die "Can't cd to spool: $!\n" unless chdir '/usr/spool/news';
chdir '/usr/spool/news' or die "Can't cd to spool: $!\n"
-If the value of EXPR does not end in a newline, the current script line
-number and input line number (if any) are also printed, and a newline
-is supplied. Note that the "input line number" (also known as "chunk")
-is subject to whatever notion of "line" happens to be currently in
-effect, and is also available as the special variable C<$.>.
-See L<perlvar/"$/"> and L<perlvar/"$.">.
+If the last element of LIST does not end in a newline, the current
+script line number and input line number (if any) are also printed,
+and a newline is supplied. Note that the "input line number" (also
+known as "chunk") is subject to whatever notion of "line" happens to
+be currently in effect, and is also available as the special variable
+C<$.>. See L<perlvar/"$/"> and L<perlvar/"$.">.
-Hint: sometimes appending C<", stopped"> to your message
-will cause it to make better sense when the string C<"at foo line 123"> is
-appended. Suppose you are running script "canasta".
+Hint: sometimes appending C<", stopped"> to your message will cause it
+to make better sense when the string C<"at foo line 123"> is appended.
+Suppose you are running script "canasta".
die "/etc/games is no good";
die "/etc/games is no good, stopped";
C<< <> >> operator. Since C<< <> >> isn't explicitly opened,
as a normal filehandle is, an C<eof()> before C<< <> >> has been
used will cause C<@ARGV> to be examined to determine if input is
-available.
+available. Similarly, an C<eof()> after C<< <> >> has returned
+end-of-file will assume you are processing another C<@ARGV> list,
+and if you haven't set C<@ARGV>, will read input from C<STDIN>;
+see L<perlop/"I/O Operators">.
In a C<< while (<>) >> loop, C<eof> or C<eof(ARGV)> can be used to
detect the end of each file, C<eof()> will only detect the end of the
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
+=item no Module VERSION LIST
+
+=item no Module VERSION
+
=item no Module LIST
+=item no Module
+
See the L</use> function, which C<no> is the opposite of.
=item oct EXPR
IO buffers.) If you use the 3 arg form then you can pass either a number,
the name of a filehandle or the normal "reference to a glob".
-Here is a script that saves, redirects, and restores STDOUT and
-STDERR:
+Here is a script that saves, redirects, and restores C<STDOUT> and
+C<STDERR> using various methods:
#!/usr/bin/perl
- open(my $oldout, ">&", \*STDOUT);
- open(OLDERR, ">&STDERR");
-
- open(STDOUT, '>', "foo.out") || die "Can't redirect stdout";
- open(STDERR, ">&STDOUT") || die "Can't dup stdout";
+ open my $oldout, ">&STDOUT" or die "Can't dup STDOUT: $!";
+ open OLDERR, ">&", \*STDERR or die "Can't dup STDERR: $!";
+
+ open STDOUT, '>', "foo.out" or die "Can't redirect STDOUT: $!";
+ open STDERR, ">&STDOUT" or die "Can't dup STDOUT: $!";
- select(STDERR); $| = 1; # make unbuffered
- select(STDOUT); $| = 1; # make unbuffered
+ select STDERR; $| = 1; # make unbuffered
+ select STDOUT; $| = 1; # make unbuffered
print STDOUT "stdout 1\n"; # this works for
print STDERR "stderr 1\n"; # subprocesses too
- close(STDOUT);
- close(STDERR);
+ close STDOUT;
+ close STDERR;
- open(STDOUT, ">&OLDOUT");
- open(STDERR, ">&OLDERR");
+ open STDOUT, ">&", $oldout or die "Can't dup \$oldout: $!";
+ open STDERR, ">&OLDERR" or die "Can't dup OLDERR: $!";
print STDOUT "stdout 2\n";
print STDERR "stderr 2\n";
See L</seek> for some details about mixing reading and writing.
+=item opendir DIRHANDLE,MODE,EXPR
+
=item opendir DIRHANDLE,EXPR
Opens a directory named EXPR for processing by C<readdir>, C<telldir>,
C<seekdir>, C<rewinddir>, and C<closedir>. Returns true if successful.
DIRHANDLEs have their own namespace separate from FILEHANDLEs.
+In three-argument form the middle argument may be C<:utf8> to force
+the filenames returned by readdir() to be in UTF-8 encoding of Unicode.
+This naturally works only if your filesystem returns UTF-8 filenames.
+
=item ord EXPR
=item ord
unpack() C's C<struct {char c; double d; char cc[2]}> one may need to
use the template C<C x![d] d C[2]>; this assumes that doubles must be
aligned on the double's size.
-
+
For alignment commands C<count> of 0 is equivalent to C<count> of 1;
both result in no-ops.
-
+
=item *
A comment in a TEMPLATE starts with C<#> and goes to the end of line.
@dots = grep { /^\./ && -f "$some_dir/$_" } readdir(DIR);
closedir DIR;
+In some filesystems it is possible to return UTF-8 encoded filenames.
+To get readdir() to return such filenames, you must use C<:utf8> with
+the three-argument form of opendir(), see L</opendir>.
+
=item readline EXPR
Reads from the filehandle whose typeglob is contained in EXPR. In scalar
use sort 'stable';
@new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
- # force use of quicksort (not portable outside Perl 5.8)
- use sort '_quicksort'; # note discouraging _
+ # force use of mergesort (not portable outside Perl 5.8)
+ use sort '_mergesort'; # note discouraging _
@new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
- # similar to the previous example, but demand stability as well
- use sort qw( _mergesort stable );
+ # Similar to the previous example, but demand stability as well
+ # Because of the way quicksort is "stabilized", this combination
+ # is not threadsafe
+ use sort qw( _quicksort stable );
@new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
If you're using strict, you I<must not> declare $a
removed. The array grows or shrinks as necessary.
If OFFSET is negative then it starts that far from the end of the array.
If LENGTH is omitted, removes everything from OFFSET onward.
-If LENGTH is negative, leaves that many elements off the end of the array.
+If LENGTH is negative, removes the elements from OFFSET onward
+except for -LENGTH elements at the end of the array.
If both OFFSET and LENGTH are omitted, removes everything. If OFFSET is
past the end of the array, perl issues a warning, and splices at the
end of the array.
projects / p5sagit/p5-mst-13.2.git / blobdiff