=head1 SYNOPSIS
-B<perl> S<[ B<-CsTtuUWX> ]>
+B<perl> S<[ B<-sTtuUWX> ]>
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<-cw> ] [ B<-d>[B<t>][:I<debugger>] ] [ B<-D>[I<number/list>] ]>
+ 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<-A>[I<module>][=I<assertions>] ]>
+ S<[ B<-C [I<number/list>] >]>
S<[ B<-P> ]>
S<[ B<-S> ]>
S<[ B<-x>[I<dir>] ]>
eval 'exec perl -wS $0 ${1+"$@"}'
if $running_under_some_shell;
-to let Perl see the B<-p> switch.
+to let Perl see the B<-p> switch.
A similar trick involves the B<env> program, if you have it.
=item MS-DOS
Create a batch file to run your program, and codify it in
-C<ALTERNATIVE_SHEBANG> (see the F<dosish.h> file in the source
+C<ALTERNATE_SHEBANG> (see the F<dosish.h> file in the source
distribution for more information).
=item Win95/NT
=item Macintosh
-A Macintosh perl program will have the appropriate Creator and
-Type, so that double-clicking them will invoke the perl application.
+Under "Classic" MacOS, a perl program will have the appropriate Creator and
+Type, so that double-clicking them will invoke the MacPerl application.
+Under Mac OS X, clickable apps can be made from any C<#!> script using Wil
+Sanchez' DropScript utility: http://www.wsanchez.net/software/ .
=item VMS
one-liners (see B<-e> below).
On some systems, you may have to change single-quotes to double ones,
-which you must I<not> do on Unix or Plan9 systems. You might also
+which you must I<not> do on Unix or Plan 9 systems. You might also
have to change a single % to a %%.
For example:
=over 5
-=item B<-0>[I<digits>]
+=item B<-0>[I<octal/hexadecimal>]
-specifies the input record separator (C<$/>) 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:
+specifies the input record separator (C<$/>) as an octal or
+hexadecimal number. If there are no digits, the null character is the
+separator. Other switches may precede or follow the digits. For
+example, if you have a version of B<find> which can print filenames
+terminated by the null character, you can say this:
find . -name '*.orig' -print0 | perl -n0e unlink
The special value 00 will cause Perl to slurp files in paragraph mode.
The value 0777 will cause Perl to slurp files whole because there is no
-legal character with that value.
+legal byte with that value.
+
+If you want to specify any Unicode character, use the hexadecimal
+format: C<-0xHHH...>, where the C<H> are valid hexadecimal digits.
+(This means that you cannot use the C<-x> with a directory name that
+consists of hexadecimal digits.)
+
+=item B<-A[I<module>][=I<assertions>]>
+
+Activates the assertions given after the equal sign as a comma-separated
+list of assertion names or regular expressions. If no assertion name
+is given, activates all assertions.
+
+The module L<assertions::activate> is used by default to activate the
+selected assertions. An alternate module may be specified including
+its name between the switch and the equal sign.
+
+See L<assertions> and L<assertions::activate>.
=item B<-a>
An alternate delimiter may be specified using B<-F>.
-=item B<-C>
-
-enables Perl to use the native wide character APIs on the target system.
-The magic variable C<${^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 [I<number/list>]>
+
+The C<-C> flag controls some Unicode 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
+are as follows; listing the letters is equal to summing the numbers.
+
+ I 1 STDIN is assumed to be in UTF-8
+ O 2 STDOUT will be in UTF-8
+ E 4 STDERR will be in UTF-8
+ S 7 I + O + E
+ i 8 UTF-8 is the default PerlIO layer for input streams
+ o 16 UTF-8 is the default PerlIO layer for output streams
+ D 24 i + o
+ A 32 the @ARGV elements are expected to be strings encoded
+ 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 decreasing precedence) -- if the variables indicate
+ UTF-8, then the selected "IOEioA" are in effect
+
+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
+nor toggling.
+
+The C<io> options mean that any subsequent open() (or similar I/O
+operations) will have the C<:utf8> PerlIO layer implicitly applied
+to them, in other words, UTF-8 is expected from any input stream,
+and UTF-8 is produced to any output stream. This is just the default,
+with explicit layers in open() and with binmode() one can manipulate
+streams as usual.
