writing but not done reading, or vice versa.
+It's also a more insistent form of close because it also 
+disables the filedescriptor in any forked copies in other
+processes.
+
 =item sin EXPR
 
 =item sin
@@ -2828,17 +3183,20 @@ function, or use this relation:
 =item sleep
 
 Causes the script to sleep for EXPR seconds, or forever if no EXPR.
-May be interrupted by sending the process a SIGALRM.  Returns the
-number of seconds actually slept.  You probably cannot mix alarm() and
-sleep() calls, because sleep() is often implemented using alarm().
+May be interrupted if the process receives a signal such as SIGALRM.
+Returns the number of seconds actually slept.  You probably cannot
+mix alarm() and sleep() calls, because sleep() is often implemented
+using alarm().
 
 On some older systems, it may sleep up to a full second less than what
 you requested, depending on how it counts seconds.  Most modern systems
-always sleep the full amount.
+always sleep the full amount.  They may appear to sleep longer than that,
+however, because your process might not be scheduled right away in a
+busy multitasking system.
 
 For delays of finer granularity than one second, you may use Perl's
 syscall() interface to access setitimer(2) if your system supports it,
-or else see L</select()> below.
+or else see L</select()> above.
 
 See also the POSIX module's sigpause() function.
 
@@ -2856,6 +3214,16 @@ specified type.  DOMAIN, TYPE, and PROTOCOL are specified the same as
 for the system call of the same name.  If unimplemented, yields a fatal
 error.  Returns TRUE if successful.
 
+Some systems defined pipe() in terms of socketpair, in which a call
+to C<pipe(Rdr, Wtr)> is essentially:
+
+    use Socket;
+    socketpair(Rdr, Wtr, AF_UNIX, SOCK_STREAM, PF_UNSPEC);
+    shutdown(Rdr, 1);        # no more writing for reader
+    shutdown(Wtr, 0);        # no more reading for writer
+
+See L<perlipc> for an example of socketpair use.
+
 =item sort SUBNAME LIST
 
 =item sort BLOCK LIST
@@ -2868,9 +3236,10 @@ specified, it gives the name of a subroutine that returns an integer
 less than, equal to, or greater than 0, depending on how the elements
 of the array are to be ordered.  (The C<E<lt>=E<gt>> and C<cmp>
 operators are extremely useful in such routines.)  SUBNAME may be a
-scalar variable name, in which case the value provides the name of the
-subroutine to use.  In place of a SUBNAME, you can provide a BLOCK as
-an anonymous, in-line sort subroutine.
+scalar variable name (unsubscripted), in which case the value provides
+the name of (or a reference to) the actual subroutine to use.  In place
+of a SUBNAME, you can provide a BLOCK as an anonymous, in-line sort
+subroutine.
 
 In the interests of efficiency the normal calling code for subroutines is
 bypassed, with the following effects: the subroutine may not be a
@@ -2986,22 +3355,26 @@ sanity checks in the interest of speed.
 =item splice ARRAY,OFFSET
 
 Removes the elements designated by OFFSET and LENGTH from an array, and
-replaces them with the elements of LIST, if any.  Returns the elements
-removed from the array.  The array grows or shrinks as necessary.  If
-LENGTH is omitted, removes everything from OFFSET onward.  The
-following equivalences hold (assuming C<$[ == 0>):
-
-    push(@a,$x,$y)	splice(@a,$#a+1,0,$x,$y)
+replaces them with the elements of LIST, if any.  In list context,
+returns the elements removed from the array.  In scalar context,
+returns the last element removed, or C<undef> if no elements are
+removed.  The array grows or shrinks as necessary.
+If OFFSET is negative then it start that far from the end of the array.
+If LENGTH is omitted, removes everything from OFFSET onward.
+If LENGTH is negative, leave that many elements off the end of the array.
+The following equivalences hold (assuming C<$[ == 0>):
+
+    push(@a,$x,$y)	splice(@a,@a,0,$x,$y)
     pop(@a)		splice(@a,-1)
     shift(@a)		splice(@a,0,1)
     unshift(@a,$x,$y)	splice(@a,0,0,$x,$y)
-    $a[$x] = $y		splice(@a,$x,1,$y);
+    $a[$x] = $y		splice(@a,$x,1,$y)
 
