X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlrun.pod;h=a72c2c01f6a78d80df5c2348f92b9e4e0bbbf851;hb=584420f022db57225e9644b9c6668ff9f567984a;hp=029b09bbba194289427e4a43b769568d5ea1305d;hpb=fa11829f4b6d56533794dd127f3d1068d9593670;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlrun.pod b/pod/perlrun.pod index 029b09b..a72c2c0 100644 --- a/pod/perlrun.pod +++ b/pod/perlrun.pod @@ -8,14 +8,13 @@ B S<[ B<-sTtuUWX> ]> S<[ B<-hv> ] [ B<-V>[:I] ]> S<[ B<-cw> ] [ B<-d>[B][:I] ] [ B<-D>[I] ]> S<[ B<-pna> ] [ B<-F>I ] [ B<-l>[I] ] [ B<-0>[I] ]> - S<[ B<-I>I ] [ B<-m>[B<->]I ] [ B<-M>[B<->]I<'module...'> ]> + S<[ B<-I>I ] [ B<-m>[B<->]I ] [ B<-M>[B<->]I<'module...'> ] [ B<-f> ]> + S<[ B<-C [I] >]> S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I] ]> S<[ B<-i>[I] ]> - S<[ B<-e> I<'command'> ] [ B<--> ] [ I ] [ I ]...> - S<[ B<-A [I] >]> - S<[ B<-C [I] >]> + S<[ B<-eE> I<'command'> ] [ B<--> ] [ I ] [ I ]...> =head1 DESCRIPTION @@ -30,7 +29,7 @@ places: =item 1. -Specified line by line via B<-e> switches on the command line. +Specified line by line via B<-e> or B<-E> switches on the command line. =item 2. @@ -110,6 +109,7 @@ runs off the end without hitting an exit() or die() operator, an implicit C is provided to indicate successful completion. =head2 #! and quoting on non-Unix systems +X X<#!> Unix's #! technique can be simulated on other systems: @@ -141,8 +141,10 @@ 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. +Under "Classic" MacOS, a perl program will have the appropriate Creator and +Type, so that double-clicking them will invoke the MacPerl application. +Under Mac OS X, clickable apps can be made from any C<#!> script using Wil +Sanchez' DropScript utility: http://www.wsanchez.net/software/ . =item VMS @@ -204,6 +206,7 @@ characters as control characters. There is no general solution to all of this. It's just a mess. =head2 Location of Perl +X 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 @@ -225,6 +228,7 @@ like this at the top of your program: use 5.005_54; =head2 Command Switches +X X As with all standard commands, a single-character switch may be clustered with the following switch, if any. @@ -236,6 +240,7 @@ Switches include: =over 5 =item B<-0>[I] +X<-0> X<$/> specifies the input record separator (C<$/>) as an octal or hexadecimal number. If there are no digits, the null character is the @@ -254,13 +259,8 @@ format: C<-0xHHH...>, where the C are valid hexadecimal digits. (This means that you cannot use the C<-x> with a directory name that consists of hexadecimal digits.) -=item B<-A [I]> - -Activates the assertions given after the switch as a comma-separated -list of assertion names. If no assertion name is given, activates all -assertions. See L. - =item B<-a> +X<-a> X 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 @@ -278,6 +278,7 @@ is equivalent to An alternate delimiter may be specified using B<-F>. =item B<-C [I]> +X<-C> The C<-C> flag controls some Unicode of the Perl Unicode features. @@ -299,6 +300,15 @@ are as follows; listing the letters is equal to summing the numbers. variables (the LC_ALL, LC_TYPE, 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 code in + debugging mode. + +=for documenting_the_underdocumented +perl.h gives W/128 as PERL_UNICODE_WIDESYSCALLS "/* for Sarathy */" + +=for todo +perltodo mentions Unicode in %ENV and filenames. I guess that these will be +options e and f (or F). For example, C<-COE> and C<-C6> will both turn on UTF-8-ness on both STDOUT and STDERR. Repeating letters is just redundant, not cumulative @@ -333,14 +343,16 @@ This feature was practically unused, however, and the command line switch was therefore "recycled".) =item B<-c> +X<-c> causes Perl to check the syntax of the program and then exit without -executing it. Actually, it I execute C, C, and -C blocks, because these are considered as occurring outside the -execution of your program. C and C blocks, however, will -be skipped. +executing it. Actually, it I execute C, C, +C, and C blocks, because these are considered as occurring +outside the execution of your program. C and C blocks, +however, will be skipped. =item B<-d> +X<-d> X<-dt> =item B<-dt> @@ -349,6 +361,7 @@ If B is specified, it indicates to the debugger that threads will be used in the code being debugged. =item B<-d:>I +X<-d> X<-dt> =item B<-dt:>I @@ -363,6 +376,7 @@ will be used in the code being debugged. See L. =item B<-D>I +X<-D> X X<-DDEBUGGING> =item B<-D>I @@ -411,7 +425,7 @@ as it executes, the way that C provides for shell scripts, you can't use Perl's B<-D> switch. Instead do this # If you have "env" utility - env=PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program + env PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program # Bourne shell syntax $ PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program @@ -422,23 +436,44 @@ you can't use Perl's B<-D> switch. Instead do this See L for details and variations. =item B<-e> I +X<-e> 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<-E> I +X<-E> + +behaves just like B<-e>, except that it implicitly enables all +optional features (in the main compilation unit). See L. + +=item B<-f> +X<-f> + +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. + =item B<-F>I +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. +put in single quotes. You can't use literal whitespace in the pattern. =item B<-h> +X<-h> prints a summary of the options. =item B<-i>[I] +X<-i> X specifies that files processed by the CE> construct are to be edited in-place. It does this by renaming the input file, opening the @@ -550,6 +585,7 @@ files are given on the command line. In this case, no backup is made proceeds from STDIN to STDOUT as might be expected. =item B<-I>I +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 @@ -557,6 +593,7 @@ include files. The C preprocessor is invoked with B<-P>; by default it searches /usr/include and /usr/lib/perl. =item B<-l>[I] +X<-l> X<$/> X<$\> enables automatic line-ending processing. It has two separate effects. First, it automatically chomps C<$/> (the input record @@ -577,6 +614,7 @@ separator if the B<-l> switch is followed by a B<-0> switch: This sets C<$\> to newline and then sets C<$/> to the null character. =item B<-m>[B<->]I +X<-m> X<-M> =item B<-M>[B<->]I @@ -601,7 +639,12 @@ importing symbols. The actual code generated by B<-Mmodule=foo,bar> is C. Note that the C<=> form removes the distinction between B<-m> and B<-M>. +A consequence of this is that B<-MFoo=number> never does a version check +(unless C itself is set up to do a version check, which +could happen for example if Foo inherits from Exporter.) + =item B<-n> +X<-n> causes Perl to assume the following loop around your program, which makes it iterate over filename arguments somewhat like B or @@ -630,6 +673,7 @@ C and C blocks may be used to capture control before or after the implicit program loop, just as in B. =item B<-p> +X<-p> causes Perl to assume the following loop around your program, which makes it iterate over filename arguments somewhat like B: @@ -652,6 +696,7 @@ C and C blocks may be used to capture control before or after the implicit loop, just as in B. =item B<-P> +X<-P> B @@ -717,11 +762,11 @@ The C<-x> does not work with C<-P>. =back =item B<-s> +X<-s> enables rudimentary switch parsing for switches on the command line after the program name but before any filename arguments (or before -an argument of B<-->). This means you can have switches with two leading -dashes (B<--help>). Any switch found there is removed from @ARGV and sets the +an argument of B<-->). Any switch found there is removed from @ARGV and sets the corresponding variable in the Perl program. The following program prints "1" if the program is invoked with a B<-xyz> switch, and "abc" if it is invoked with B<-xyz=abc>. @@ -729,10 +774,12 @@ if it is invoked with B<-xyz=abc>. #!/usr/bin/perl -s if ($xyz) { print "$xyz\n" } -Do note that B<--help> creates the variable ${-help}, which is not compliant -with C. +Do note that a switch like B<--help> creates the variable ${-help}, which is not compliant +with C. Also, when using this option on a script with +warnings enabled you may get a lot of spurious "used only once" warnings. =item B<-S> +X<-S> makes Perl use the PATH environment variable to search for the program (unless the name of the program contains directory separators). @@ -785,6 +832,7 @@ before being searched for on the PATH. On Unix platforms, the program will be searched for strictly on the PATH. =item B<-t> +X<-t> Like B<-T>, but taint checks will issue warnings rather than fatal errors. These warnings can be controlled normally with C. =item B<-T> +X<-T> forces "taint" checks to be turned on so you can test them. Ordinarily these checks are done only when running setuid or setgid. It's a @@ -808,6 +857,7 @@ on the command line or in the #! line for systems which support that construct. =item B<-u> +X<-u> This obsolete switch causes Perl to dump core after compiling your program. You can then in theory take this core dump and turn it @@ -824,19 +874,22 @@ generator backends to the compiler. See L and L for details. =item B<-U> +X<-U> allows Perl to do unsafe operations. Currently the only "unsafe" -operations are the unlinking of directories while running