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narwahl
Asked: 2017-03-03 21:59:03 +0800 CST

Linux equivalent of Unix who -m command, to show original user ID before su?

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I'm trying to find a Linux equivalent of running who -m in Unix. In Unix, who -m gives the first user ID you used to log in, before starting any new shell sessions through su, etc.

The -m switch to who has a different effect in Linux, and I'm unable to find anything relevant to my needs in the man pages so far.

linux unix security identity-management login-script

1 Answers

  1. Best Answer

    Update: My answer (who am i) is correct, your terminal is either broken or not configured correctly to support the functionality.

    Based on the comments, I've done some more research and I asked a friend to help. You don't say which terminal you are using but it's likely doing the same thing as gnome-terminal.

    In respect of gnome-terminal* when the terminal is started, it does not update the utmp file. This appears to be a design decision. Later when who reads utmp to find out the relevant information it's not there so it just exits and prints nothing.

    * I tries xterm, konsole and ssh to various distros.

    You want who am i which prints the invoking user as opposed to whoami which tells you the username of the current effective user

    If given two non-option arguments, 'who' prints only the entry for the user running it (determined from its standard input), preceded by the hostname. Traditionally, the two arguments given are 'am i', as in 'who am i'.

    That is buried in info coreutils 'who invocation' So interestingly (on a linux coreutils based system) who xyzzy plugh works as well.

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