 Example, assuming array lengths are passed before arrays:
 
     sub aeq {	# compare two list values
-	local(@a) = splice(@_,0,shift);
-	local(@b) = splice(@_,0,shift);
+	my(@a) = splice(@_,0,shift);
+	my(@b) = splice(@_,0,shift);
 	return 0 unless @a == @b;	# same len?
 	while (@a) {
 	    return 0 if pop(@a) ne pop(@b);
@@ -3018,22 +3391,25 @@ Example, assuming array lengths are passed before arrays:
 
 =item split
 
-Splits a string into an array of strings, and returns it.
+Splits a string into an array of strings, and returns it.  By default,
+empty leading fields are preserved, and empty trailing ones are deleted.
 
-If not in a list context, returns the number of fields found and splits into
-the @_ array.  (In a list context, you can force the split into @_ by
-using C<??> as the pattern delimiters, but it still returns the array
-value.)  The use of implicit split to @_ is deprecated, however.
+If not in list context, returns the number of fields found and splits into
+the @_ array.  (In list context, you can force the split into @_ by
+using C<??> as the pattern delimiters, but it still returns the list
+value.)  The use of implicit split to @_ is deprecated, however, because
+it clobbers your subroutine arguments.
 
 If EXPR is omitted, splits the $_ string.  If PATTERN is also omitted,
 splits on whitespace (after skipping any leading whitespace).  Anything
 matching PATTERN is taken to be a delimiter separating the fields.  (Note
-that the delimiter may be longer than one character.)  If LIMIT is
-specified and is not negative, splits into no more than that many fields
-(though it may split into fewer).  If LIMIT is unspecified, trailing null
-fields are stripped (which potential users of pop() would do well to
-remember).  If LIMIT is negative, it is treated as if an arbitrarily large
-LIMIT had been specified.
+that the delimiter may be longer than one character.)
+
+If LIMIT is specified and positive, splits into no more than that
+many fields (though it may split into fewer).  If LIMIT is unspecified
+or zero, trailing null fields are stripped (which potential users
+of pop() would do well to remember).  If LIMIT is negative, it is
+treated as if an arbitrarily large LIMIT had been specified.
 
 A pattern matching the null string (not to be confused with
 a null pattern C<//>, which is just one member of the set of patterns
@@ -3067,7 +3443,7 @@ If you had the entire header of a normal Unix email message in $header,
 you could split it up into fields and their values this way:
 
     $header =~ s/\n\s+/ /g;  # fix continuation lines
-    %hdrs   =  (UNIX_FROM => split /^(.*?):\s*/m, $header);
+    %hdrs   =  (UNIX_FROM => split /^(\S*?):\s*/m, $header);
 
 The pattern C</PATTERN/> may be replaced with an expression to specify
 patterns that vary at runtime.  (To do runtime compilation only once,
@@ -3083,11 +3459,10 @@ really does a C<split(' ', $_)> internally.
 
 Example:
 
-    open(passwd, '/etc/passwd');
-    while (<passwd>) {
-	($login, $passwd, $uid, $gid, $gcos,
-	    $home, $shell) = split(/:/);
-	...
+    open(PASSWD, '/etc/passwd');
+    while (<PASSWD>) {
+	($login, $passwd, $uid, $gid, $gcos,$home, $shell) = split(/:/);
+	#...
     }
 
 (Note that $shell above will still have a newline on it.  See L</chop>,
@@ -3099,7 +3474,7 @@ Returns a string formatted by the usual printf conventions of the
 C library function sprintf().  See L<sprintf(3)> or L<printf(3)>
 on your system for an explanation of the general principles.
 
