cat.pl

#!/usr/bin/perl -w

use strict;
use warnings;
use Getopt::Long;
use File::Basename;
#use Smart::Comments;

my $index = 0;
my $linenum = 1;
my $script = basename $0;
my $debug = 0;
my ($all, $num_nonblank, $number, $tab, $end, $help, $version);
my ($squeeze_blank, $blank);
my $myversion = "0.2.0";

my $Usage = "
Usage: $script [option]... [file]...
Concatenate FILE(s), or standard input, to standard output.

  -A, --show-all           equivalent to -vET
  -b, --number-nonblank    number nonempty output lines, overrides -n
  -e                       equivalent to -vE
  -E, --show-ends          display \$ at end of each line
  -n, --number             number all output lines
  -s, --squeeze-blank      suppress repeated empty output lines
  -t                       equivalent to -vT
  -T, --show-tabs          display TAB characters as ^I
  -u                       (ignored)
  -v, --show-nonprinting   use ^ and M- notation, except for LFD and TAB
      --help     display this help and exit
      --version  output version information and exit

With no FILE, or when FILE is -, read standard input.

Examples:
  cat f - g  Output f\'s contents, then standard input, then g\'s contents.
  cat        Copy standard input to standard output.
";

GetOptions(
    'show-all|A'  => \$all,
    'number-nonblank|b' => \$num_nonblank,
    'number|n!'   => \$number,  #the '!' means can use --[no]number disable -n option
    'squeeze-blank|s'   => \$squeeze_blank,
    'show-ends|E' => \$end,
    'show-tabs|T' => \$tab,
    'help|h'      => \$help,
    'version|v'   => \$version,
    'debug|d'     => \$debug  # use for debug, turn on Smart::Comments;
);

## $eee

if($debug) {
    # use Smart::Comments;
}

my @files = @ARGV;

if($help or $version) {
    if($version) {
        print "$script version $myversion\n";
    }
    &usage();
}

if($all) {
    $end = 1;
    $tab = 1;
}

if($num_nonblank) {
    $number = 1;
}
$blank = 0;

while(my $line = <>)
{
    if($line =~ /^\s*$/) {
        if($squeeze_blank) {
            if($blank) {
                next;
            }
        }

        if($tab) {
            $line =~ s/\t/\^I/sg;
        }

        if($end) {
            $line =~ s/(\n|\n\r)/\$$1/;
        }

        if($num_nonblank) {
            print "$line";
            $blank = 1;
            next;
        }

        if($number) {
            printf ("%6d  ", $linenum++);
        }

        print "$line";
        $blank = 1;
    } else {
        if($number) {
            printf ("%6d  ", $linenum++);
        }

        if($tab) {
            $line =~ s/\t/\^I/sg;
        }

        if($end) {
            $line =~ s/(\n|\n\r)/\$$1/;
        }

        print $line;
        $blank = 0;
    }

    if(eof) {
        print("--------end of $files[$index] file--------\n");
        $index += 1;
    }
}

sub usage {
    print $Usage;
    exit;
}

### @files
### $index
### $tab
### @ARGV
### $number
### $help
### $debug