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diff --git a/contrib/perl5/pod/perlrun.pod b/contrib/perl5/pod/perlrun.pod deleted file mode 100644 index 30e82fc..0000000 --- a/contrib/perl5/pod/perlrun.pod +++ /dev/null @@ -1,859 +0,0 @@ -=head1 NAME - -perlrun - how to execute the Perl interpreter - -=head1 SYNOPSIS - -B<perl> S<[ B<-CsTuUWX> ]> - S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]> - S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]> - S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]> - S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]> - S<[ B<-P> ]> - S<[ B<-S> ]> - S<[ B<-x>[I<dir>] ]> - S<[ B<-i>[I<extension>] ]> - S<[ B<-e> I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...> - -=head1 DESCRIPTION - -The normal way to run a Perl program is by making it directly -executable, or else by passing the name of the source file as an -argument on the command line. (An interactive Perl environment -is also possible--see L<perldebug> for details on how to do that.) -Upon startup, Perl looks for your program in one of the following -places: - -=over 4 - -=item 1. - -Specified line by line via B<-e> switches on the command line. - -=item 2. - -Contained in the file specified by the first filename on the command line. -(Note that systems supporting the #! notation invoke interpreters this -way. See L<Location of Perl>.) - -=item 3. - -Passed in implicitly via standard input. This works only if there are -no filename arguments--to pass arguments to a STDIN-read program you -must explicitly specify a "-" for the program name. - -=back - -With methods 2 and 3, Perl starts parsing the input file from the -beginning, unless you've specified a B<-x> switch, in which case it -scans for the first line starting with #! and containing the word -"perl", and starts there instead. This is useful for running a program -embedded in a larger message. (In this case you would indicate the end -of the program using the C<__END__> token.) - -The #! line is always examined for switches as the line is being -parsed. Thus, if you're on a machine that allows only one argument -with the #! line, or worse, doesn't even recognize the #! line, you -still can get consistent switch behavior regardless of how Perl was -invoked, even if B<-x> was used to find the beginning of the program. - -Because historically some operating systems silently chopped off -kernel interpretation of the #! line after 32 characters, some -switches may be passed in on the command line, and some may not; -you could even get a "-" without its letter, if you're not careful. -You probably want to make sure that all your switches fall either -before or after that 32-character boundary. Most switches don't -actually care if they're processed redundantly, but getting a "-" -instead of a complete switch could cause Perl to try to execute -standard input instead of your program. And a partial B<-I> switch -could also cause odd results. - -Some switches do care if they are processed twice, for instance -combinations of B<-l> and B<-0>. Either put all the switches after -the 32-character boundary (if applicable), or replace the use of -B<-0>I<digits> by C<BEGIN{ $/ = "\0digits"; }>. - -Parsing of the #! switches starts wherever "perl" is mentioned in the line. -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; - -to let Perl see the B<-p> switch. - -A similar trick involves the B<env> program, if you have it. - - #!/usr/bin/env perl - -The examples above use a relative path to the perl interpreter, -getting whatever version is first in the user's path. If you want -a specific version of Perl, say, perl5.005_57, you should place -that directly in the #! line's path. - -If the #! line does not contain the word "perl", the program named after -the #! is executed instead of the Perl interpreter. This is slightly -bizarre, but it helps people on machines that don't do #!, because they -can tell a program that their SHELL is F</usr/bin/perl>, and Perl will then -dispatch the program to the correct interpreter for them. - -After locating your program, Perl compiles the entire program to an -internal form. If there are any compilation errors, execution of the -program is not attempted. (This is unlike the typical shell script, -which might run part-way through before finding a syntax error.) - -If the program is syntactically correct, it is executed. If the program -runs off the end without hitting an exit() or die() operator, an implicit -C<exit(0)> is provided to indicate successful completion. - -=head2 #! and quoting on non-Unix systems - -Unix's #! technique can be simulated on other systems: - -=over 4 - -=item OS/2 - -Put - - extproc perl -S -your_switches - -as the first line in C<*.cmd> file (B<-S> due to a bug in cmd.exe's -`extproc' handling). - -=item MS-DOS - -Create a batch file to run your program, and codify it in -C<ALTERNATIVE_SHEBANG> (see the F<dosish.h> file in the source -distribution for more