X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlvar.pod;h=718484f466b539f64538a6b473a72ecffb6daa6d;hb=a0acbdc36d211b2eba42328df555d9ec49fa4cd4;hp=285a0d586315dce7b556407bd329afc2cad104a9;hpb=4ba05bdca841ced94aa583a51f92e8ba338c00d2;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlvar.pod b/pod/perlvar.pod index 285a0d5..718484f 100644 --- a/pod/perlvar.pod +++ b/pod/perlvar.pod @@ -99,7 +99,7 @@ The implicit iterator variable in the grep() and map() functions. =item * -The default place to put an input record when a CFHE> +The default place to put an input record when a C<< >> operation's result is tested by itself as the sole criterion of a C test. Outside a C test, this will not happen. @@ -111,7 +111,7 @@ test. Outside a C test, this will not happen. =over 8 -=item $EIE +=item $> Contains the subpattern from the corresponding set of capturing parentheses from the last pattern match, not counting patterns @@ -174,6 +174,8 @@ example: (Mnemonic: be positive and forward looking.) This variable is read-only and dynamically scoped to the current BLOCK. +=item @LAST_MATCH_END + =item @+ This array holds the offsets of the ends of the last successful @@ -191,17 +193,22 @@ examples given for the C<@-> variable. =item $* -Set to 1 to do multi-line matching within a string, 0 to tell Perl -that it can assume that strings contain a single line, for the purpose -of optimizing pattern matches. Pattern matches on strings containing -multiple newlines can produce confusing results when C<$*> is 0. Default -is 0. (Mnemonic: * matches multiple things.) This variable -influences the interpretation of only C<^> and C<$>. A literal newline can -be searched for even when C<$* == 0>. +Set to a non-zero integer value to do multi-line matching within a +string, 0 (or undefined) to tell Perl that it can assume that strings +contain a single line, for the purpose of optimizing pattern matches. +Pattern matches on strings containing multiple newlines can produce +confusing results when C<$*> is 0 or undefined. Default is undefined. +(Mnemonic: * matches multiple things.) This variable influences the +interpretation of only C<^> and C<$>. A literal newline can be searched +for even when C<$* == 0>. Use of C<$*> is deprecated in modern Perl, supplanted by the C and C modifiers on pattern matching. +Assigning a non-numerical value to C<$*> triggers a warning (and makes +C<$*> act if C<$* == 0>), while assigning a numerical value to C<$*> +makes that an implicit C is applied on the value. + =item input_line_number HANDLE EXPR =item $INPUT_LINE_NUMBER @@ -215,7 +222,7 @@ you just read() (or called a C or C on). The value may be different from the actual physical line number in the file, depending on what notion of "line" is in effect--see C<$/> on how to change that. An explicit close on a filehandle resets the line -number. Because CE> never does an explicit close, line +number. Because C<< <> >> never does an explicit close, line numbers increase across ARGV files (but see examples in L). Consider this variable read-only: setting it does not reposition the seek pointer; you'll have to do that on your own. Localizing C<$.> @@ -412,6 +419,8 @@ channel. Used with formats. (Mnemonic: lines_on_page - lines_printed.) +=item @LAST_MATCH_START + =item @- $-[0] is the offset of the start of the last successful match. @@ -421,7 +430,7 @@ I-th subpattern, or undef if the subpattern did not match. Thus after a match against $_, $& coincides with C. Similarly, C<$>I coincides with CIC<], $+[>IC<] - $-[>IC<]> if C<$-[>IC<]> is defined, and $+ coincides with -C. One can use C<$#E<45>> to find the last +C. One can use C<$#-> to find the last matched subgroup in the last successful match. Contrast with C<$#+>, the number of subgroups in the regular expression. Compare with C<@+>. @@ -439,17 +448,17 @@ After a match against some variable $var: =over 5 -=item C<$`> is the same as C) +=item C<$`> is the same as C -=item C<$&> is the same as C) +=item C<$&> is the same as C -=item C<$'> is the same as C) +=item C<$'> is the same as C =item C<$1> is the same as C =item C<$2> is the same as C -=item C<$3> is the same as C) +=item C<$3> is the same as C =back @@ -511,7 +520,7 @@ The status returned by the last pipe close, backtick (C<``>) command, successful call to wait() or waitpid(), or from the system() operator. This is just the 16-bit status word returned by the wait() system call (or else is made up to look like it). Thus, the -exit value of the subprocess is really (C<$? EE 8>), and +exit value of the subprocess is really (C<<< $? >> 8 >>>), and C<$? & 127> gives which signal, if any, the process died from, and C<$? & 128> reports whether there was a core dump. (Mnemonic: similar to B and B.) @@ -615,7 +624,8 @@ across fork() calls. (Mnemonic: same as shells.) =item $< The real uid of this process. (Mnemonic: it's the uid you came I, -if you're running setuid.) +if you're running setuid.) You can change both the real uid and +the effective uid at the same time by using POSIX::setuid(). =item $EFFECTIVE_USER_ID @@ -628,8 +638,11 @@ The effective uid of this process. Example: $< = $>; # set real to effective uid ($<,$>) = ($>,$<); # swap real and effective uid +You can change both the effective uid and the real uid at the same +time by using POSIX::setuid(). + (Mnemonic: it's