+
+C<-C> on its own (not followed by any number or option list), or the
+empty string C<""> for the C<PERL_UNICODE> environment variable, has the
+same effect as C<-CSDL>. In other words, the standard I/O handles and
+the default C<open()> layer are UTF-8-fied B<but> only if the locale
+environment variables indicate a UTF-8 locale. This behaviour follows
+the I<implicit> (and problematic) UTF-8 behaviour of Perl 5.8.0.
+
+You can use C<-C0> (or C<"0"> for C<PERL_UNICODE>) to explicitly
+disable all the above Unicode features.
+
+The read-only magic variable C<${^UNICODE}> reflects the numeric value
+of this setting. This is variable is set during Perl startup and is
+thereafter read-only. If you want runtime effects, use the three-arg
+open() (see L<perlfunc/open>), the two-arg binmode() (see L<perlfunc/binmode>),
+and the C<open> pragma (see L<open>).
+
+(In Perls earlier than 5.8.1 the C<-C> switch was a Win32-only switch
+that enabled the use of Unicode-aware "wide system call" Win32 APIs.
+This feature was practically unused, however, and the command line
+switch was therefore "recycled".)
=item B<-c>
=item B<-d>
+=item B<-dt>
+
runs the program under the Perl debugger. See L<perldebug>.
+If B<t> is specified, it indicates to the debugger that threads
+will be used in the code being debugged.
=item B<-d:>I<foo[=bar,baz]>
+=item B<-dt:>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.
+If B<t> is specified, it indicates to the debugger that threads
+will be used in the code being debugged.
See L<perldebug>.
=item B<-D>I<letters>
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>.
+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
- 2 s Stack snapshots
+ 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 preprocessor command for -P, source file input state
+ 64 P Print profiling info, 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)
+ 4096 (Obsolete, previously used for LEAKTEST)
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
+ 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
All these flags require B<-DDEBUGGING> when you compile the Perl
-executable. See the F<INSTALL> file in the Perl source distribution
+executable (but see L<Devel::Peek>, L<re> 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.
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
+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
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>
+
+Disable executing F<$Config{siteperl}/sitecustomize.pl> at
+startup.
+
+Perl can be built so that it by default will try to execute
+F<$Config{siteperl}/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<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.
+put in single quotes. You can't use literal whitespace in the pattern.
=item B<-h>
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'
+ $ 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'
+ $ 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'*' -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'
+ $ 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
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...
+ $ perl -p -i'/some/file/path/*' -e 1 file1 file2 file3...
or
- $ perl -p -i '.orig' -e 1 file1 file2 file3...
+ $ 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
$ perl -pi~ -e 's/foo/bar/' file1 file2 file3...
+Note that because B<-i> renames or deletes the original file before
+creating a new file of the same name, UNIX-style soft and hard links will
+not be preserved.
+
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
C<use module split(/,/,q{foo,bar})>. 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<Foo::import()> itself is set up to do a version check, which
+could happen for example if Foo inherits from Exporter.)
+
=item B<-n>
causes Perl to assume the following loop around your program, which
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:
+Here is an efficient way to delete all files that haven't been modified for
+at least 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
+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 B<awk>.
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 .
+inside Perl strings, regular expressions, and here-docs .
=item *
if ($xyz) { print "$xyz\n" }
Do note that B<--help> creates the variable ${-help}, which is not compliant
-with C<strict refs>.
+with C<strict refs>. 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>
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:
+Typically this is used to emulate #! startup on platforms that don't
+support #!. Its also convenient when debugging a script that uses #!,
+and is thus normally found by the shell's $PATH search mechanism.
+
+This example works on many platforms that have a shell compatible with
+Bourne shell:
#!/usr/bin/perl
eval 'exec /usr/bin/perl -wS $0 ${1+"$@"}'
prints summary of the major perl configuration values and the current
values of @INC.
-=item B<-V:>I<name>
+=item B<-V:>I<configvar>
+
+Prints to STDOUT the value of the named configuration variable(s),
+with multiples when your configvar argument looks like a regex (has
+non-letters). For example:
+
+ $ perl -V:libc
+ libc='/lib/libc-2.2.4.so';
+ $ perl -V:lib.
