Changing Ownership (Learning Perl, 3rd Edition)

13.6. Changing Ownership

If the operating system permits it, you may change the ownership and group membership of a list of files with the chown function. The user and group are both changed at once, and both have to be the numeric user-ID and group-ID values. For example:

my $user = 1004;
my $group = 100;
chown $user, $group, glob "*.o";

What if you have a username like merlyn instead of the number? Simple. Just call the getpwnam function to translate the name into a number, and the corresponding getgrnam[297] to translate the group name into its number:

[297]These two are among the ugliest function names known to mankind. But don't blame Larry for them; he's just giving them the same names that the folks at Berkeley did.

defined(my $user = getpwnam "merlyn") or die "bad user";
defined(my $group = getgrnam "users") or die "bad group";
chown $user, $group, glob "/home/merlyn/*";

The defined function verifies that the return value is not undef, which will be returned if the requested user or group is not valid.

The chown function returns the number of files affected, and it sets $! on error.