-Perl does all of its own sprintf() formatting -- it emulates the C
+Perl does its own sprintf() formatting -- it emulates the C
 function sprintf(), but it doesn't use it (except for floating-point
 numbers, and even then only the standard modifiers are allowed).  As a
 result, any non-standard extensions in your local sprintf() are not
@@ -3143,7 +3518,7 @@ and the conversion letter:
    +       prefix positive number with a plus sign
    -       left-justify within the field
    0       use zeros, not spaces, to right-justify
-   #       prefix octal with "0", hex with "0x"
+   #       prefix non-zero octal with "0", non-zero hex with "0x"
    number  minimum field width
    .number "precision": digits after decimal point for floating-point,
            max length for string, minimum length for integer
@@ -3180,7 +3555,7 @@ omitted, uses a semi-random value based on the current time and process
 ID, among other things.  In versions of Perl prior to 5.004 the default
 seed was just the current time().  This isn't a particularly good seed,
 so many old programs supply their own seed value (often C<time ^ $$> or
-C<time ^ ($$ + ($$ << 15))>), but that isn't necessary any more.
+C<time ^ ($$ + ($$ E<lt>E<lt> 15))>), but that isn't necessary any more.
 
 In fact, it's usually not necessary to call srand() at all, because if
 it is not called explicitly, it is called implicitly at the first use of
@@ -3220,11 +3595,10 @@ one-third of the time.  So don't do that.
 
 =item stat
 
-Returns a 13-element array giving the status info for a file, either the
-file opened via FILEHANDLE, or named by EXPR.  If EXPR is omitted, it
-stats $_.  Returns a null list if the stat fails.  Typically used as
-follows:
-
+Returns a 13-element list giving the status info for a file, either
+the file opened via FILEHANDLE, or named by EXPR.  If EXPR is omitted,
+it stats $_.  Returns a null list if the stat fails.  Typically used
+as follows:
 
     ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
        $atime,$mtime,$ctime,$blksize,$blocks)
@@ -3259,6 +3633,10 @@ last stat or filetest are returned.  Example:
 
 (This works on machines only for which the device number is negative under NFS.)
 
+In scalar context, C<stat> returns a boolean value indicating success
+or failure, and, if successful, sets the information associated with
+the special filehandle C<_>.
+
 =item study SCALAR
 
 =item study
@@ -3279,7 +3657,7 @@ the rarest character is selected, based on some static frequency tables
 constructed from some C programs and English text.  Only those places
 that contain this "rarest" character are examined.)
 
-For example, here is a loop which inserts index producing entries
+For example, here is a loop that inserts index producing entries
 before any line containing a certain pattern:
 
     while (<>) {
@@ -3287,11 +3665,11 @@ before any line containing a certain pattern:
 	print ".IX foo\n" if /\bfoo\b/;
 	print ".IX bar\n" if /\bbar\b/;
 	print ".IX blurfl\n" if /\bblurfl\b/;
-	...
+	# ...
 	print;
     }
 
-In searching for /\bfoo\b/, only those locations in $_ that contain "f"
+In searching for C</\bfoo\b/>, only those locations in $_ that contain "f"
 will be looked at, because "f" is rarer than "o".  In general, this is
 a big win except in pathological cases.  The only question is whether
 it saves you more time than it took to build the linked list in the
@@ -3330,17 +3708,23 @@ a NAME, it's an anonymous function declaration, and does actually return a
 value: the CODE ref of the closure you just created.  See L<perlsub> and
 L<perlref> for details.
 
+=item substr EXPR,OFFSET,LEN,REPLACEMENT
+
 =item substr EXPR,OFFSET,LEN
 
 =item substr EXPR,OFFSET
 
 Extracts a substring out of EXPR and returns it.  First character is at
 offset 0, or whatever you've set C<$[> to (but don't do that).
-If OFFSET is negative, starts
+If OFFSET is negative (or more precisely, less than C<$[>), starts
 that far from the end of the string.  If LEN is omitted, returns
 everything to the end of the string.  If LEN is negative, leaves that
 many characters off the end of the string.
 