information). - -=item Win95/NT - -The Win95/NT installation, when using the ActiveState installer for Perl, -will modify the Registry to associate the F<.pl> extension with the perl -interpreter. If you install Perl by other means (including building from -the sources), you may have to modify the Registry yourself. Note that -this means you can no longer tell the difference between an executable -Perl program and a Perl library file. - -=item Macintosh - -A Macintosh perl program will have the appropriate Creator and -Type, so that double-clicking them will invoke the perl application. - -=item VMS - -Put - - $ perl -mysw 'f$env("procedure")' 'p1' 'p2' 'p3' 'p4' 'p5' 'p6' 'p7' 'p8' ! - $ exit++ + ++$status != 0 and $exit = $status = undef; - -at the top of your program, where B<-mysw> are any command line switches you -want to pass to Perl. You can now invoke the program directly, by saying -C<perl program>, or as a DCL procedure, by saying C<@program> (or implicitly -via F<DCL$PATH> by just using the name of the program). - -This incantation is a bit much to remember, but Perl will display it for -you if you say C<perl "-V:startperl">. - -=back - -Command-interpreters on non-Unix systems have rather different ideas -on quoting than Unix shells. You'll need to learn the special -characters in your command-interpreter (C<*>, C<\> and C<"> are -common) and how to protect whitespace and these characters to run -one-liners (see B<-e> below). - -On some systems, you may have to change single-quotes to double ones, -which you must I<not> do on Unix or Plan9 systems. You might also -have to change a single % to a %%. - -For example: - - # Unix - perl -e 'print "Hello world\n"' - - # MS-DOS, etc. - perl -e "print \"Hello world\n\"" - - # Macintosh - print "Hello world\n" - (then Run "Myscript" or Shift-Command-R) - - # VMS - perl -e "print ""Hello world\n""" - -The problem is that none of this is reliable: it depends on the -command and it is entirely possible neither works. If B<4DOS> were -the command shell, this would probably work better: - - perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>"" - -B<CMD.EXE> in Windows NT slipped a lot of standard Unix functionality in -when nobody was looking, but just try to find documentation for its -quoting rules. - -Under the Macintosh, it depends which environment you are using. The MacPerl -shell, or MPW, is much like Unix shells in its support for several -quoting variants, except that it makes free use of the Macintosh's non-ASCII -characters as control characters. - -There is no general solution to all of this. It's just a mess. - -=head2 Location of Perl - -It may seem obvious to say, but Perl is useful only when users can -easily find it. When possible, it's good for both F</usr/bin/perl> -and F</usr/local/bin/perl> to be symlinks to the actual binary. If -that can't be done, system administrators are strongly encouraged -to put (symlinks to) perl and its accompanying utilities into a -directory typically found along a user's PATH, or in some other -obvious and convenient place. - -In this documentation, C<#!/usr/bin/perl> on the first line of the program -will stand in for whatever method works on your system. You are -advised to use a specific path if you care about a specific version. - - #!/usr/local/bin/perl5.00554 - -or if you just want to be running at least version, place a statement -like this at the top of your program: - - use 5.005_54; - -=head2 Command Switches - -As with all standard commands, a single-character switch may be -clustered with the following switch, if any. - - #!/usr/bin/perl -spi.orig # same as -s -p -i.orig - -Switches include: - -=over 5 - -=item B<-0>[I<digits>] - -specifies the input record separator (C<$/>) as an octal number. If there are -no digits, the null character is the separator. Other switches may -precede or follow the digits. For example, if you have a version of -B<find> which can print filenames terminated by the null character, you -can say this: - - find . -name '*.orig' -print0 | perl -n0e unlink - -The special value 00 will cause Perl to slurp files in paragraph mode. -The value 0777 will cause Perl to slurp files whole because there is no -legal character with that value. - -=item B<-a> - -turns on autosplit mode when used with a B<-n> or B<-p>. An implicit -split command to the @F array is done as the first thing inside the -implicit while loop produced by the B<-n> or B<-p>. - - perl -ane 'print pop(@F), "\n";' - -is equivalent to - - while (<>) { - @F = split(' '); - print pop(@F), "\n"; - } - -An alternate delimiter may be specified using B<-F>. - -=item B<-C> - -enables Perl to use the native wide character APIs on the target system. -The magic variable C<${^WIDE_SYSTEM_CALLS}> reflects the state of -this switch. See L<perlvar/"${^WIDE_SYSTEM_CALLS}">. - -This feature is currently only implemented on the Win32 platform. - -=item B<-c> - -causes Perl to check the syntax of the program and then exit