I'm trying to add a user (as root) on CentOS 5.5 and I've got this message : useradd: unable to lock password file After reading some post linked to this issue I've deleted two files in /etc : .pwd.lock passwd- However it still doesn't work. Finally, I read a thread where the guy said that using the passwd command to update the passwd file and normally fix this issue. I've tried with the root user But I've got this issue : passwd: Authentication token manipulation error Any idea to add my user ?