Source code for cut.pl

#! perl

$syntax = "\nCut.pl,  Version 1.11\nPort of Unix' CUT command\n\n";

$syntax = $syntax."Usage:\n\nany_cmd | PERL CUT.PL [-DEBUG] ";

$syntax = $syntax."{-C:n|-F:n [-D:'any_string' [-I]]} [-L:n] [-S]\n\n";

$syntax = $syntax."Argument:           Function:";

$syntax = $syntax."                                 Dependency:\n";

$syntax = $syntax."=========           =========";

$syntax = $syntax."                                 ===========\n";

$syntax = $syntax."any_cmd             command that's output is to be parsed";

$syntax = $syntax."\n-DEBUG              display intermediate results\n";

$syntax = $syntax."                    (preferably the first argument)\n";

$syntax = $syntax."-C:<column_number>  parse by Columns or Characters\n";

$syntax = $syntax."-D:'<delimiter>'    Delimiter character or string";

$syntax = $syntax."             -F\n";

$syntax = $syntax."                    (should be escaped if necessary)\n";

$syntax = $syntax."-F:<field_number>   parse by Fields or words\n";

$syntax = $syntax."-I                  case Insensitive delimiter";

$syntax = $syntax."                -D\n";

$syntax = $syntax."-L:<length>         number of characters or words ";

$syntax = $syntax."to display  -C\n";

$syntax = $syntax."-S                  Skip blank lines in result\n\n";

$syntax = $syntax."Written by Rob van der Woude\n";

$syntax = $syntax."http://www.robvanderwoude.com\n";

# Assign default values

$case  = 1;

$debug = 0;

$delim = "\\s";

$help  = 0;

$len   = 0;

$skip  = 0;

# Command line parsing is SO much easier using regular expressions

foreach $_ ( @ARGV ) {

	if ( $debug == 1 ) {

		print "$_\n";

	}

	SWITCH: {

		if ( $_ =~ m/^-C:(\d+)$/i ) {

			$type = "char";

			$char = $1;

			last SWITCH;

		}

		if ( $_ =~ m/^-D:\'?([^.']+)\'?$/i ) {

			$delim = $1;

			last SWITCH;

		}

		if ( $_ =~ m/^-DEBUG$/i ) {

			$debug = 1;

			print "\nCommand line arguments:\n$_\n";

			last SWITCH;

		}

		if ( $_ =~ m/^-F:(\d+)$/i ) {

			$type = "word";

			$word = $1;

			last SWITCH;

		}

		if ( $_ =~ m/^-I$/i ) {

			$case = 0;

			last SWITCH;

		}

		if ( $_ =~ m/^-L:(\d+)$/i ) {

			$len = $1;

			last SWITCH;

		}

		if ( $_ =~ m/^-S$/i ) {

			$skip = 1;

			last SWITCH;

		}

		$help = 1;

	}

}

if ( !@ARGV[0] or ( $help == 1 ) ) {

	print $syntax;

	exit(1);

}

# Debug info

if ( $debug == 1 ) {

	print "\nInterpretation of command line arguments:\n";

	print "\$case=$case\n\$char=$char\n\$delim=$delim\n";

	print "\$len=$len\n\$skip=$skip\n\$type=$type\n\$word=$word\n";

}

# Create the regular expressions to parse ("cut") the string

$re = "^";

if ( $type eq "word" ) {

	if ( $case == 0 ) {

		$re = $re."^(?i)";

	}

	$re = $re."(?:$delim)*";

	if ( $word > 1 ) {

		for ( $i = 1; $i < $word; $i++ ) {

			$re = $re."[^$delim]+(?:$delim)+";

		}

	}

	$re  = $re."(";

	$re0 = $re.".*)\$";

	if ( $len > 0 ) {

		$re = $re."[^$delim]+";

		for ( $i = 1; $i < $len; $i++ ) {

			$re = $re."(?:$delim)+[^$delim]+";

		}

		$re = $re.")(?:$delim)";

	} else {

		$re = $re0;

	}

	if ( $case == 0 ) {

		$re = $re."(?-i)";

	}

} else {

# if ( $type eq "char" ) {

	if ( $char > 0 ) {

		$re  = $re.".{".( $char - 1 )."}";

		$re0 = $re."(.*)\$";

	}

	if ( $len > 0 ) {

		$re = $re."(.{0,$len})";

	} else {

		$re = $re0;

	}

}

# Debug info

if ( $debug == 1 ) {

	print "\nRegular Expression:\n$re\n";

	print "\nStandard input \& \"cut\" result:\n";

}

# Parse STDIN and display results

while ( <STDIN> ) {

	chomp $_;

	if ( $debug == 1 ) {

		print "STDIN: $_\n";

	}

	$m = $_;

	if ( $_ =~ $re ) {

		print "$1\n";

	} elsif ( $_ =~ $re0 ) {

		print "$1\n";

	} elsif ( $skip == 0 ) {

		print "\n";

	}

}