as superuser, -and running setuid programs with fatal taint checks turned into -warnings. Note that the B<-w> switch (or the C<$^W> variable) must -be used along with this option to actually I the -taint-check warnings. +operations are attempting to unlink 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<$^W> variable) +must be used along with this option to actually I the +taint-check warnings. =item B<-v> +X<-v> prints the version and patchlevel of your perl executable. =item B<-V> +X<-V> prints summary of the major perl configuration values and the current values of @INC. @@ -882,12 +935,13 @@ below, the PERL_API params are returned in alphabetical order. building_on 'linux' '5' '1' '9' now =item B<-w> +X<-w> prints warnings about dubious constructs, such as variable names that are mentioned only once and scalar variables that are used before being set, redefined subroutines, references to undefined filehandles or filehandles opened read-only that you are attempting -to write on, values used as a number that doesn't look like numbers, +to write on, values used as a number that don't look like numbers, using an array as though it were a scalar, if your subroutines recurse more than 100 deep, and innumerable other things. @@ -899,16 +953,19 @@ facility is also available if you want to manipulate entire classes of warnings; see L or L. =item B<-W> +X<-W> Enables all warnings regardless of C or C<$^W>. See L. =item B<-X> +X<-X> Disables all warnings regardless of C or C<$^W>. See L. =item B<-x> +X<-x> =item B<-x> I @@ -926,48 +983,58 @@ if desired). =back =head1 ENVIRONMENT +X =over 12 =item HOME +X Used if chdir has no argument. =item LOGDIR +X Used if chdir has no argument and HOME is not set. =item PATH +X Used in executing subprocesses, and in finding the program if B<-S> is used. =item PERL5LIB +X A 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. Directories are separated (like in PATH) by -a colon on unixish platforms and by a semicolon on Windows (the proper -path separator being given by the command C). +locations are automatically included if they exist (this lookup +being done at interpreter startup time.) + +If PERL5LIB is not defined, PERLLIB is used. Directories are separated +(like in PATH) by a colon on unixish platforms and by a semicolon on +Windows (the proper path separator being given by the command C). 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: +or setgid, or the B<-T> or B<-t> switch was specified), neither variable +is used. The program should instead say: use lib "/my/directory"; =item PERL5OPT +X Command-line options (switches). Switches in this variable are taken -as if they were on every Perl command line. Only the B<-[DIMUdmtw]> +as if they were on every Perl command line. Only the B<-[CDIMUdmtwA]> 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 PERLIO +X A space (or colon) separated list of PerlIO layers. If perl is built to use PerlIO system for IO (the default) these layers effect perl's IO. @@ -977,7 +1044,9 @@ emphasise their similarity to variable "attributes". But the code that parses layer specification strings (which is also used to decode the PERLIO environment variable) treats the colon as a separator. -An unset or empty PERLIO is equivalent to C<:stdio>. +An unset or empty PERLIO is equivalent to the default set of layers for +your platform, for example C<:unix:perlio> on UNIX-like systems +and C<:unix:crlf> on Windows and other DOS-like systems. The list becomes the default for I perl's IO. Consequently only built-in layers can appear in this list, as external layers (such as :encoding()) need @@ -990,12 +1059,14 @@ variable are briefly summarised below. For more details see L. =over 8 =item :bytes +X<:bytes> A pseudolayer that turns I the C<:utf8> flag for the layer below. Unlikely to be useful on its own in the global PERLIO environment variable. You perhaps were thinking of C<:crlf:bytes> or C<:perlio:bytes>. =item :crlf +X<:crlf> A layer which does CRLF to "\n" translation distinguishing "text" and "binary" files in the manner of MS-DOS and similar operating systems. @@ -1003,23 +1074,27 @@ A layer which does CRLF to "\n" translation distinguishing "text" and as being an end-of-file marker.) =item :mmap +X<:mmap> A layer which implements "reading" of files by using C to make (whole) file appear in the process's address space, and then using that as PerlIO's "buffer". =item :perlio +X<:perlio> This is a re-implementation of "stdio-like" buffering written as a PerlIO "layer". As such it will call whatever layer is below it for its operations (typically C<:unix>). =item :pop +X<:pop> An experimental