Programming Perl, 4th Edition

chown

chown LIST

This function changes the owner and group of a list of files. The first two elements of the list must be the numeric UID and GID, in that order. A value of –1 in either position is interpreted by most systems to leave that value unchanged. The function returns the number of files successfully changed. For example:

chown($uidnum, $gidnum, "file1", "file2") == 2
        || die "can't chown file1 || file2: $!";

will set $cnt to 0, 1, or 2, depending on how many files got changed (in the sense that the operation succeeded, not in the sense that the owner was different afterward). Here’s a more typical usage:

chown($uidnum, $gidnum, @filenames) == @filenames
        || die "can't chown @filenames: $!";

Here’s a subroutine that accepts a username, looks up the user and group IDs for you, and does the chown:

sub chown_by_name {
    my($user, @files) = @_;
    chown((getpwnam($user))[2,3], @files) == @files
            || die "can't chown @files: $!";
}

chown_by_name("fred", glob("*.c"));

However, you may not want the group changed as the previous function does, because the /etc/passwd file associates each user with a single group even though that user may be a member of many secondary groups according to /etc/group ...