On older Perl's, what if your directory exceeds the limit of the shell?

And before using glob freely, I like worrying about what happens if someone use a space in a path. I see no reason to open myself up to that.

As you can tell, I like to be the kind of person who anticipates potential problems and heads them off at the pass. So even though it isn't so short, I tend to use an explicit opendir/readdir/grep solution rather than globbing. YMMV.

while(<*.old>){
    ($new = $_) =~ s/old$/new/;
    rename($_,$new);
}
[download]

$_.=($=+(6<<1));print(chr(my$a=$_));$^H=$_+$_;$_=$^H;
print chr($_-39); # Easy but its ok.
[download]

For a very flexible approach to renaming see the cookbook, recipe 9.9:

#!/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 $_;
}
[download]

% rename 's/\.orig$//'  *.orig
% rename 'tr/A-Z/a-z/ unless /^Make/'  *
% rename '$_ .= ".bad"'  *.f
% rename 'print "$_: "; s/foo/bar/ if <STDIN> =~ /^y/i'  *
% find /tmp -name '*~' -print | rename 's/^(.+)~$/.#$1/'
[download]

-- Hofmator

I always figured, if you're going to do it, do it right:

#!/usr/bin/perl

use strict;

my $pattern = shift @ARGV;

my ($src, $dest) = 
    ($pattern =~ m/^s(.)([^\1]*)\1([^\1]*)\1$/)
    or die "1st arg not s/// construct (or construct too complicated)"
+;

my %to_rename;

for my $f (@ARGV) {
    (! -e $f) && die "$f does not exist; $!";
    my $n = $f;
    $n =~ s/$src/$dest/;
    ( -e $n or defined $to_rename{$n})
        && die "$f would be renamed to $n; clobber detected";
    $to_rename{$n} = $f;
}

while (my ($n, $f) = each %to_rename) {
    rename $f, $n or warn "Cannot rename $f to $n; $!";
}
[download]

OK, I can see bad style there, but it works. I wrote it some time ago...

I called the script ~mv, and it is called as ~mv s/\.old$/.new/ *.old

while($f=<*.old>){rename $f, substr($f,0,-3).'new'}
[download]

This would not work for file with extensions longer than 3 characters (eg any .html file). Not that I really need to point that out...

note: happy 100th node, me