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markhorrocks
Asked: 2015-04-07 13:48:16 +0800 CST

How do I find out if a uid exists?

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I have added a new user in Ubuntu using puppet with a hard coded uid of 10017. The uids must be the same across workstations so that when user data is restored everything lines up.

Now I find out that uid is not unique. Mysql is using it. How can I test a server to find out if a uid (10018) exists?

ubuntu

2 Answers

  1. Best Answer

    Answering the specific question (how do I tell if a uid is in use) ...

    getent passwd 1234

    Will exit with 0 if uid is in use and 2 if not. As Mark says it will also output any matching entries. When using within a shell script I'd expect to discard the output and just test the exit code.

    Note that using getent has the advantage of any techniques that look at /etc/passwd directly because it will also consult any other data sources you have configured (NIS, LDAP etc).

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  2. cat /etc/passwd | awk -F: '{print $3}' | sort -n
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