cuserid - Linux


cuserid is a command-line tool used to retrieve the effective username of the current user. It is commonly used in scripts and programs that require the current user’s identity for authentication or authorization purposes.


cuserid [options]


The following options are available:

  • -R, –real-id: Retrieve the real user ID instead of the effective user ID.
  • -g, –group-id: Append the effective group ID to the output.
  • -G, –groups: Append the supplementary group IDs to the output.


  • Retrieve the effective username:

  • Retrieve the real user ID:

    cuserid -R
  • Retrieve the effective username and group ID:

    cuserid -g
  • Retrieve the effective username and all group IDs:

    cuserid -G

Common Issues

  • No output: If no output is displayed, the command may have failed. Verify that the user is correctly authenticated and has sufficient permissions.
  • Incorrect username: If the displayed username is incorrect, the user’s environment may be misconfigured. Check the /etc/passwd file for any inconsistencies.


cuserid can be used in conjunction with other commands to automate tasks. For example, it can be used with sudo to run commands with elevated privileges:

sudo -u $(cuserid) command

Related Commands

  • whoami: Displays the effective username.
  • id: Displays the user’s ID, group ID, and other related information.