+If you specify a substring that is partly outside the string, the part
+within the string is returned.    If the substring is totally outside
+the string a warning is produced.
+
 You can use the substr() function
 as an lvalue, in which case EXPR must be an lvalue.  If you assign
 something shorter than LEN, the string will shrink, and if you assign
@@ -3348,6 +3732,10 @@ something longer than LEN, the string will grow to accommodate it.  To
 keep the string the same length you may need to pad or chop your value
 using sprintf().
 
+An alternative to using substr() as an lvalue is to specify the
+replacement string as the 4th argument.  This allows you to replace
+parts of the EXPR and return what was there before in one operation.
+
 =item symlink OLDFILE,NEWFILE
 
 Creates a new filename symbolically linked to the old filename.
@@ -3355,7 +3743,7 @@ Returns 1 for success, 0 otherwise.  On systems that don't support
 symbolic links, produces a fatal error at run time.  To check for that,
 use eval:
 
-    $symlink_exists = (eval {symlink("","")};, $@ eq '');
+    $symlink_exists =  eval { symlink("",""); 1 };
 
 =item syscall LIST
 
@@ -3365,17 +3753,32 @@ unimplemented, produces a fatal error.  The arguments are interpreted
 as follows: if a given argument is numeric, the argument is passed as
 an int.  If not, the pointer to the string value is passed.  You are
 responsible to make sure a string is pre-extended long enough to
-receive any result that might be written into a string.  If your
+receive any result that might be written into a string.  You can't use a
+string literal (or other read-only string) as an argument to syscall()
+because Perl has to assume that any string pointer might be written
+through.  If your
 integer arguments are not literals and have never been interpreted in a
 numeric context, you may need to add 0 to them to force them to look
-like numbers.
+like numbers.  This emulates the syswrite() function (or vice versa):
 
     require 'syscall.ph';		# may need to run h2ph
-    syscall(&SYS_write, fileno(STDOUT), "hi there\n", 9);
+    $s = "hi there\n";
+    syscall(&SYS_write, fileno(STDOUT), $s, length $s);
 
 Note that Perl supports passing of up to only 14 arguments to your system call,
 which in practice should usually suffice.
 
+Syscall returns whatever value returned by the system call it calls.
+If the system call fails, syscall returns -1 and sets C<$!> (errno).
+Note that some system calls can legitimately return -1.  The proper
+way to handle such calls is to assign C<$!=0;> before the call and
+check the value of C<$!> if syscall returns -1.
+
+There's a problem with C<syscall(&SYS_pipe)>: it returns the file
+number of the read end of the pipe it creates.  There is no way
+to retrieve the file number of the other end.  You can avoid this 
+problem by using C<pipe> instead.
+
 =item sysopen FILEHANDLE,FILENAME,MODE
 
 =item sysopen FILEHANDLE,FILENAME,MODE,PERMS
@@ -3391,11 +3794,26 @@ system-dependent; they are available via the standard module C<Fcntl>.
 However, for historical reasons, some values are universal: zero means
 read-only, one means write-only, and two means read/write.
 
-If the file named by FILENAME does not exist and the C<open> call
-creates it (typically because MODE includes the O_CREAT flag), then
-the value of PERMS specifies the permissions of the newly created
-file.  If PERMS is omitted, the default value is 0666, which allows
-read and write for all.  This default is reasonable: see C<umask>.
+If the file named by FILENAME does not exist and the C<open> call creates
+it (typically because MODE includes the O_CREAT flag), then the value of
+PERMS specifies the permissions of the newly created file.  If you omit
+the PERMS argument to C<sysopen>, Perl uses the octal value C<0666>.
+These permission values need to be in octal, and are modified by your
+process's current C<umask>.  The C<umask> value is a number representing
+disabled permissions bits--if your C<umask> were 027 (group can't write;
+others can't read, write, or execute), then passing C<sysopen> 0666 would
+create a file with mode 0640 (C<0666 &~ 027> is 0640).
+
+If you find this C<umask> talk confusing, here's some advice: supply a
+creation mode of 0666 for regular files and one of 0777 for directories
+(in C<mkdir>) and executable files.  This gives users the freedom of
+choice: if they want protected files, they might choose process umasks
+of 022, 027, or even the particularly antisocial mask of 077.  Programs
+should rarely if ever make policy decisions better left to the user.
+The exception to this is when writing files that should be kept private:
+mail files, web browser cookies, I<.rhosts> files, and so on.  In short,
+seldom if ever use 0644 as argument to C<sysopen> because that takes
+away the user's option to have a more permissive umask.  Better to omit it.
 
