change-uid

Anonymous (anonymous@undisclosed.example.com) — 2025-10-11T13:48:27+00:00

Changing a User's UID

Having consistency of UID and GID on UNIX is extremely important if you have multiple servers and clients that you want to maintain a consistent identity on. Be it for NFS, Git, or any other administrative task. Having the same IDs for your users across different computers really helps.

Sadly, almost no OS install utilities allow you to specify the UID/GID of the default user that's created during setup, which means we have to do this afterward, thus this tutorial exists to give me and everyone a clear path to UID consistency.

Linux

I almost always run Debian on my Linux machines, thus I can't say this is the right way of doing it in other distros, I can't see why it wouldn't apply to others as well.

# Ensure no processes are running from the old user.
pkill -U $OLD_UID
 
# Change UID/GID using usermod.
usermod -u $NEW_UID -g $NEW_GID $USERNAME
 
# Fix file permissions to use the new UID.
find / -uid $OLD_UID -exec chown -h $NEW_UID {} +
find / -gid $OLD_UID -exec chgrp -h $NEW_GID {} +

If you're using a Raspberry Pi with its graphical desktop environment, you should use raspi-config to disable booting straight to X.

fix-unix-perms

Anonymous (anonymous@undisclosed.example.com) — 2023-10-09T15:53:52+00:00

Fixing UNIX Permissions

Recently, because of a long due migration from Windows file servers and separate Linux file servers to a single multi-drive-bay server chassis running multiple FreeBSD VMs we had to deal with a bunch of permission issues. The best way to solve these was to run the following commands:

find . -type d -not -path "./.snap" -exec chmod 775 {} \;
find . -type f -not -path "./.snap/*" -exec chmod 664 {} \;

These take care to ignore the .snap snapshot directory that's created by FreeBSD, otherwise, you'll have issues down the line.

Also, if you want to ensure that the entire filesystem respects the default layout for shared files where directories are 775 and files are 664. If you also require a change in owner or group you can also run the following commands:

find . -type d -not -path "./.snap" -exec chown nathanpc:staff {} \;
find . -type f -not -path "./.snap/*" -exec chown nathanpc:staff {} \;

Common Conventions