without -executing it. Actually, it I<will> execute C<BEGIN>, C<CHECK>, and -C<use> blocks, because these are considered as occurring outside the -execution of your program. C<INIT> and C<END> blocks, however, will -be skipped. - -=item B<-d> - -runs the program under the Perl debugger. See L<perldebug>. - -=item B<-d:>I<foo[=bar,baz]> - -runs the program under the control of a debugging, profiling, or -tracing module installed as Devel::foo. E.g., B<-d:DProf> executes -the program using the Devel::DProf profiler. As with the B<-M> -flag, options may be passed to the Devel::foo package where they -will be received and interpreted by the Devel::foo::import routine. -The comma-separated list of options must follow a C<=> character. -See L<perldebug>. - -=item B<-D>I<letters> - -=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. 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 - 2 s Stack snapshots - 4 l Context (loop) stack processing - 8 t Trace execution - 16 o Method and overloading resolution - 32 c String/numeric conversions - 64 P Print preprocessor command for -P, source file input state - 128 m Memory allocation - 256 f Format processing - 512 r Regular expression parsing and execution - 1024 x Syntax tree dump - 2048 u Tainting checks - 4096 L Memory leaks (needs -DLEAKTEST when compiling Perl) - 8192 H Hash dump -- usurps values() - 16384 X Scratchpad allocation - 32768 D Cleaning up - 65536 S Thread synchronization - 131072 T Tokenising - -All these flags require B<-DDEBUGGING> when you compile the Perl -executable. 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. - -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, -you can't use Perl's B<-D> switch. Instead do this - - # Bourne shell syntax - $ PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program - - # csh syntax - % (setenv PERLDB_OPTS "NonStop=1 AutoTrace=1 frame=2"; perl -dS program) - -See L<perldebug> for details and variations. - -=item B<-e> I<commandline> - -may be used to enter one line of program. If B<-e> is given, Perl -will not look for a filename in the argument list. Multiple B<-e> -commands may be given to build up a multi-line script. Make sure -to use semicolons where you would in a normal program. - -=item B<-F>I<pattern> - -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. - -=item B<-h> - -prints a summary of the options. - -=item B<-i>[I<extension>] - -specifies that files processed by the C<E<lt>E<gt>> construct are to be -edited in-place. It does this by renaming the input file, opening the -output file by the original name, and selecting that output file as the -default for print() statements. The extension, if supplied, is used to -modify the name of the old file to make a backup copy, following these -rules: - -If no extension is supplied, no backup is made and the current file is -overwritten. - -If the extension doesn't contain a C<*>, then it is appended to the -end of the current filename as a suffix. If the extension does -contain one or more C<*> characters, then each C<*> is replaced -with the current filename. In Perl terms, you could think of this -as: - - ($backup = $extension) =~ s/\*/$file_name/g; - -This allows you to add a prefix to the backup file, instead of (or in -addition to) a suffix: - - $ perl -pi 'orig_*' -e 's/bar/baz/' fileA # backup to 'orig_fileA' - -Or even to place backup copies of the original files into another -directory (provided the directory already exists): - - $ perl -pi 'old/*.orig' -e 's/bar/baz/' fileA # backup to 'old/fileA.orig' - -These sets of one-liners are equivalent: - - $ perl -pi -e 's/bar/baz/' fileA # overwrite current file - $ perl -pi '*' -e 's/bar/baz/' fileA # overwrite current file - - $ perl -pi '.orig' -e 's/bar/baz/' fileA # backup to 'fileA.orig' - $ perl -pi '*.orig' -e 's/bar/baz/' fileA # backup to 'fileA.orig' - -From the shell, saying - - $ perl -p -i.orig -e "s/foo/bar/; ... " - -is the same as using the program: - - #!/usr/bin/perl -pi.orig - s/foo/bar/; - -which is equivalent to - - #!/usr/bin/perl - $extension = '.orig'; - LINE: while (<>) { - if ($ARGV ne $oldargv) { - if ($extension !~ /\*/) { - $backup = $ARGV . $extension; - } - else { - ($backup = $extension) =~ s/\*/$ARGV/g; - } - rename($ARGV, $backup); - open(ARGVOUT, ">$ARGV"); - select(ARGVOUT); - $oldargv = $ARGV; - } - s/foo/bar/; - } - continue { - print; # this prints to original filename - } - select(STDOUT); - -except that the B<-i> form doesn't need to compare $ARGV to $oldargv to -know when the filename has changed. It does, however, use ARGVOUT for -the selected filehandle. Note that STDOUT is restored as the default -output filehandle after the loop. - -As shown above, Perl creates the backup file whether or not any output -is actually changed. So this is just a fancy way to copy files: - - $ perl -p -i '/some/file/path/*' -e 1 file1 file2 file3... -or - $ perl -p -i '.orig' -e 1 file1 file2 file3... - -You can use C<eof> without parentheses to locate the end of each input -file, in case you want to append to each file, or reset line numbering -(see example in L<perlfunc/eof>). - -If, for a given file, Perl is unable to create the backup file as -specified in the extension then it will skip that file and continue on -with the next one (if it exists). - -For a discussion of issues surrounding file permissions and B<-i>, -see L<perlfaq5/Why does Perl let me delete read-only files? Why does -i clobber protected files? Isn't this a bug in Perl?