 The IO::File module provides a more object-oriented approach, if you're
 into that kind of thing.
@@ -3405,12 +3823,12 @@ into that kind of thing.
 =item sysread FILEHANDLE,SCALAR,LENGTH
 
 Attempts to read LENGTH bytes of data into variable SCALAR from the
-specified FILEHANDLE, using the system call read(2).  It bypasses stdio,
-so mixing this with other kinds of reads, print(), write(), seek(), or
-tell() can cause confusion.  Returns the number of bytes actually read,
+specified FILEHANDLE, using the system call read(2).  It bypasses
+stdio, so mixing this with other kinds of reads, print(), write(),
+seek(), or tell() can cause confusion because stdio usually buffers
+data.  Returns the number of bytes actually read, C<0> at end of file,
 or undef if there was an error.  SCALAR will be grown or shrunk so that
-the last byte actually read is the last byte of the scalar after the
-read.
+the last byte actually read is the last byte of the scalar after the read.
 
 An OFFSET may be specified to place the read data at some place in the
 string other than the beginning.  A negative OFFSET specifies
@@ -3438,15 +3856,30 @@ the new position.
 
 =item system LIST
 
+=item system PROGRAM LIST
+
 Does exactly the same thing as "exec LIST" except that a fork is done
 first, and the parent process waits for the child process to complete.
 Note that argument processing varies depending on the number of
-arguments.  The return value is the exit status of the program as
+arguments.  If there is more than one argument in LIST, or if LIST is
+an array with more than one value, starts the program given by the
+first element of the list with arguments given by the rest of the list.
+If there is only one scalar argument, the argument is
+checked for shell metacharacters, and if there are any, the entire
+argument is passed to the system's command shell for parsing (this is
+C</bin/sh -c> on Unix platforms, but varies on other platforms).  If
+there are no shell metacharacters in the argument, it is split into
+words and passed directly to execvp(), which is more efficient.
+
+The return value is the exit status of the program as
 returned by the wait() call.  To get the actual exit value divide by
 256.  See also L</exec>.  This is I<NOT> what you want to use to capture
 the output from a command, for that you should use merely backticks or
 qx//, as described in L<perlop/"`STRING`">.
 
+Like exec(), system() allows you to lie to a program about its name if
+you use the "system PROGRAM LIST" syntax.  Again, see L</exec>.
+
 Because system() and backticks block SIGINT and SIGQUIT, killing the
 program they're running doesn't actually interrupt your program.
 
@@ -3454,31 +3887,16 @@ program they're running doesn't actually interrupt your program.
     system(@args) == 0
 	 or die "system @args failed: $?"
 
-Here's a more elaborate example of analysing the return value from
-system() on a Unix system to check for all possibilities, including for
-signals and core dumps.
+You can check all the failure possibilities by inspecting
+C<$?> like this:
 
-    $rc = 0xffff & system @args;
-    printf "system(%s) returned %#04x: ", "@args", $rc;
-    if ($rc == 0) {
-	print "ran with normal exit\n";
-    }
-    elsif ($rc == 0xff00) {
-	print "command failed: $!\n";
-    }
-    elsif ($rc > 0x80) {
-	$rc >>= 8;
-	print "ran with non-zero exit status $rc\n";
-    }
-    else {
-	print "ran with ";
-	if ($rc &   0x80) {
-	    $rc &= ~0x80;
-	    print "core dump from ";
-	}
-	print "signal $rc\n"
-    }
-    $ok = ($rc != 0);
+    $exit_value  = $? >> 8;
+    $signal_num  = $? & 127;
+    $dumped_core = $? & 128;
+
+When the arguments get executed via the system shell, results
+and return codes will be subject to its quirks and capabilities.
+See L<perlop/"`STRING`"> and L</exec> for details.
 
