Perl module File:Slurp with STDIN piped

Question

I have just tried using the following Perl script to do some text substitution using the File::Slurp module. It works fine on a single file given as an argument at the command line (BASH).

#!/opt/local/bin/perl -w

use File::Slurp qw( edit_file_lines );

foreach my $argnum (0 .. $#ARGV) {
  edit_file_lines { 
    s/foo/bar/g; 
    print $_
  } 
  $ARGV[$argnum];
}

I would like to alter it to cope also with pipes (i.e. STDIN), so that it can be in the middle of a series of piped operations: for example:

command blah|....|my-perl-script|sort|uniq|wc....

What is the best way to change the Perl script to allow this, whilst retaining the existing ability to work with single files on the command line?

Answer 1

To have your script work in a pipeline, you could check if STDIN is connected to a tty:

use strict;
use warnings;
use File::Slurp qw( edit_file_lines );

sub my_edit_func {  s/foo/bar/g;  print $_ }

if ( !(-t STDIN) ) {
    while(<>) { my_edit_func }
}
else {
    foreach my $argnum (0 .. $#ARGV) {
        edit_file_lines { my_edit_func } $ARGV[$argnum];
    }
}

See perldoc -X for more information on the -t file test operator.