>. - -You cannot use B<-i> to create directories or to strip extensions from -files. - -Perl does not expand C<~> in filenames, which is good, since some -folks use it for their backup files: - - $ perl -pi~ -e 's/foo/bar/' file1 file2 file3... - -Finally, the B<-i> switch does not impede execution when no -files are given on the command line. In this case, no backup is made -(the original file cannot, of course, be determined) and processing -proceeds from STDIN to STDOUT as might be expected. - -=item B<-I>I<directory> - -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. - -=item B<-l>[I<octnum>] - -enables automatic line-ending processing. It has two separate -effects. First, it automatically chomps C<$/> (the input record -separator) when used with B<-n> or B<-p>. Second, it assigns C<$\> -(the output record separator) to have the value of I<octnum> so -that any print statements will have that separator added back on. -If I<octnum> is omitted, sets C<$\> to the current value of -C<$/>. For instance, to trim lines to 80 columns: - - perl -lpe 'substr($_, 80) = ""' - -Note that the assignment C<$\ = $/> is done when the switch is processed, -so the input record separator can be different than the output record -separator if the B<-l> switch is followed by a B<-0> switch: - - gnufind / -print0 | perl -ln0e 'print "found $_" if -p' - -This sets C<$\> to newline and then sets C<$/> to the null character. - -=item B<-m>[B<->]I<module> - -=item B<-M>[B<->]I<module> - -=item B<-M>[B<->]I<'module ...'> - -=item B<-[mM]>[B<->]I<module=arg[,arg]...> - -B<-m>I<module> executes C<use> I<module> C<();> before executing your -program. - -B<-M>I<module> executes C<use> I<module> C<;> before executing your -program. You can use quotes to add extra code after the module name, -e.g., C<'-Mmodule qw(foo bar)'>. - -If the first character after the B<-M> or B<-m> is a dash (C<->) -then the 'use' is replaced with 'no'. - -A little builtin syntactic sugar means you can also say -B<-mmodule=foo,bar> or B<-Mmodule=foo,bar> as a shortcut for -C<'-Mmodule qw(foo bar)'>. This avoids the need to use quotes when -importing symbols. The actual code generated by B<-Mmodule=foo,bar> is -C<use module split(/,/,q{foo,bar})>. Note that the C<=> form -removes the distinction between B<-m> and B<-M>. - -=item B<-n> - -causes Perl to assume the following loop around your program, which -makes it iterate over filename arguments somewhat like B<sed -n> or -B<awk>: - - LINE: - while (<>) { - ... # your program goes here - } - -Note that the lines are not printed by default. See B<-p> to have -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. - -Here is an efficient way to delete all files older than a week: - - find . -mtime +7 -print | perl -nle unlink - -This is faster than using the B<-exec> switch of B<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 - -C<BEGIN> and C<END> blocks may be used to capture control before or after -the implicit program loop, just as in B<awk>. - -=item B<-p> - -causes Perl to assume the following loop around your program, which -makes it iterate over filename arguments somewhat like B<sed>: - - - LINE: - while (<>) { - ... # your program goes here - } continue { - print or die "-p destination: $!\n"; - } - -If a file named by an argument cannot be opened for some reason, Perl -warns you about it, and moves on to the next file. Note that the -lines are printed automatically. An error occurring during printing is -treated as fatal. To suppress printing use the B<-n> switch. A B<-p> -overrides a B<-n> switch. - -C<BEGIN> and C<END> blocks may be used to capture control before or after -the implicit loop, just as in B<awk>. - -=item B<-P> - -causes your program to be run through the C preprocessor before -compilation by Perl. Because both comments and B<cpp> directives begin -with the # character, you should avoid starting comments with any words -recognized by the C preprocessor such as C<"if">, C<"else">, or C<"define">. -Also, in some platforms the C preprocessor knows too much: it knows -about the C++ -style until-end-of-line comments starting with C<"//">. -This will cause problems with common Perl constructs like - - s/foo//; - -because after -P this will became illegal code - - s/foo - -The workaround is to use some other quoting separator than C<"/">, -like for example C<"!">: - - s!foo!!; - -=item B<-s> - -enables rudimentary switch parsing for switches on the command -line after the program name but before any filename arguments (or before -an argument of B<-->). This means you can have switches with two leading -dashes (B<--help>). Any switch found there is removed from @ARGV and sets the -corresponding variable in the Perl program. The following program -prints "1" if the program is invoked with a B<-xyz> switch, and "abc" -if it is invoked with B<-xyz=abc>. - - #!