the uid you went I, if you're running setuid.) -C<$E> and C<$E> can be swapped only on machines +C<< $< >> and C<< $> >> can be swapped only on machines supporting setreuid(). =item $REAL_GROUP_ID @@ -648,6 +661,9 @@ However, a value assigned to C<$(> must be a single number used to set the real gid. So the value given by C<$(> should I be assigned back to C<$(> without being forced numeric, such as by adding zero. +You can change both the real gid and the effective gid at the same +time by using POSIX::setgid(). + (Mnemonic: parentheses are used to I things. The real gid is the group you I, if you're running setgid.) @@ -670,10 +686,13 @@ empty list for setgroups(), just repeat the new effective gid; that is, to force an effective gid of 5 and an effectively empty setgroups() list, say C< $) = "5 5" >. +You can change both the effective gid and the real gid at the same +time by using POSIX::setgid() (use only a single numeric argument). + (Mnemonic: parentheses are used to I things. The effective gid is the group that's I for you, if you're running setgid.) -C<$E>, C<$E>, C<$(> and C<$)> can be set only on +C<< $< >>, C<< $> >>, C<$(> and C<$)> can be set only on machines that support the corresponding I routine. C<$(> and C<$)> can be swapped only on machines supporting setregid(). @@ -687,6 +706,11 @@ program sees. This is more useful as a way of indicating the current program state than it is for hiding the program you're running. (Mnemonic: same as B and B.) +Note for BSD users: setting C<$0> does not completely remove "perl" +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. + =item $[ The index of the first element in an array, and of the first character @@ -699,8 +723,6 @@ As of release 5 of Perl, assignment to C<$[> is treated as a compiler directive, and cannot influence the behavior of any other file. Its use is highly discouraged. -=item $PERL_VERSION - =item $] The version + patchlevel / 1000 of the Perl interpreter. This variable @@ -713,7 +735,10 @@ of perl in the right bracket?) Example: See also the documentation of C and C for a convenient way to fail if the running Perl interpreter is too old. -See C<$^V> for a more modern representation of the Perl version. +The use of this variable is deprecated. The floating point representation +can sometimes lead to inaccurate numeric comparisons. See C<$^V> for a +more modern representation of the Perl version that allows accurate string +comparisons. =item $COMPILING @@ -813,10 +838,10 @@ Then $^M = 'a' x (1 << 16); -would allocate a 64K buffer for use when in emergency. See the +would allocate a 64K buffer for use in an emergency. See the F file in the Perl distribution for information on how to enable this option. To discourage casual use of this advanced -feature, there is no L long name for this variable. +feature, there is no L long name for this variable. =item $OSNAME @@ -905,24 +930,23 @@ The time at which the program began running, in seconds since the epoch (beginning of 1970). The values returned by the B<-M>, B<-A>, and B<-C> filetests are based on this value. -=item $PERL_VERSION_TUPLE +=item $PERL_VERSION =item $^V The revision, version, and subversion of the Perl interpreter, represented -as a "version tuple". Version tuples have both a numeric value and a -string value. The numeric value is a floating point number that amounts -to revision + version/1000 + subversion/1000000, and the string value -is made of characters possibly in the UTF-8 range: -C. +as a string composed of characters with those ordinals. Thus in Perl v5.6.0 +it equals C and will return true for +C<$^V eq v5.6.0>. Note that the characters in this string value can +potentially be in Unicode range. This can be used to determine whether the Perl interpreter executing a script is in the right range of versions. (Mnemonic: use ^V for Version -control.) Example: +Control.) Example: - warn "No "our" declarations!\n" if $^V and $^V lt v5.6; + warn "No "our" declarations!\n" if $^V and $^V lt v5.6.0; -See also the documentation of C and C +See the documentation of C and C for a convenient way to fail if the running Perl interpreter is too old. See also C<$]> for an older representation of the Perl version. @@ -964,7 +988,7 @@ This may not be a full pathname, nor even necessarily in your path. =item $ARGV -contains the name of the current file when reading from EE. +contains the name of the current file when reading from <>. =item @ARGV @@ -1134,7 +1158,7 @@ the value of $@ is the compile error, or the argument to C (which will interpolate C<$!> and C<$?>!). (See also L, though.) -When the eval() expression above is executed, open(), C<>, +When the eval() expression above is executed, open(), C<< >>, and C are translated to calls in the C run-time library and thence to the operating system kernel. C<$!> is set to the C library's C if one of these calls fails. @@ -1211,7 +1235,7 @@ expression matches in a program, regardless of whether they occur in the scope of C. For that reason, saying C in libraries is strongly discouraged. See the Devel::SawAmpersand module documentation from CPAN -(http://www.perl.com/CPAN/modules/by-module/Devel/Devel-SawAmpersand-0.10.readme) +(http://www.perl.com/CPAN/modules/by-module/Devel/) for more information. Having to even think about the C<$^S> variable in your exception