S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]>
S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ] [ B<-f> ]>
S<[ B<-C [I<number/list>] >]>
- S<[ B<-P> ]>
S<[ B<-S> ]>
S<[ B<-x>[I<dir>] ]>
S<[ B<-i>[I<extension>] ]>
- S<[
B<-eE> I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
+ S<[
[B<-e>|B<-E>] I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
=head1 DESCRIPTION
The sequences "-*" and "- " are specifically ignored so that you could,
if you were so inclined, say
- #!/bin/sh -- # -*- perl -*- -p
- eval 'exec perl -wS $0 ${1+"$@"}'
- if $running_under_some_shell;
+ #!/bin/sh
+ #! -*-perl-*-
+ eval 'exec perl -x -wS $0 ${1+"$@"}'
+ if 0;
to let Perl see the B<-p> switch.
=item B<-C [I<number/list>]>
X<-C>
-The C<-C> flag controls some Unicode of the Perl Unicode features.
+The C<-C> flag controls some of the Perl Unicode features.
As of 5.8.1, the C<-C> can be followed either by a number or a list
of option letters. The letters, their numeric values, and effects
This feature was practically unused, however, and the command line
switch was therefore "recycled".)
+B<Note:> Since perl 5.10.0, the -C option can no longer be used
+on the #! line. It wasn't working there anyway, since the standard streams
+are already set up at this point in the execution of the perl interpreter.
+You can use binmode() instead to get the desired behaviour.
+
=item B<-c>
X<-c>
8 t Trace execution
16 o Method and overloading resolution
32 c String/numeric conversions
- 64 P Print profiling info, preprocessor command for -P, source file input state
- 128 m Memory allocation
+ 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
8192 H Hash dump -- usurps values()
16384 X Scratchpad allocation
32768 D Cleaning up
- 65536 S Thread synchronization
131072 T Tokenising
262144 R Include reference counts of dumped variables (eg when using -Ds)
524288 J Do not s,t,P-debug (Jump over) opcodes within package DB
Disable executing F<$Config{sitelib}/sitecustomize.pl> at startup.
Perl can be built so that it by default will try to execute
-F<$Config{sitelib}/sitecustomize.pl> at startup. This is a hook that
-allows the sysadmin to customize how perl behaves. It can for
-instance be used to add entries to the @INC array to make perl find
-modules in non-standard locations.
+F<$Config{sitelib}/sitecustomize.pl> at startup (in a BEGIN block).
+This is a hook that allows the sysadmin to customize how perl behaves.
+It can for instance be used to add entries to the @INC array to make perl
+find modules in non-standard locations.
=item B<-F>I<pattern>
X<-F>
X<-I> X<@INC>
Directories specified by B<-I> are prepended to the search path for
-modules (C<@INC>), and also tells the C preprocessor where to search for
-include files. The C preprocessor is invoked with B<-P>; by default it
-searches /usr/include and /usr/lib/perl.
+modules (C<@INC>).
=item B<-l>[I<octnum>]
X<-l> X<$/> X<$\>
lines printed. If a file named by an argument cannot be opened for
some reason, Perl warns you about it and moves on to the next file.
+Also note that C<< <> >> passes command line arguments to
+L<perlfunc/open>, which doesn't necessarily interpret them as file names.
+See L<perlop> for possible security implications.
+
Here is an efficient way to delete all files that haven't been modified for
at least a week:
C<BEGIN> and C<END> blocks may be used to capture control before or after
the implicit loop, just as in B<awk>.
-=item B<-P>
-X<-P>
-
-B<NOTE: Use of -P is strongly discouraged because of its inherent
-problems, including poor portability.>
-
-This option causes your program to be run through the C preprocessor before
-compilation by Perl. Because both comments and B<cpp> directives begin
-with the # character, you should avoid starting comments with any words
-recognized by the C preprocessor such as C<"if">, C<"else">, or C<"define">.
-
-If you're considering using C<-P>, you might also want to look at the
-Filter::cpp module from CPAN.
-
-The problems of -P include, but are not limited to:
-
-=over 10
-
-=item *
-
-The C<#!> line is stripped, so any switches there don't apply.
-
-=item *
-
-A C<-P> on a C<#!> line doesn't work.
-
-=item *
-
-B<All> lines that begin with (whitespace and) a C<#> but
-do not look like cpp commands, are stripped, including anything
-inside Perl strings, regular expressions, and here-docs .
-
-=item *
-
-In some platforms the C preprocessor knows too much: it knows about
-the C++ -style until-end-of-line comments starting with C<"//">.
-This will cause problems with common Perl constructs like
-
- s/foo//;
-
-because after -P this will became illegal code
-
- s/foo
-
-The workaround is to use some other quoting separator than C<"/">,
-like for example C<"!">:
-
- s!foo!!;
-
-
-
-=item *
-
-It requires not only a working C preprocessor but also a working
-F<sed>. If not on UNIX, you are probably out of luck on this.
-
-=item *
-
-Script line numbers are not preserved.
