X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlvar.pod;h=3b9ed060afc1adb05a01f7fa8bf95bf04189a65a;hb=71f882da828ecd892a162839f27e4625d69023fb;hp=ae7261765b753093d0744ca1fb81dd069b2f036b;hpb=68fb0eb7ecdd3258dde75aba3e98109bd2bcc6c3;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlvar.pod b/pod/perlvar.pod index ae72617..3b9ed06 100644 --- a/pod/perlvar.pod +++ b/pod/perlvar.pod @@ -769,6 +769,12 @@ The process number of the Perl running this script. You should consider this variable read-only, although it will be altered across fork() calls. (Mnemonic: same as shells.) +Note for Linux users: on Linux, the C functions C and +C return different values from different threads. In order to +be portable, this behavior is not reflected by C<$$>, whose value remains +consistent across threads. If you want to call the underlying C, +you may use the CPAN module C. + =item $REAL_USER_ID =item $UID @@ -863,6 +869,10 @@ from the ps(1) output. For example, setting C<$0> to C<"foobar"> will result in C<"perl: foobar (perl)">. This is an operating system feature. +In multithreaded scripts Perl coordinates the threads so that any +thread may modify its copy of the C<$0> and the change becomes visible +to ps(1) (assuming the operating system plays along). + =item $[ The index of the first element in an array, and of the first character @@ -873,8 +883,14 @@ subscripting and when evaluating the index() and substr() functions. As of release 5 of Perl, assignment to C<$[> is treated as a compiler directive, and cannot influence the behavior of any other file. +(That's why you can only assign compile-time constants to it.) Its use is highly discouraged. +Note that, unlike other compile-time directives (such as L), +assignment to $[ can be seen from outer lexical scopes in the same file. +However, you can use local() on it to strictly bound its value to a +lexical block. + =item $] The version + patchlevel / 1000 of the Perl interpreter. This variable @@ -1003,11 +1019,17 @@ built, as determined during the configuration process. The value is identical to C<$Config{'osname'}>. See also L and the B<-V> command-line switch documented in L. +In Windows platforms, $^O is not very helpful: since it is always +C, it doesn't tell the difference between +95/98/ME/NT/2000/XP/CE/.NET. Use Win32::GetOSName() or +Win32::GetOSVersion() (see L and L) to distinguish +between the variants. + =item ${^OPEN} An internal variable used by PerlIO. A string in two parts, separated -by a C<\0> byte, the first part is the input disciplines, the second -part is the output disciplines. +by a C<\0> byte, the first part describes the input layers, the second +part describes the output layers. =item $PERLDB @@ -1075,9 +1097,15 @@ regular expression assertion (see L). May be written to. =item $^S -Current state of the interpreter. Undefined if parsing of the current -module/eval is not finished (may happen in $SIG{__DIE__} and -$SIG{__WARN__} handlers). True if inside an eval(), otherwise false. +Current state of the interpreter. + + $^S State + --------- ------------------- + undef Parsing module/eval + true (1) Executing an eval + false (0) Otherwise + +The first state may happen in $SIG{__DIE__} and $SIG{__WARN__} handlers. =item $BASETIME @@ -1089,8 +1117,16 @@ and B<-C> filetests are based on this value. =item ${^TAINT} -Reflects if taint mode is on or off (i.e. if the program was run with -B<-T> or not). True for on, false for off. +Reflects if taint mode is on or off. 1 for on (the program was run with +B<-T>), 0 for off, -1 when only taint warnings are enabled (i.e. with +B<-t> or B<-TU>). This variable is read-only. + +=item ${^UNICODE} + +Reflects certain Unicode settings of Perl. See L +documentation for the C<-C> switch for more information about +the possible values. This variable is set during Perl startup +and is thereafter read-only. =item $PERL_VERSION @@ -1131,21 +1167,6 @@ related to the B<-w> switch.) See also L. The current set of warning checks enabled by the C pragma. See the documentation of C for more details. -=item ${^WIDE_SYSTEM_CALLS} - -Global flag that enables system calls made by Perl to use wide character -APIs native to the system, if available. This is currently only implemented -on the Windows platform. - -This can also be enabled from the command line using the C<-C> switch. - -The initial value is typically C<0> for compatibility with Perl versions -earlier than 5.6, but may be automatically set to C<1> by Perl if the system -provides a user-settable default (e.g., C<$ENV{LC_CTYPE}>). - -The C pragma always overrides the effect of this flag in the current -lexical scope. See L. - =item $EXECUTABLE_NAME =item $^X @@ -1219,6 +1240,13 @@ the script. C<$#ARGV> is generally the number of arguments minus one, because C<$ARGV[0]> is the first argument, I the program's command name itself. See C<$0> for the command name. +=item ARGVOUT + +The special filehandle that points to the currently open output file +when doing edit-in-place processing with B<-i>. Useful when you have +to do a lot of inserting and don't want to keep modifying $_. See +L for the B<-i> switch. + =item @F The array @F contains the fields of each line read in when autosplit @@ -1322,6 +1350,10 @@ this: See L. +The delivery policy of signals changed in Perl 5.8.0 from immediate +(also known as "unsafe") to deferred, also known as "safe signals". +See L for more information. + Certain internal hooks can be also set using the %SIG hash. The routine indicated by C<$SIG{__WARN__}> is called when a warning message is about to be printed. The warning message is passed as the first @@ -1454,18 +1486,19 @@ used safely in programs. C<$^_> itself, however, I reserved. Perl identifiers that begin with digits, control characters, or punctuation characters are exempt from the effects of the C -declaration and are always forced to be in package C
. A few -other names are also exempt: +declaration and are always forced to be in package C
; they are +also exempt from C errors. A few other names are also +exempt in these ways: ENV STDIN INC STDOUT ARGV STDERR - ARGVOUT + ARGVOUT _ SIG In particular, the new special C<${^_XYZ}> variables are always taken to be in package C
, regardless of any C declarations -presently in scope. +presently in scope. =head1 BUGS