=over =item $PROGRAM_NAME =item $0 X<$0> X<$PROGRAM_NAME> Contains the name of the program being executed. On some (but not all) operating systems assigning to C<$0> modifies the argument area that...

=over =item $EXECUTABLE_NAME =item $^X X<$^X> X<$EXECUTABLE_NAME> The name used to execute the current copy of Perl, from C's C<argv[0]> or (where supported) F</proc/self/exe>. Depending on the hos...

=over =item $[ X<$[> This variable stores the index of the first element in an array, and of the first character in a substring. The default is 0, but you could theoretically set it to 1 to make Pe...

=over =item fc EXPR X<fc> X<foldcase> X<casefold> X<fold-case> X<case-fold> =item fc Returns the casefolded version of EXPR. This is the internal function implementing the C<\F> escape in double-qu...

=over =item close FILEHANDLE X<close> =item close Closes the file or pipe associated with the filehandle, flushes the IO buffers, and closes the system file descriptor. Returns true if those operat...

=over =item @LAST_MATCH_START =item @- X<@-> X<@LAST_MATCH_START> This array holds the offsets of the beginnings of the last successful match and any capture buffers it contains. (See L</Scoping Ru...

=over =item next LABEL X<next> X<continue> =item next EXPR =item next The L<C<next>|/next LABEL> command is like the C<continue> statement in C; it starts the next iteration of the loop: LINE: whil...

=over =item grep BLOCK LIST X<grep> =item grep EXPR,LIST This is similar in spirit to, but not the same as, L<grep(1)> and its relatives. In particular, it is not limited to using regular expressio...

=over =item ucfirst EXPR X<ucfirst> X<uppercase> =item ucfirst Returns the value of EXPR with the B<first> character in uppercase (Unicode calls this titlecase). If EXPR is omitted, C<ucfirst> uses...

=over =item cos EXPR X<cos> X<cosine> X<acos> X<arccosine> =item cos Returns the cosine of EXPR (expressed in radians). If EXPR is omitted, takes the cosine of L<C<$_>|perlvar/$_>. For the inverse ...