 =item syswrite FILEHANDLE,SCALAR,LENGTH,OFFSET
 
@@ -3487,14 +3905,16 @@ signals and core dumps.
 Attempts to write LENGTH bytes of data from variable SCALAR to the
 specified FILEHANDLE, using the system call write(2).  It bypasses
 stdio, so mixing this with reads (other than sysread()), print(),
-write(), seek(), or tell() may cause confusion.  Returns the number of
-bytes actually written, or undef if there was an error.  If the length
-is greater than the available data, only as much data as is available
+write(), seek(), or tell() may cause confusion because stdio usually
+buffers data.  Returns the number of bytes actually written, or undef
+if there was an error.  If the LENGTH is greater than the available
+data in the SCALAR after the OFFSET, only as much data as is available
 will be written.
 
 An OFFSET may be specified to write the data from some part of the
 string other than the beginning.  A negative OFFSET specifies writing
-that many bytes counting backwards from the end of the string.
+that many bytes counting backwards from the end of the string.  In the
+case the SCALAR is empty you can use OFFSET but only zero offset.
 
 =item tell FILEHANDLE
 
@@ -3523,9 +3943,9 @@ function of C.  The object returned by the "new" method is also
 returned by the tie() function, which would be useful if you want to
 access other methods in CLASSNAME.
 
-Note that functions such as keys() and values() may return huge array
-values when used on large objects, like DBM files.  You may prefer to
-use the each() function to iterate over such.  Example:
+Note that functions such as keys() and values() may return huge lists
+when used on large objects, like DBM files.  You may prefer to use the
+each() function to iterate over such.  Example:
 
     # print out history file offsets
     use NDBM_File;
@@ -3565,10 +3985,12 @@ Unlike dbmopen(), the tie() function will not use or require a module
 for you--you need to do that explicitly yourself.  See L<DB_File>
 or the F<Config> module for interesting tie() implementations.
 
+For further details see L<perltie>, L<tied VARIABLE>.
+
 =item tied VARIABLE
 
 Returns a reference to the object underlying VARIABLE (the same value
-that was originally returned by the tie() call which bound the variable
+that was originally returned by the tie() call that bound the variable
 to a package.)  Returns the undefined value if VARIABLE isn't tied to a
 package.
 
@@ -3581,14 +4003,14 @@ Suitable for feeding to gmtime() and localtime().
 
 =item times
 
-Returns a four-element array giving the user and system times, in
+Returns a four-element list giving the user and system times, in
 seconds, for this process and the children of this process.
 
     ($user,$system,$cuser,$csystem) = times;
 
 =item tr///
 
-The translation operator.  Same as y///. See L<perlop>.
+The transliteration operator.  Same as y///. See L<perlop>.
 
 =item truncate FILEHANDLE,LENGTH
 
@@ -3596,7 +4018,8 @@ The translation operator.  Same as y///. See L<perlop>.
 
 Truncates the file opened on FILEHANDLE, or named by EXPR, to the
 specified length.  Produces a fatal error if truncate isn't implemented
-on your system.
+on your system.  Returns TRUE if successful, the undefined value
+otherwise.
 
 =item uc EXPR
 
@@ -3623,7 +4046,8 @@ If EXPR is omitted, uses $_.
 =item umask
 
 Sets the umask for the process to EXPR and returns the previous value.
-If EXPR is omitted, merely returns the current umask.  Remember that a
+If EXPR is omitted, merely returns the current umask.  If umask(2) is
+not implemented on your system, returns C<undef>.  Remember that a
 umask is a number, usually given in octal; it is I<not> a string of octal
 digits.  See also L</oct>, if all you have is a string.
 
