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--- notes:perl_cheat_sheet [2026/07/18 06:25]
114.119.135.37 old revision restored (2026/06/25 08:11)
+++ notes:perl_cheat_sheet [2026/07/24 13:03] (current)
47.79.201.51 old revision restored (2026/06/15 21:28)
@@ Line 14: / Line 14: @@
   * Parenthesis are optional unless part of syntax.
   * ''@ARGV'' contains arguments, $0 contains program name.
-      * * die can be used to exit early $! will contain any system error message. Without \n at the end, perl will append line number to error message.
+  * ''die''/''warn'' can be used to exit/warn, $! will contain any system error message. Without \n at the end, perl will append line number to error message.
 ===== Numbers =====
@@ Line 91: / Line 91: @@
   * ''<>'' iterates over all files in @ARGV (or STDIN if no args) like e.g. cat/sed/awk. <code perl>while (<>) {
     chomp;
-    print "It was $_ that I saw!\n";
+    print LOGFILE "It was $_ that I saw!\n";
 }</code>
   * ''print'' takes list of items and sends all to STDOUT (unseparated). ''print @array;'' vs ''print "@array";'' <code perl>print <>;          # source code for 'cat'
@@ Line 103: / Line 103: @@
 open BEDROCK, '>fred' || die "Cannot open fred: $!";
 open LOG, '>>:encoding(UTF-8)','logfile'; # for perl >= 5.6
-open BEDROCK, '>:crlf', $file_name; # DOS-formatted output
+open my $bedrock, '>:crlf', $file_name; # DOS-formatted output
 binmode STDOUT, ':encoding(UTF-8)';</code>
+  * ''select'' can be used to change default output filehandle. ''$| = 1;'' unbuffers currently selected output.
 ===== User Subroutines =====

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