/usr/bin/perl -s - if ($xyz) { print "$xyz\n" } - -Do note that B<--help> creates the variable ${-help}, which is not compliant -with C<strict refs>. - -=item B<-S> - -makes Perl use the PATH environment variable to search for the -program (unless the name of the program contains directory separators). - -On some platforms, this also makes Perl append suffixes to the -filename while searching for it. For example, on Win32 platforms, -the ".bat" and ".cmd" suffixes are appended if a lookup for the -original name fails, and if the name does not already end in one -of those suffixes. If your Perl was compiled with DEBUGGING turned -on, using the -Dp switch to Perl shows how the search progresses. - -Typically this is used to emulate #! startup on platforms that -don't support #!. This example works on many platforms that -have a shell compatible with Bourne shell: - - #!/usr/bin/perl - eval 'exec /usr/bin/perl -wS $0 ${1+"$@"}' - if $running_under_some_shell; - -The system ignores the first line and feeds the program to F</bin/sh>, -which proceeds to try to execute the Perl program as a shell script. -The shell executes the second line as a normal shell command, and thus -starts up the Perl interpreter. On some systems $0 doesn't always -contain the full pathname, so the B<-S> tells Perl to search for the -program if necessary. After Perl locates the program, it parses the -lines and ignores them because the variable $running_under_some_shell -is never true. If the program will be interpreted by csh, you will need -to replace C<${1+"$@"}> with C<$*>, even though that doesn't understand -embedded spaces (and such) in the argument list. To start up sh rather -than csh, some systems may have to replace the #! line with a line -containing just a colon, which will be politely ignored by Perl. Other -systems can't control that, and need a totally devious construct that -will work under any of B<csh>, B<sh>, or Perl, such as the following: - - eval '(exit $?0)' && eval 'exec perl -wS $0 ${1+"$@"}' - & eval 'exec /usr/bin/perl -wS $0 $argv:q' - if $running_under_some_shell; - -If the filename supplied contains directory separators (i.e., is an -absolute or relative pathname), and if that file is not found, -platforms that append file extensions will do so and try to look -for the file with those extensions added, one by one. - -On DOS-like platforms, if the program does not contain directory -separators, it will first be searched for in the current directory -before being searched for on the PATH. On Unix platforms, the -program will be searched for strictly on the PATH. - -=item B<-T> - -forces "taint" checks to be turned on so you can test them. Ordinarily -these checks are done only when running setuid or setgid. It's a -good idea to turn them on explicitly for programs that run on behalf -of someone else whom you might not necessarily trust, such as CGI -programs or any internet servers you might write in Perl. See -L<perlsec> for details. For security reasons, this option must be -seen by Perl quite early; usually this means it must appear early -on the command line or in the #! line for systems which support -that construct. - -=item B<-u> - -This obsolete switch causes Perl to dump core after compiling your -program. You can then in theory take this core dump and turn it -into an executable file by using the B<undump> program (not supplied). -This speeds startup at the expense of some disk space (which you -can minimize by stripping the executable). (Still, a "hello world" -executable comes out to about 200K on my machine.) If you want to -execute a portion of your program before dumping, use the dump() -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> - -allows Perl to do unsafe operations. Currently the only "unsafe" -operations are the unlinking of directories while running as superuser, -and running setuid programs with fatal taint checks turned into -warnings. Note that the B<-w> switch (or the C<$^W> variable) must -be used along with this option to actually I<generate> the -taint-check warnings. - -=item B<-v> - -prints the version and patchlevel of your perl executable. - -=item B<-V> - -prints summary of the major perl configuration values and the current -values of @INC. - -=item B<-V:>I<name> - -Prints to STDOUT the value of the named configuration variable. -For example, - - $ perl -V:man.dir - -will provide strong clues about what your MANPATH variable should -be set to in order to access the Perl documentation. - -=item B<-w> - -prints warnings about dubious constructs, such as variable names -that are