@@ -3632,23 +4056,27 @@ digits.  See also L</oct>, if all you have is a string.
 =item undef
 
 Undefines the value of EXPR, which must be an lvalue.  Use only on a
-scalar value, an entire array, an entire hash, or a subroutine name (using
-"&").  (Using undef() will probably not do what you expect on most
-predefined variables or DBM list values, so don't do that.)  Always
-returns the undefined value.  You can omit the EXPR, in which case
-nothing is undefined, but you still get an undefined value that you
-could, for instance, return from a subroutine, assign to a variable or
-pass as a parameter.  Examples:
+scalar value, an array (using "@"), a hash (using "%"), a subroutine
+(using "&"), or a typeglob (using "*").  (Saying C<undef $hash{$key}>
+will probably not do what you expect on most predefined variables or
+DBM list values, so don't do that; see L<delete>.)  Always returns the
+undefined value.  You can omit the EXPR, in which case nothing is
+undefined, but you still get an undefined value that you could, for
+instance, return from a subroutine, assign to a variable or pass as a
+parameter.  Examples:
 
     undef $foo;
     undef $bar{'blurfl'};             # Compare to: delete $bar{'blurfl'};
     undef @ary;
     undef %hash;
     undef &mysub;
+    undef *xyz;       # destroys $xyz, @xyz, %xyz, &xyz, etc.
     return (wantarray ? (undef, $errmsg) : undef) if $they_blew_it;
     select undef, undef, undef, 0.25;
     ($a, $b, undef, $c) = &foo;       # Ignore third value returned
 
+Note that this is a unary operator, not a list operator.
+
 =item unlink LIST
 
 =item unlink
@@ -3671,12 +4099,12 @@ If LIST is omitted, uses $_.
 
 Unpack does the reverse of pack: it takes a string representing a
 structure and expands it out into a list value, returning the array
-value.  (In a scalar context, it returns merely the first value
+value.  (In scalar context, it returns merely the first value
 produced.)  The TEMPLATE has the same format as in the pack function.
 Here's a subroutine that does substring:
 
     sub substr {
-	local($what,$where,$howmuch) = @_;
+	my($what,$where,$howmuch) = @_;
 	unpack("x$where a$howmuch", $what);
     }
 
@@ -3734,7 +4162,7 @@ If the first argument to C<use> is a number, it is treated as a version
 number instead of a module name.  If the version of the Perl interpreter
 is less than VERSION, then an error message is printed and Perl exits
 immediately.  This is often useful if you need to check the current
-Perl version before C<use>ing library modules which have changed in
+Perl version before C<use>ing library modules that have changed in
 incompatible ways from older versions of Perl.  (We try not to do
 this more than we have to.)
 
@@ -3755,7 +4183,7 @@ If you don't want your namespace altered, explicitly supply an empty list:
 
 That is exactly equivalent to
 
-    BEGIN { require Module; }
+    BEGIN { require Module }
 
 If the VERSION argument is present between Module and LIST, then the
 C<use> will call the VERSION method in class Module with the given
@@ -3773,9 +4201,10 @@ are also implemented this way.  Currently implemented pragmas are:
     use strict  qw(subs vars refs);
     use subs    qw(afunc blurfl);
 
-These pseudo-modules import semantics into the current block scope, unlike
-ordinary modules, which import symbols into the current package (which are
-effective through the end of the file).
+Some of these these pseudo-modules import semantics into the current
+block scope (like C<strict> or C<integer>, unlike ordinary modules,
+which import symbols into the current package (which are effective
+through the end of the file).
 
 There's a corresponding "no" command that unimports meanings imported
 by use, i.e., it calls C<unimport Module LIST> instead of C<import>.
@@ -3793,7 +4222,8 @@ Changes the access and modification times on each file of a list of
 files.  The first two elements of the list must be the NUMERICAL access
 and modification times, in that order.  Returns the number of files
 successfully changed.  The inode modification time of each file is set
-to the current time.  Example of a "touch" command:
+to the current time.  This code has the same effect as the "touch"
+command if the files already exist:
 
     #!/usr/bin/perl
     $now = time;
@@ -3801,11 +4231,12 @@ to the current time.  Example of a "touch" command:
 
 =item values HASH
 
-Returns a normal array consisting of all the values of the named hash.
-(In a scalar context, returns the number of values.)  The values are
-returned in an apparently random order, but it is the same order as either
-the keys() or each() function would produce on the same hash.  As a side
-effect, it resets HASH's iterator.  See also keys(), each(), and sort().
+Returns a list consisting of all the values of the named hash.  (In a
+scalar context, returns the number of values.)  The values are
+returned in an apparently random order, but it is the same order as
+either the keys() or each() function would produce on the same hash.
+As a side effect, it resets HASH's iterator.  See also keys(), each(),
+and sort().
 