pseudolayer that removes the topmost layer. Use with the same care as is reserved for nitroglycerin. =item :raw +X<:raw> A pseudolayer that manipulates other layers. Applying the C<:raw> layer is equivalent to calling C. It makes the stream @@ -1031,6 +1106,7 @@ just the inverse of C<:crlf> - other layers which would affect the binary nature of the stream are also removed or disabled. =item :stdio +X<:stdio> This layer provides PerlIO interface by wrapping system's ANSI C "stdio" library calls. The layer provides both buffering and IO. @@ -1039,10 +1115,12 @@ is platforms normal behaviour. You will need a C<:crlf> layer above it to do that. =item :unix +X<:unix> Low level layer which calls C, C and C etc. =item :utf8 +X<:utf8> 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 @@ -1051,6 +1129,7 @@ variable to make UTF-8 the default. (To turn off that behaviour use C<:bytes> layer.) =item :win32 +X<:win32> On Win32 platforms this I layer uses native "handle" IO rather than unix-like numeric file descriptor layer. Known to be @@ -1078,6 +1157,7 @@ C layer which is expected to be enhanced and should eventually be the default under Win32. =item PERLIO_DEBUG +X If set to the name of a file or device then certain operations of PerlIO sub-system will be logged to that file (opened as append). Typical uses @@ -1090,25 +1170,31 @@ and Win32 approximate equivalent: set PERLIO_DEBUG=CON perl script ... +This functionality is disabled for setuid scripts and for scripts run +with B<-T>. =item PERLLIB +X A 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 +X The command used to load the debugger code. The default is: BEGIN { require 'perl5db.pl' } =item PERL5DB_THREADED +X If set to a true value, indicates to the debugger that the code being debugged uses threads. =item PERL5SHELL (specific to the Win32 port) +X May be set to an alternative shell that perl must use internally for executing "backtick" commands or system(). Default is C @@ -1124,6 +1210,7 @@ interfere with the proper functioning of other programs (which usually look in COMSPEC to find a shell fit for interactive use). =item PERL_ALLOW_NON_IFS_LSP (specific to the Win32 port) +X Set to 1 to allow the use of non-IFS compatible LSP's. Perl normally searches for an IFS-compatible LSP because this is required @@ -1138,6 +1225,7 @@ Guardian's LSP actually plays some other games which allow applications requiring IFS compatibility to work). =item PERL_DEBUG_MSTATS +X Relevant only if perl is compiled with the malloc included with the perl distribution (that is, if C is 'define'). @@ -1146,12 +1234,14 @@ to an integer greater than one, also causes memory statistics to be dumped after compilation. =item PERL_DESTRUCT_LEVEL +X Relevant only if your perl executable was built with B<-DDEBUGGING>, this controls the behavior of global destruction of objects and other references. See L for more information. =item PERL_DL_NONLAZY +X Set to one to have perl resolve B undefined symbols when it loads a dynamic library. The default behaviour is to resolve symbols when @@ -1160,11 +1250,13 @@ extensions as it ensures that you get an error on misspelled function names even if the test suite doesn't call it. =item PERL_ENCODING +X If using the C pragma without an explicit encoding name, the PERL_ENCODING environment variable is consulted for an encoding name. =item PERL_HASH_SEED +X (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 @@ -1190,6 +1282,7 @@ See L and L for more information. =item PERL_HASH_SEED_DEBUG +X (Since Perl 5.8.1.) Set to one to display (to STDERR) the value of the hash seed at the beginning of execution. This, combined with @@ -1203,6 +1296,7 @@ B to people who don't need to know it. See also hash_seed() of L. =item PERL_ROOT (specific to the VMS port) +X A translation concealed rooted logical name that contains perl and the logical device for the @INC path on VMS only. Other logical names that @@ -1211,13 +1305,15 @@ SYS$TIMEZONE_DIFFERENTIAL but are optional and discussed further in L and in F in the Perl source distribution. =item PERL_SIGNALS +X In Perls 5.8.1 and later. If set to C the pre-Perl-5.8.0 signals behaviour (immediate but unsafe) is restored. If set to C the safe (or deferred) signals are used. -See L. +See L. =item PERL_UNICODE +X Equivalent to the B<-C> command-line switch. Note that this is not a boolean variable-- setting this to C<"1"> is not the right way to @@ -1227,6 +1323,7 @@ your shell before starting Perl). See the description of the C<-C> switch for more information. =item SYS$LOGIN (specific to the VMS port) +X Used if chdir has no argument and HOME and LOGDIR are not set.