Contained in the file specified by the first filename on the command line.
(Note that systems supporting the C<#!> notation invoke interpreters this
-way. See L<Location of Perl>.)
+way. See L</Location of Perl>.)
=item 3.
a specific version of Perl, say, perl5.14.1, you should place
that directly in the C<#!> line's path.
-If the C<#!> line does not contain the word "perl" nor the word "indir"
+If the C<#!> line does not contain the word "perl" nor the word "indir",
the program named after the C<#!> is executed instead of the Perl
interpreter. This is slightly bizarre, but it helps people on machines
that don't do C<#!>, because they can tell a program that their SHELL is
#!/usr/bin/perl -spi.orig # same as -s -p -i.orig
+A C<--> signals the end of options and disables further option processing. Any
+arguments after the C<--> are treated as filenames and arguments.
+
Switches include:
=over 5
An alternate delimiter may be specified using B<-F>.
+B<-a> implicitly sets B<-n>.
+
=item B<-C [I<number/list>]>
X<-C>
in UTF-8
L 64 normally the "IOEioA" are unconditional, the L makes
them conditional on the locale environment variables
- (the LC_ALL, LC_TYPE, and LANG, in the order of
+ (the LC_ALL, LC_CTYPE, and LANG, in the order of
decreasing precedence) -- if the variables indicate
UTF-8, then the selected "IOEioA" are in effect
a 256 Set ${^UTF8CACHE} to -1, to run the UTF-8 caching
=item B<-D>I<number>
-sets debugging flags. To watch how it executes your program, use
-B<-Dtls>. (This works only if debugging is compiled into your
-Perl.) Another nice value is B<-Dx>, which lists your compiled
-syntax tree. And B<-Dr> displays compiled regular expressions;
-the format of the output is explained in L<perldebguts>.
+sets debugging flags. This switch is enabled only if your perl binary has
+been built with debugging enabled: normal production perls won't have
+been.
+
+For example, to watch how perl executes your program, use B<-Dtls>.
+Another nice value is B<-Dx>, which lists your compiled syntax tree, and
+B<-Dr> displays compiled regular expressions; the format of the output is
+explained in L<perldebguts>.
As an alternative, specify a number instead of list of letters (e.g.,
B<-D14> is equivalent to B<-Dtls>):
- 1 p Tokenizing and parsing (with v, displays parse stack)
- 2 s Stack snapshots (with v, displays all stacks)
- 4 l Context (loop) stack processing
- 8 t Trace execution
- 16 o Method and overloading resolution
- 32 c String/numeric conversions
- 64 P Print profiling info, source file input state
- 128 m Memory and SV allocation
- 256 f Format processing
- 512 r Regular expression parsing and execution
- 1024 x Syntax tree dump
- 2048 u Tainting checks
- 4096 U Unofficial, User hacking (reserved for private,
- unreleased use)
- 8192 H Hash dump -- usurps values()
- 16384 X Scratchpad allocation
- 32768 D Cleaning up
- 65536 S Op slab allocation
- 131072 T Tokenizing
- 262144 R Include reference counts of dumped variables (eg when
- using -Ds)
- 524288 J show s,t,P-debug (don't Jump over) on opcodes within
- package DB
- 1048576 v Verbose: use in conjunction with other flags
- 2097152 C Copy On Write
- 4194304 A Consistency checks on internal structures
- 8388608 q quiet - currently only suppresses the "EXECUTING"
- message
- 16777216 M trace smart match resolution
- 33554432 B dump suBroutine definitions, including special Blocks
- like BEGIN
+ 1 p Tokenizing and parsing (with v, displays parse
+ stack)
+ 2 s Stack snapshots (with v, displays all stacks)
+ 4 l Context (loop) stack processing
+ 8 t Trace execution
+ 16 o Method and overloading resolution
+ 32 c String/numeric conversions
+ 64 P Print profiling info, source file input state
+ 128 m Memory and SV allocation
+ 256 f Format processing
+ 512 r Regular expression parsing and execution
+ 1024 x Syntax tree dump
+ 2048 u Tainting checks
+ 4096 U Unofficial, User hacking (reserved for private,
+ unreleased use)
+ 8192 H Hash dump -- usurps values()
+ 16384 X Scratchpad allocation
+ 32768 D Cleaning up
+ 65536 S Op slab allocation
+ 131072 T Tokenizing
+ 262144 R Include reference counts of dumped variables
+ (eg when using -Ds)
+ 524288 J show s,t,P-debug (don't Jump over) on opcodes within
+ package DB
+ 1048576 v Verbose: use in conjunction with other flags
+ 2097152 C Copy On Write
+ 4194304 A Consistency checks on internal structures
+ 8388608 q quiet - currently only suppresses the "EXECUTING"
+ message
+ 16777216 M trace smart match resolution
+ 33554432 B dump suBroutine definitions, including special
+ Blocks like BEGIN
+ 67108864 L trace Locale-related info; what gets output is very
+ subject to change
+ 134217728 i trace PerlIO layer processing. Set PERLIO_DEBUG to
+ the filename to trace to.