mentioned only once and scalar variables that are used -before being set, redefined subroutines, references to undefined -filehandles or filehandles opened read-only that you are attempting -to write on, values used as a number that doesn't look like numbers, -using an array as though it were a scalar, if your subroutines -recurse more than 100 deep, and innumerable other things. - -This switch really just enables the internal C<^$W> variable. You -can disable or promote into fatal errors specific warnings using -C<__WARN__> hooks, as described in L<perlvar> and L<perlfunc/warn>. -See also L<perldiag> and L<perltrap>. A new, fine-grained warning -facility is also available if you want to manipulate entire classes -of warnings; see L<warnings> or L<perllexwarn>. - -=item B<-W> - -Enables all warnings regardless of C<no warnings> or C<$^W>. -See L<perllexwarn>. - -=item B<-X> - -Disables all warnings regardless of C<use warnings> or C<$^W>. -See L<perllexwarn>. - -=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. -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 -C<__END__> if there is trailing garbage to be ignored (the program -can process any or all of the trailing garbage via the DATA filehandle -if desired). - -=back - -=head1 ENVIRONMENT - -=over 12 - -=item HOME - -Used if chdir has no argument. - -=item LOGDIR - -Used if chdir has no argument and HOME is not set. - -=item PATH - -Used in executing subprocesses, and in finding the program if B<-S> is -used. - -=item PERL5LIB - -A colon-separated list of directories in which to look for Perl library -files before looking in the standard library and the current -directory. Any architecture-specific directories under the specified -locations are automatically included if they exist. If PERL5LIB is not -defined, PERLLIB is used. - -When running taint checks (either because the program was running setuid -or setgid, or the B<-T> switch was used), neither variable is used. -The program should instead say: - - use lib "/my/directory"; - -=item PERL5OPT - -Command-line options (switches). Switches in this variable are taken -as if they were on every Perl command line. Only the B<-[DIMUdmw]> -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 -enabled, and any subsequent options ignored. - -=item PERLLIB - -A colon-separated list of directories in which to look for Perl library -files before looking in the standard library and the current directory. -If PERL5LIB is defined, PERLLIB is not used. - -=item PERL5DB - -The command used to load the debugger code. The default is: - - BEGIN { require 'perl5db.pl' } - -=item PERL5SHELL (specific to the Win32 port) - -May be set to an alternative shell that perl must use internally for -executing "backtick" commands or system(). Default is C<cmd.exe /x/c> -on WindowsNT and C<command.com /c> on Windows95. The value is considered -to be space-separated. Precede any character that needs to be protected -(like a space or backslash) with a backslash. - -Note that Perl doesn't use COMSPEC for this purpose because -COMSPEC has a high degree of variability among users, leading to -portability concerns. Besides, perl can use a shell that may not be -fit for interactive use, and setting COMSPEC to such a shell may -interfere with the proper functioning of other programs (which usually -look in COMSPEC to find a shell fit for interactive use). - -=item PERL_DEBUG_MSTATS - -Relevant only if perl is compiled with the malloc included with the perl -distribution (that is, if C<perl -V:d_mymalloc> is 'define'). -If set, this causes memory statistics to be dumped after execution. If set -to an integer greater than one, also causes memory statistics to be dumped -after compilation. - -=item PERL_DESTRUCT_LEVEL - -Relevant only if your perl executable was built with B<-DDEBUGGING>, -this controls the behavior of global destruction of objects and other -references. - -=item PERL_ROOT (specific to the VMS port) - -A translation concealed rooted logical name that contains perl and the -logical device for the @INC path on VMS only. Other logical names that -affect perl on VMS include PERLSHR, PERL_ENV_TABLES, and -SYS$TIMEZONE_DIFFERENTIAL but are optional and discussed further in -L<perlvms> and in F<README.vms> in the Perl source distribution. - -=item SYS$LOGIN (specific to the VMS port) - -Used if chdir has no argument and HOME and LOGDIR are not set. - -=back - -Perl also has environment variables that control how Perl handles data -specific to particular natural languages. See L<perllocale>. - -Apart from these, Perl uses no other environment variables, except -to make them available to the program being executed, and to child -processes. However, programs running setuid would do well to execute -the following lines before doing anything else, just to keep people -honest: - - $ENV{PATH} = '/bin:/usr/bin'; # or whatever you need - $ENV{SHELL} = '/bin/sh' if exists $ENV{SHELL}; - delete @ENV{qw(IFS CDPATH ENV BASH_ENV)}; |