-
-=item *
-
-The C<-x> does not work with C<-P>.
-
-=back
-
=item B<-s>
X<-s>
operator instead. Note: availability of B<undump> is platform
specific and may not be available for a specific port of Perl.
-This switch has been superseded in favor of the new Perl code
-generator backends to the compiler. See L<B> and L<B::Bytecode>
-for details.
-
=item B<-U>
X<-U>
=item B<-x>
X<-x>
-=item B<-x> I<directory>
+=item B<-x>I<directory>
tells Perl that the program is embedded in a larger chunk of unrelated
ASCII text, such as in a mail message. Leading garbage will be
discarded until the first line that starts with #! and contains the
string "perl". Any meaningful switches on that line will be applied.
+
+All references to line numbers by the program (warnings, errors, ...)
+will treat the #! line as the first line.
+Thus a warning on the 2nd line of the program (which is on the 100th
+line in the file) will be reported as line 2, and not as line 100.
+This can be overridden by using the #line directive.
+(See L<perlsyn/"Plain-Old-Comments-(Not!)">)
+
If a directory name is specified, Perl will switch to that directory
before running the program. The B<-x> switch controls only the
disposal of leading garbage. The program must be terminated with
can process any or all of the trailing garbage via the DATA filehandle
if desired).
+The directory, if specified, must appear immediately following the B<-x>
+with no intervening whitespace.
+
=back
=head1 ENVIRONMENT
X<PERL5OPT>
Command-line options (switches). Switches in this variable are taken
-as if they were on every Perl command line. Only the B<-[CDIMUdmtwA]>
+as if they were on every Perl command line. Only the B<-[CDIMUdmtwW]>
switches are allowed. When running taint checks (because the program
was running setuid or setgid, or the B<-T> switch was used), this
variable is ignored. If PERL5OPT begins with B<-T>, tainting will be
A pseudolayer that turns on a flag on the layer below to tell perl
that output should be in utf8 and that input should be regarded as
-already in utf8 form. May be useful in PERLIO environment
-variable to make UTF-8 the default. (To turn off that behaviour
-use C<:bytes> layer.)
+already in valid utf8 form. It does not check for validity and as such
+should be handled with caution for input. Generally C<:encoding(utf8)> is
+the best option when reading UTF-8 encoded data.
=item :win32
X<:win32>
C<win32> layer which is expected to be enhanced and should eventually be
the default under Win32.
+The PERLIO environment variable is completely ignored when perl
+is run in taint mode.
+
=item PERLIO_DEBUG
X<PERLIO_DEBUG>
files before looking in the standard library and the current directory.
If PERL5LIB is defined, PERLLIB is not used.
+The PERLLIB environment variable is completely ignored when perl
+is run in taint mode.
+
=item PERL5DB
X<PERL5DB>
BEGIN { require 'perl5db.pl' }
+The PERL5DB environment variable only used when perl is started with
+a bare B<-d> switch.
+
=item PERL5DB_THREADED
X<PERL5DB_THREADED>
interfere with the proper functioning of other programs (which usually
look in COMSPEC to find a shell fit for interactive use).
+Before Perl 5.10.0 and 5.8.8, PERL5SHELL was not taint checked
+when running external commands. It is recommended that
+you explicitly set (or delete) C<$ENV{PERL5SHELL}> when running
+in taint mode under Windows.
+
=item PERL_ALLOW_NON_IFS_LSP (specific to the Win32 port)
X<PERL_ALLOW_NON_IFS_LSP>
=item PERL_HASH_SEED
X<PERL_HASH_SEED>
-(Since Perl 5.8.1.) Used to randomise Perl's internal hash function.
+(Since Perl 5.8.1.) Used to randomise perl's internal hash function.
To emulate the pre-5.8.1 behaviour, set to an integer (zero means
exactly the same order as 5.8.0). "Pre-5.8.1" means, among other
-things, that hash keys will be ordered the same between different runs
-of Perl.
+things, that hash keys will always have the same ordering between
+different runs of perl.
+
+Most hashes return elements in the same order as Perl 5.8.0 by default.
+On a hash by hash basis, if pathological data is detected during a hash
+key insertion, then that hash will switch to an alternative random hash
+seed.
The default behaviour is to randomise unless the PERL_HASH_SEED is set.
-If Perl has been compiled with C<-DUSE_HASH_SEED_EXPLICIT>, the default
+If perl has been compiled with C<-DUSE_HASH_SEED_EXPLICIT>, the default
behaviour is B<not> to randomise unless the PERL_HASH_SEED is set.
-If PERL_HASH_SEED is unset or set to a non-numeric string, Perl uses
+If PERL_HASH_SEED is unset or set to a non-numeric string, perl uses
the pseudorandom seed supplied by the operating system and libraries.
-This means that each different run of Perl will have a different
-ordering of the results of keys(), values(), and each().
B<Please note that the hash seed is sensitive information>. Hashes are
randomized to protect against local and remote attacks against Perl
https://perl5.git.perl.org / perl5.git / blobdiff