Tip: mimic user file permissions to group

I ran into a situation the other day where I had setup a git repository for myself and wanted to grant read/write access to another fellow who is helping out on the project. He could pull from the repository just fine, but couldn't push to it because the directory permissions on the repo were only setup for me to write to.

After creating a new group for us, adding our user ids to it and then doing a recursive chgrp on the repo I realized that by default git repositories are not setup for group writes unless you explicitly specify that at the time of creations (i.e. git init --shared=group. So I really needed a way to recursively mirror the user's file permissions on all files and directories in the repo to that of the group.

Searching long and hard I could not find a canned solution to this, perhaps one exists out there but because "mimic user file permissions to group" and "mirror user file permissions to group" don't yield good results in google, I was forced to write my own Perl script:

#!/usr/bin/perl
use File::stat;
use Fcntl ':mode';

foreach (@ARGV) {
    next unless -e $_;
    $stats = stat($_);
    $mode = substr(sprintf("%04o", $stats->mode), -3);
    $out = "$_ from $mode to ";
    $mode =~ s/(\d)(\d)(\d)/$1$1$3/;
    $out = "$out $mode";
    printf($out . "\n");
    chmod oct($mode), $_;
}

The Usage on this script is:

mimicuserperms.pl 

To use it recursively:

find . -exec mimicuserperms.pl {} \;

DISCLAIMER: Not sure if this will work on every single system out there, I mean it literally just grabs the last three file perms found by stat and takes the first character and duplicates it over the second. So use at your own risk! Perhaps, backup whatever you are going to use this on first before trying.