It Happened: Steam Does the "rm -rf /*" on Linux

In 2015, Steam accidentally deleted all of a user's files on Linux due to a bug in a Bash script.

Why It Happened?

Moved ~/.local/share/steam. Ran steam. It deleted everything on system owned by user.

rm -rf "$STEAMROOT/"* could be evaluated as rm -rf "/"* if $STEAMROOT is empty

https://github.com/ValveSoftware/steam-for-linux/issues/3671#issuecomment-70159084 (accessed 2025-02-19)

The cause of the issue seemed to be in the way the zeroth argument passed by the shell was handled.

I believe the issue starts on line 19:

# figure out the absolute path to the script being run a bit
# non-obvious, the ${0%/*} pulls the path out of $0, cd's into the
# specified directory, then uses $PWD to figure out where that
# directory lives - and all this in a subshell, so we don't affect
# $PWD

STEAMROOT="$(cd "${0%/*}" && echo $PWD)"
STEAMDATA="$STEAMROOT"

This probably returns as empty which mean: rm -rf "$STEAMROOT/"* is the same ass rm -rf "/"*.

https://github.com/ValveSoftware/steam-for-linux/issues/3671#issuecomment-70161790 (accessed 2025-03-06)

Essentially, what has happened was that they wrote rm -rf "${0%/*}/*" to delete all files in the directory where a program was installed. If $0 (the zeroth argument) was /folder/program, then "${0%/*}" would evaluate to /folder. However, if $0 was just program, then "${0%/*}" would be an empty string "" , which means rm -rf "${0%/*}/*" evaluates to rm -rf /*, and that's how all files get deleted.

• What Values can the Zeroth Argument Have? (in the Command-Line)