Linux System Administration Recipes A Problem-Solution Approach

APPENDIX ■ PERL TIPSPerl Syntax NotesHere are a few brief notes about a couple of the corners of Perl syntax that I often find myself havingto refer to the documentation for. Remember, however, the Perl maxim: there’s more than one way todo it!open with |To get command output, you can use open with a pipe, as shown in recipe 4-2:open FILEHANDLE, '-|', 'command';while () {# do stuff!}This will pipe the output from command into FILEHANDLE, which the while() loop then iterates overline by line. If you use '|-' instead, the output from FILEHANDLE is piped to command.?:This syntax, which basically provides an if-then-else shorthand for assignments, can be useful.If the value before ? evaluates as true, then the value after ? is used for assignment; otherwise, the valueafter : is used. So this statement:my $a = $ok ? $b : $c;is a shorthand for this:my $a;if ($ok) {$a = $b;} else {$a = $c;}Use this with caution; it can be a neat way of doing things, but if you find yourself scatteringparentheses everywhere and/or having to look at it more than once to understand it, go back to thelonger version.251Download at WoweBook.Com