All these flags require B<-DDEBUGGING> when you compile the Perl
executable (but see C<:opd> in L<Devel::Peek> or L<re/'debug' mode>
which may change this).
See the F<INSTALL> file in the Perl source distribution
-for how to do this. This flag is automatically set if you include B<-g>
-option when C<Configure> asks you about optimizer/debugger flags.
+for how to do this.
If you're just trying to get a print out of each line of Perl code
as it executes, the way that C<sh -x> provides for shell scripts,
=item B<-F>I<pattern>
X<-F>
-specifies the pattern to split on if B<-a> is also in effect. The
-pattern may be surrounded by C<//>, C<"">, or C<''>, otherwise it will be
-put in single quotes. You can't use literal whitespace in the pattern.
+specifies the pattern to split on for B<-a>. The pattern may be
+surrounded by C<//>, C<"">, or C<''>, otherwise it will be put in single
+quotes. You can't use literal whitespace in the pattern.
+
+B<-F> implicitly sets both B<-a> and B<-n>.
=item B<-h>
X<-h>
B<'-MI<MODULE> qw(foo bar)'>. This avoids the need to use quotes when
importing symbols. The actual code generated by B<-MI<MODULE>=foo,bar> is
C<use module split(/,/,q{foo,bar})>. Note that the C<=> form
-removes the distinction between B<-m> and B<-M>.
+removes the distinction between B<-m> and B<-M>; that is,
+B<-mI<MODULE>=foo,bar> is the same as B<-MI<MODULE>=foo,bar>.
A consequence of this is that B<-MI<MODULE>=number> never does a version check,
unless C<I<MODULE>::import()> itself is set up to do a version check, which
find . -mtime +7 -print | perl -nle unlink
This is faster than using the B<-exec> switch of I<find> because you don't
-have to start a process on every filename found. It does suffer from
-the bug of mishandling newlines in pathnames, which you can fix if
-you follow the example under B<-0>.
+have to start a process on every filename found (but it's not faster
+than using the B<-delete> switch available in newer versions of I<find>.
+It does suffer from the bug of mishandling newlines in pathnames, which
+you can fix if you follow the example under B<-0>.
C<BEGIN> and C<END> blocks may be used to capture control before or after
the implicit program loop, just as in I<awk>.
C<__WARN__> hooks, as described in L<perlvar> and L<perlfunc/warn>.
See also L<perldiag> and L<perltrap>. A fine-grained warning
facility is also available if you want to manipulate entire classes
-of warnings; see L<warnings> or L<perllexwarn>.
+of warnings; see L<warnings>.
=item B<-W>
X<-W>
Enables all warnings regardless of C<no warnings> or C<$^W>.
-See L<perllexwarn>.
+See L<warnings>.
=item B<-X>
X<-X>
Disables all warnings regardless of C<use warnings> or C<$^W>.
-See L<perllexwarn>.
+See L<warnings>.
=item B<-x>
X<-x>
=item PERLIO_DEBUG
X<PERLIO_DEBUG>
-If set to the name of a file or device, certain operations of PerlIO
-subsystem will be logged to that file, which is opened in append mode.
-Typical uses are in Unix:
+If set to the name of a file or device when Perl is run with the
+B<-Di> command-line switch, the logging of certain operations of
+the PerlIO subsystem will be redirected to the specified file rather
+than going to stderr, which is the default. The file is opened in append
+mode. Typical uses are in Unix:
- % env PERLIO_DEBUG=/dev/tty perl script ...
+ % env PERLIO_DEBUG=/tmp/perlio.log perl -Di script ...
and under Win32, the approximately equivalent:
> set PERLIO_DEBUG=CON
- perl script ...
+ perl -Di script ...
-This functionality is disabled for setuid scripts and for scripts run
-with B<-T>.
+This functionality is disabled for setuid scripts, for scripts run
+with B<-T>, and for scripts run on a Perl built without C<-DDEBUGGING>
+support.
=item PERLLIB
X<PERLLIB>
code. By manually setting a seed, this protection may be partially or
completely lost.
-See L<perlsec/"Algorithmic Complexity Attacks"> and L</PERL_PERTURB_KEYS>
+See L<perlsec/"Algorithmic Complexity Attacks">, L</PERL_PERTURB_KEYS>, and
L</PERL_HASH_SEED_DEBUG> for more information.
=item PERL_PERTURB_KEYS
An example output might be:
- HASH_FUNCTION = ONE_AT_A_TIME_HARD HASH_SEED = 0x652e9b9349a7a032 PERTURB_KEYS = 1 (RANDOM)
+ HASH_FUNCTION = ONE_AT_A_TIME_HARD HASH_SEED = 0x652e9b9349a7a032 PERTURB_KEYS = 1 (RANDOM)
=item PERL_MEM_LOG
X<PERL_MEM_LOG>
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