+ libs='-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc';
+ libc='/lib/libc-2.2.4.so';
+ $ perl -V:lib.*
+ libpth='/usr/local/lib /lib /usr/lib';
+ libs='-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc';
+ lib_ext='.a';
+ libc='/lib/libc-2.2.4.so';
+ libperl='libperl.a';
+ ....
+
+Additionally, extra colons can be used to control formatting. A
+trailing colon suppresses the linefeed and terminator ';', allowing
+you to embed queries into shell commands. (mnemonic: PATH separator
+':'.)
+
+ $ echo "compression-vars: " `perl -V:z.*: ` " are here !"
+ compression-vars: zcat='' zip='zip' are here !
+
+A leading colon removes the 'name=' part of the response, this allows
+you to map to the name you need. (mnemonic: empty label)
-Prints to STDOUT the value of the named configuration variable.
-For example,
+ $ echo "goodvfork="`./perl -Ilib -V::usevfork`
+ goodvfork=false;
- $ perl -V:man.dir
+Leading and trailing colons can be used together if you need
+positional parameter values without the names. Note that in the case
+below, the PERL_API params are returned in alphabetical order.
-will provide strong clues about what your MANPATH variable should
-be set to in order to access the Perl documentation.
+ $ echo building_on `perl -V::osname: -V::PERL_API_.*:` now
+ building_on 'linux' '5' '1' '9' now
=item B<-w>
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.
-This switch really just enables the internal C<^$W> variable. You
+This switch really just enables the internal C<$^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
Disables all warnings regardless of C<use warnings> or C<$^W>.
See L<perllexwarn>.
+=item B<-x>
+
=item B<-x> I<directory>
tells Perl that the program is embedded in a larger chunk of unrelated
=item PERL5LIB
-A colon-separated list of directories in which to look for Perl library
+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.
+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<perl -V:path_sep>).
When running taint checks (either because the program was running setuid
or setgid, or the B<-T> switch was used), neither variable is used.
=item PERL5OPT
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
+
+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.
+
+It is conventional to start layer names with a colon e.g. C<:perlio> to
+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>.
+
+The list becomes the default for I<all> perl's IO. Consequently only built-in
+layers can appear in this list, as external layers (such as :encoding()) need
+IO in order to load them!. See L<"open pragma"|open> for how to add external
+encodings as defaults.
+
+The layers that it makes sense to include in the PERLIO environment
+variable are briefly summarised below. For more details see L<PerlIO>.
+
+=over 8
+
+=item :bytes
+
+A pseudolayer that turns I<off> 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
+
+A layer which does CRLF to "\n" translation distinguishing "text" and
+"binary" files in the manner of MS-DOS and similar operating systems.
+(It currently does I<not> mimic MS-DOS as far as treating of Control-Z
+as being an end-of-file marker.)
+
+=item :mmap
+
+A layer which implements "reading" of files by using C<mmap()> to
+make (whole) file appear in the process's address space, and then
+using that as PerlIO's "buffer".
+
+=item :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
+
+An experimental pseudolayer that removes the topmost layer.
+Use with the same care as is reserved for nitroglycerin.
+
+=item :raw
+
+A pseudolayer that manipulates other layers. Applying the C<:raw>
+layer is equivalent to calling C<binmode($fh)>. It makes the stream
+pass each byte as-is without any translation. In particular CRLF
+translation, and/or :utf8 intuited from locale are disabled.
+
+Unlike in the earlier versions of Perl C<:raw> is I<not>
+just the inverse of C<:crlf> - other layers which would affect the
+binary nature of the stream are also removed or disabled.
+
+=item :stdio
+
+This layer provides PerlIO interface by wrapping system's ANSI C "stdio"
+library calls. The layer provides both buffering and IO.
+Note that C<:stdio> layer does I<not> do CRLF translation even if that
+is platforms normal behaviour. You will need a C<:crlf> layer above it
+to do that.
+
+=item :unix
+
+Low level layer which calls C<read>, C<write> and C<lseek> etc.
+
+=item :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
+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.)
+
+=item :win32
+
+On Win32 platforms this I<experimental> layer uses native "handle" IO
+rather than unix-like numeric file descriptor layer. Known to be
+buggy in this release.
+
+=back
+
+On all platforms the default set of layers should give acceptable results.
