#!/usr/bin/awk -f

# Assign a new uid for users that have uid=0
BEGIN {
    FS=":";
    max_uid = 0;
    i = 0;
}

{
    max_uid = ($3 > max_uid ? $3 : max_uid);
    if ($3 == "0") {
        uid0[i] = $0;
    } else {
        good[i] = $0;
    }
    i += 1;
}

END {
    for (i in good) {
        print good[i];
    }

    for (i in uid0) {
        max_uid += 1;
        split(uid0[i], f, ":");
        print f[1]":"f[2]":"max_uid":"f[4]":"f[5]":"f[6]":"f[7];
    }
}