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Perl Cookbook by Nathan Torkington, Tom Christiansen

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Renaming Files

Problem

You have a lot of files whose names you want to change.

Solution

Use a foreach loop and the rename function:

foreach $file (@NAMES) {
    my $newname = $file;
    # change $newname
    rename($file, $newname) or  
        warn "Couldn't rename $file to $newname: $!\n";
}

Discussion

This is straightforward. rename takes two arguments. The first is the filename to change, and the second is its new name. Perl’s rename is a front end to the operating system’s rename system call, which typically won’t let you rename files across filesystem boundaries.

A small change turns this into a generic rename script, such as the one by Larry Wall shown in Example 9.5.

Example 9-5. rename

#!/usr/bin/perl -w
# rename - Larry's filename fixer
$op = shift or die "Usage: rename expr [files]\n";
chomp(@ARGV = <STDIN>) unless @ARGV;
for (@ARGV) {
    $was = $_;
    eval $op;
    die $@ if $@;
    rename($was,$_) unless $was eq $_;
}

This script’s first argument is Perl code that alters the filename (stored in $_) to reflect how you want the file renamed. It can do this because it uses an eval to do the hard work. It also skips rename calls when the filename is untouched. This lets you simply use wildcards like rename EXPR * instead of making long lists of filenames.

Here are five examples of calling the rename program from your shell:

% rename 's/\.orig$//' *.orig % rename 'tr/A-Z/a-z/ unless /^Make/' * % rename '$_ .= ".bad"' *.f % rename 'print "$_: "; s/foo/bar/ if <STDIN> =~ /^y/i' * % find /tmp -name '*~' -print | rename ...

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