+
+For UNIX platforms that will equivalent of "unix perlio" or "stdio".
+Configure is setup to prefer "stdio" implementation if system's library
+provides for fast access to the buffer, otherwise it uses the "unix perlio"
+implementation.
+
+On Win32 the default in this release is "unix crlf". Win32's "stdio"
+has a number of bugs/mis-features for perl IO which are somewhat
+C compiler vendor/version dependent. Using our own C<crlf> layer as
+the buffer avoids those issues and makes things more uniform.
+The C<crlf> layer provides CRLF to/from "\n" conversion as well as
+buffering.
+
+This release uses C<unix> as the bottom layer on Win32 and so still uses C
+compiler's numeric file descriptor routines. There is an experimental native
+C<win32> layer which is expected to be enhanced and should eventually be
+the default under Win32.
+
+=item PERLIO_DEBUG
+
+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
+are UNIX:
+
+ PERLIO_DEBUG=/dev/tty perl script ...
+
+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
-A colon-separated list of directories in which to look for Perl library
+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.
BEGIN { require 'perl5db.pl' }
+=item PERL5DB_THREADED
+
+If set to a true value, indicates to the debugger that the code being
+debugged uses threads.
+
=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>
+executing "backtick" commands or system(). Default is C<cmd.exe /x/d/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.
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)
+
+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
+for its emulation of Windows sockets as real filehandles. However, this may
+cause problems if you have a firewall such as McAfee Guardian which requires
+all applications to use its LSP which is not IFS-compatible, because clearly
+Perl will normally avoid using such an LSP.
+Setting this environment variable to 1 means that Perl will simply use the
+first suitable LSP enumerated in the catalog, which keeps McAfee Guardian
+happy (and in that particular case Perl still works too because McAfee
+Guardian's LSP actually plays some other games which allow applications
+requiring IFS compatibility to work).
+
=item PERL_DEBUG_MSTATS
Relevant only if perl is compiled with the malloc included with the perl
this controls the behavior of global destruction of objects and other
references. See L<perlhack/PERL_DESTRUCT_LEVEL> for more information.
+=item PERL_DL_NONLAZY
+
+Set to one to have perl resolve B<all> undefined symbols when it loads
+a dynamic library. The default behaviour is to resolve symbols when
+they are used. Setting this variable is useful during testing of
+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
If using the C<encoding> pragma without an explicit encoding name, the
PERL_ENCODING environment variable is consulted for an encoding name.
+=item PERL_HASH_SEED
+
+(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.
+
+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
+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
+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
+code. By manually setting a seed this protection may be partially or
+completely lost.
+
+See L<perlsec/"Algorithmic Complexity Attacks"> and
+L</PERL_HASH_SEED_DEBUG> for more information.
+
+=item PERL_HASH_SEED_DEBUG
+
+(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
+L</PERL_HASH_SEED> is intended to aid in debugging nondeterministic
+behavior caused by hash randomization.
+
+B<Note that the hash seed is sensitive information>: by knowing it one
+can craft a denial-of-service attack against Perl code, even remotely,
+see L<perlsec/"Algorithmic Complexity Attacks"> for more information.
+B<Do not disclose the hash seed> to people who don't need to know it.
+See also hash_seed() of L<Hash::Util>.
+
=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$TIMEZONE_DIFFERENTIAL but are optional and discussed further in
+affect perl on VMS include PERLSHR, PERL_ENV_TABLES, and
+SYS$TIMEZONE_DIFFERENTIAL but are optional and discussed further in
L<perlvms> and in F<README.vms> in the Perl source distribution.
+=item PERL_SIGNALS
+
+In Perls 5.8.1 and later. If set to C<unsafe> the pre-Perl-5.8.0
+signals behaviour (immediate but unsafe) is restored. If set to
+C<safe> the safe (or deferred) signals are used.
+See L<perlipc/"Deferred Signals (Safe Signals)">.
+
+=item PERL_UNICODE
+
+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
+"enable Unicode" (whatever that would mean). You can use C<"0"> to
+"disable Unicode", though (or alternatively unset PERL_UNICODE in
+your shell before starting Perl). See the description of the C<-C>
+switch for more information.
+
=item SYS$LOGIN (specific to the VMS port)
Used if chdir has no argument and HOME and LOGDIR are not set.
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