=item Keywords related to scoping
-C<caller>, C<import>, C<local>, C<my>, C<package>, C<use>
+C<caller>, C<import>, C<local>, C<my>, C<our>, C<package>, C<use>
=item Miscellaneous functions
-C<defined>, C<dump>, C<eval>, C<formline>, C<local>, C<my>, C<reset>,
+C<defined>, C<dump>, C<eval>, C<formline>, C<local>, C<my>, C<our>, C<reset>,
C<scalar>, C<undef>, C<wantarray>
=item Functions for processes and process groups
=item Functions new in perl5
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<import>, C<lc>, C<lcfirst>, C<map>, C<my>, C<no>, C<our>, 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
Another consequence of using binmode() (on some systems) is that
special end-of-file markers will be seen as part of the data stream.
For systems from the Microsoft family this means that if your binary
-data contains C<\cZ>, the I/O subsystem will ragard it as the end of
+data contains C<\cZ>, the I/O subsystem will regard it as the end of
the file, unless you use binmode().
binmode() is not only important for readline() and print() operations,
die() can also be called with a reference argument. If this happens to be
trapped within an eval(), $@ contains the reference. This behavior permits
a more elaborate exception handling implementation using objects that
-maintain arbitary state about the nature of the exception. Such a scheme
+maintain arbitrary state about the nature of the exception. Such a scheme
is sometimes preferable to matching particular string values of $@ using
regular expressions. Here's an example:
the real name of the user (as opposed to the login name) and other
information pertaining to the user. Beware, however, that in many
system users are able to change this information and therefore it
-cannot be trusted and therefore the $gcos is is tainted (see
+cannot be trusted and therefore the $gcos is tainted (see
L<perlsec>). The $passwd and $shell, user's encrypted password and
login shell, are also tainted, because of the same reason.
C<d_pwchange>, C<d_pwcomment>, and C<d_pwexpire>. Shadow password
files are only supported if your vendor has implemented them in the
intuitive fashion that calling the regular C library routines gets the
-shadow versions if you're running under privilege. Those that
-incorrectly implement a separate library call are not supported.
+shadow versions if you're running under privilege or if there exists
+the shadow(3) functions as found in System V ( this includes Solaris
+and Linux.) Those systems which implement a proprietary shadow password
+facility are unlikely to be supported.
The $members value returned by I<getgr*()> is a space separated list of
the login names of the members of the group.
indicating December. $year is the number of years since 1900. That
is, $year is C<123> in year 2023. $wday is the day of the week, with
0 indicating Sunday and 3 indicating Wednesday. $yday is the day of
-the year, in the range C<1..365> (or C<1..366> in leap years.)
+the year, in the range C<0..364> (or C<0..365> in leap years.)
Note that the $year element is I<not> simply the last two digits of
the year. If you assume it is, then you create non-Y2K-compliant
print $key, '=', $ENV{$key}, "\n";
}
+The returned values are copies of the original keys in the hash, so
+modifying them will not affect the original hash. Compare L</values>.
+
To sort a hash by value, you'll need to use a C<sort> function.
Here's a descending numeric sort of a hash by its values:
indicating December. $year is the number of years since 1900. That
is, $year is C<123> in year 2023. $wday is the day of the week, with
0 indicating Sunday and 3 indicating Wednesday. $yday is the day of
-the year, in the range C<1..365> (or C<1..366> in leap years.) $isdst
+the year, in the range C<0..364> (or C<0..365> in leap years.) $isdst
is true if the specified time occurs during daylight savings time,
false otherwise.
id, or the undefined value if there is an error. See also C<IPC::SysV>
and C<IPC::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 native long integer message
-type, which may be created with C<pack("l!", $type)>. Returns true if
-successful, or false if there is an error. See also C<IPC::SysV> and
-C<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. See also C<IPC::SysV> and C<IPC::SysV::Msg> documentation.
+SIZE. Note that when a message is received, the message type as a
+native long integer will be the first thing in VAR, followed by the
+actual message. This packing may be opened with C<unpack("l! a*")>.
+Taints the variable. Returns true if successful, or false if there is
+an error. See also C<IPC::SysV> and C<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 native long integer message
+type, and be followed by the length of the actual message, and finally
+the message itself. This kind of packing can be achieved with
+C<pack("l! a*", $type, $message)>. Returns true if successful,
+or false if there is an error. See also C<IPC::SysV>
+and C<IPC::SysV::Msg> documentation.
=item my EXPR
Opens the file whose filename is given by EXPR, and associates it with
FILEHANDLE. If FILEHANDLE is an expression, its value is used as the
-name of the real filehandle wanted. If EXPR is omitted, the scalar
+name of the real filehandle wanted. (This is considered a symbolic
+reference, so C<use strict 'refs'> should I<not> be in effect.)
+
+If EXPR is omitted, the scalar
variable of the same name as the FILEHANDLE contains the filename.
(Note that lexical variables--those declared with C<my>--will not work
for this purpose; so if you're using C<my>, specify EXPR in your call
open(FOO, "< $file\0");
(this may not work on some bizzare filesystems). One should
-conscientiously choose between the the I<magic> and 3-arguments form
+conscientiously choose between the I<magic> and 3-arguments form
of open():
open IN, $ARGV[0];
follows:
a A string with arbitrary binary data, will be null padded.
- A An ascii string, will be space padded.
+ A An ASCII string, will be space padded.
Z A null terminated (asciz) string, will be null padded.
b A bit string (ascending bit order inside each byte, like vec()).
semid_ds structure or semaphore value array. Returns like C<ioctl>:
the undefined value for error, "C<0 but true>" for zero, or the actual
return value otherwise. The ARG must consist of a vector of native
-short integers, which may may be created with C<pack("s!",(0)x$nsem)>.
+short integers, which may be created with C<pack("s!",(0)x$nsem)>.
See also C<IPC::SysV> and C<IPC::Semaphore> documentation.
=item semget KEY,NSEMS,FLAGS
the C<eval ''>, C<BEGIN {}>, C<INIT {}>, C<CHECK {}>, and C<END {}>
constructs.
-See also C<unshift>, C<push>, and C<pop>. C<Shift()> and C<unshift> do the
+See also C<unshift>, C<push>, and C<pop>. C<shift()> and C<unshift> do the
same thing to the left end of an array that C<pop> and C<push> do to the
right end.
and the S_IF* functions are
- S_IFMODE($mode) the part of $mode containg the permission bits
+ S_IFMODE($mode) the part of $mode containing the permission bits
and the setuid/setgid/sticky bits
S_IFMT($mode) the part of $mode containing the file type
be the same order as either the C<keys> or C<each> function would
produce on the same (unmodified) hash.
-Note that you cannot modify the values of a hash this way, because the
-returned list is just a copy. You need to use a hash slice for that,
-since it's lvaluable in a way that values() is not.
+Note that the values are not copied, which means modifying them will
+modify the contents of the hash:
- for (values %hash) { s/foo/bar/g } # FAILS!
- for (@hash{keys %hash}) { s/foo/bar/g } # ok
+ for (values %hash) { s/foo/bar/g } # modifies %hash values
+ for (@hash{keys %hash}) { s/foo/bar/g } # same
As a side effect, calling values() resets the HASH's internal iterator.
See also C<keys>, C<each>, and C<sort>.
projects / p5sagit/p5-mst-13.2.git / blobdiff