#!/usr/bin/env perl
# This helper script makes it easy to use a passwd or group file to map
# values in a LOCAL transfer.  For instance, if you mount a backup that
# does not have the same passwd setup as the local machine, you can do
# a copy TO the backup area as follows and get the differing ID values
# mapped just like a remote transfer TO the backed-up machine would do:
#
# rsync -av --usermap=`mapto /mnt/backup/etc/passwd` \
#           --groupmap=`mapto /mnt/backup/etc/group` \
#           /some/src/ /mnt/backup/some/dest/

while (<>) {
    push @_, "$1:$2" if /^(\w+):[^:]+:(\d+)/;
}
print join(',', @_), "\n";