 =item vec EXPR,OFFSET,BITS
 
@@ -3822,6 +4253,22 @@ Vectors created with vec() can also be manipulated with the logical
 operators |, &, and ^, which will assume a bit vector operation is
 desired when both operands are strings.
 
+The following code will build up an ASCII string saying 'PerlPerlPerl'.
+The comments show the string after each step. Note that this code works
+in the same way on big-endian or little-endian machines.
+
+    my $foo = '';
+    vec($foo,  0, 32) = 0x5065726C;	# 'Perl'
+    vec($foo,  2, 16) = 0x5065;		# 'PerlPe'
+    vec($foo,  3, 16) = 0x726C;		# 'PerlPerl'
+    vec($foo,  8,  8) = 0x50;		# 'PerlPerlP'
+    vec($foo,  9,  8) = 0x65;		# 'PerlPerlPe'
+    vec($foo, 20,  4) = 2;		# 'PerlPerlPe'   . "\x02"
+    vec($foo, 21,  4) = 7;		# 'PerlPerlPer'  # 'r' is "\x72"
+    vec($foo, 45,  2) = 3;		# 'PerlPerlPer'  . "\x0c"
+    vec($foo, 93,  1) = 1;		# 'PerlPerlPer'  . "\x2c"
+    vec($foo, 94,  1) = 1;		# 'PerlPerlPerl' # 'l' is "\x6c"
+
 To transform a bit vector into a string or array of 0's and 1's, use these:
 
     $bits = unpack("b*", $vector);
@@ -3842,7 +4289,7 @@ of the deceased process, or -1 if there is no such child process.  The
 status is returned in C<$?>.  If you say
 
     use POSIX ":sys_wait_h";
-    ...
+    #...
     waitpid(-1,&WNOHANG);
 
 then you can do a non-blocking wait for any process.  Non-blocking wait
@@ -3852,6 +4299,8 @@ FLAGS of 0 is implemented everywhere.  (Perl emulates the system call
 by remembering the status values of processes that have exited but have
 not been harvested by the Perl script yet.)
 
+See L<perlipc> for other examples.
+
 =item wantarray
 
 Returns TRUE if the context of the currently executing subroutine is
@@ -3868,6 +4317,13 @@ for no value (void context).
 Produces a message on STDERR just like die(), but doesn't exit or throw
 an exception.
 
+If LIST is empty and $@ already contains a value (typically from a
+previous eval) that value is used after appending "\t...caught"
+to $@. This is useful for staying almost, but not entirely similar to
+die().
+
+If $@ is empty then the string "Warning: Something's wrong" is used.
+
 No message is printed if there is a C<$SIG{__WARN__}> handler
 installed.  It is the handler's responsibility to deal with the message
 as it sees fit (like, for instance, converting it into a die()).  Most
@@ -3904,7 +4360,7 @@ examples.
 
 =item write
 
-Writes a formatted record (possibly multi-line) to the specified file,
+Writes a formatted record (possibly multi-line) to the specified FILEHANDLE,
 using the format associated with that file.  By default the format for
 a file is the one having the same name as the filehandle, but the
 format for the current output channel (see the select() function) may be set
@@ -3930,6 +4386,6 @@ Note that write is I<NOT> the opposite of read.  Unfortunately.
 
 =item y///
 
-The translation operator.  Same as tr///.  See L<perlop>.
+The transliteration operator.  Same as tr///.  See L<perlop>.
 
 =back