[Perl] Accessing array elements within a sed command in Perl script Post: 302243017

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Top Forums Shell Programming and Scripting [Perl] Accessing array elements within a sed command in Perl script Post 302243017 by SFNYC on Friday 3rd of October 2008 12:05:25 PM

10-03-2008

Registered User

Like otheus said, why use sed in a Perl script? If you are going to use Perl, you had better learn how to use it properly. Otherwise stick with sed.

Here's a small Perl script that will do what you want and create a backup file to boot.

I called this replace.pl

Code:

#!/usr/bin/perl

use strict;
use warnings;
use English qw( -no_match_vars );

my $old;
my $new;
my $oldFH;
my $newFH;
my $dirDH;

my $dir = ".";  #Use current directory

opendir($dirDH, $dir) or die "Cannot opendir $dir\n";

my @test = readdir($dirDH);

foreach $old (@test) {
    next if $old eq '.';  #skip directory entries
    next if $old eq '..';

    $new = "$old.temp";
    open($oldFH, "<", $old)        or die "can't open $old: $OS_ERROR\n";
    open($newFH, ">", $new)        or die "can't open $new: $OS_ERROR\n";
    while (<$oldFH>) {
        $_ =~ s/BIOGRF  321/BIOGRF  332/g;
        print $newFH $_            or die "can't write $new: $OS_ERROR\n";
    }

    close($oldFH)                  or die "can't close $old: $OS_ERROR\n";
    close($newFH)                  or die "can't close $new: $OS_ERROR\n";
    rename($old, "$old.orig")      or die "can't rename $old to $old.orig: $OS_ERROR\n";
    rename($new, $old)             or die "can't rename $new to $old: $OS_ERROR\n";

}

closedir($dirDH) or die "Cannot closedir $dir\n";

exit 0;

Output:

Code:

$ ls -1
test1
test2
test3
test4

$ cat test1 test2 test3 test4
BIOGRF  321
BIOGRF  421
BIOGRF  32X
BIOGRF  199

$ replace.pl

$ cat test1 test2 test3 test4
BIOGRF  332
BIOGRF  421
BIOGRF  32X
BIOGRF  199


$ ls -1
test1
test1.orig
test2
test2.orig
test3
test3.orig
test4
test4.orig

The guts of the code comes from The Perl Cookbook. I just wrapped it around a loop that takes all the files from the current directory and performs your replace command. In your case you just need the while loop that walks through your array called @test.

SFNYC

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LEARN ABOUT CENTOS

perl::critic::policy::modules::requirenomatchvarswithuseenglish

Perl::Critic::Policy::Modules::RequireNoMatchVarsWithUseUseriContributed Perl DoPerl::Critic::Policy::Modules::RequireNoMatchVarsWithUseEnglish(3)

NAME

       Perl::Critic::Policy::Modules::RequireNoMatchVarsWithUseEnglish - "use English" must be passed a "-no_match_vars" argument.

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       Due to unfortunate history, if you use the English module but don't pass in a "-no_match_vars" argument, all regular expressions in the
       entire program, not merely the module in question, suffer a significant performance penalty, even if you only import a subset of the
       variables.

	   use English; 			     # not ok
	   use English '-no_match_vars';	     # ok
	   use English qw< $ERRNO -no_match_vars >;  # ok
	   use English qw($OS_ERROR);		     # not ok

       In the last example above, while the match variables aren't loaded into your namespace, they are still created in the "English" namespace
       and you still pay the cost.

CONFIGURATION

       This Policy is not configurable except for the standard options.

AUTHOR

       Elliot Shank "<perl@galumph.com>"

COPYRIGHT

       Copyright (c) 2008-2011 Elliot Shank.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.  The full text of this license
       can be found in the LICENSE file included with this module.

perl v5.16.3							    2014-06-09	Perl::Critic::Policy::Modules::RequireNoMatchVarsWithUseEnglish(3)

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