How to Rename a Linux User

What if after installing a Linux OS you found that you made a typo in the username. Reinstalling the whole OS just to fix a typo doesn’t sound rational.

One solution can be removing the wrong user and creating a new one, with a correct name. But in that case, all programs that had configs in the user’s home directory will be messed up, which is very bad.

The correct way of renaming a Linux user and his home directory is to use the usermod command:

🚀 ~ usermod -l <new_username> <old_username>

Then, we need to set a home directory for our new user:

🚀 ~ usermod -md /home/<new_username> <new_username>

Here, the -d flag sets the home directory for our new user, and the -m flag moves all contents from the old user’s home directory.

We also need to change the user’s default group, which is the same as the username in most cases:

🚀 ~ groupmod -n <new_username> <old_username>

And, finally, if your hostname is like <username-desktop> or similar, you might want to change it, too. You need to edit both /etc/hostname and /etc/hosts files to do that.

🚀 ~ echo <new_username>-desktop | tee /etc/hostname # or 'sudo tee'

# backup first
🚀 ~ cp /etc/hosts /etc/hosts.bak
# then
🚀 ~ sed -i 's/<old_username>/<new_username>/gI' /etc/hosts

Important! All commands above need to run under root or with sudo.

Important! The changes in /etc/hostname and /etc/hosts will take effect only after rebooting the system.

Important! If you want to rename the currently logged-in user, then it won’t work because that user is used by certain processes. The workaround here is to switch to Virtual Console (Ctrl+Alt+F1-F6), log in as root, kill all that processes with kill <pid>, do the necessary operations of renaming the user, and re-login again by switching to GUI login screen (Ctrl+Alt+F7).

References

“How to rename Linux users and their home directory” by Shane Rainville (August 28, 2020) 

“Ubuntu Linux Change Hostname (computer name)” by Vivek Gite (August 19, 2020) 

“How to use sed to find and replace text in files in Linux / Unix shell” by Vivek Gite (January 13, 2018)