Beware the Evil Bash Script: How Malicious Aliases Can Hijack Your Shell

Warning: Do not run this script in a production environment. The script is a Bash shell prank that redefines many aliases, functions, and environment variables, turning a normal shell into a chaotic playground.

Terrible Default Editor

The EDITOR variable is set to rm instead of vi, emacs or nano. Any program that invokes the default editor (e.g., crontab -e) will delete files.

EDITOR is used by system utilities to launch the default editor.

Devious Tab Key

The Tab key is redefined as a backspace, causing characters to be erased when you try to autocomplete.

tset -e sets the erase character to backspace.

Mysterious Exit

Enabling set -e (or set -o errexit) makes the shell exit on any non‑zero command status, leading to unexpected termination.

Cat Becomes True

The cat command is aliased to true, which always returns exit status 0 and produces no output, making file inspection impossible.

Unpredictable ls Order

The ls command is overridden, so its output appears in random order. Options like -f, -r, -S, -t, -u control sorting, but the script disables them.

Directory Vanishing

Aliases such as rm -rf -v are used to delete directories silently, making it seem as if cd fails because the directory no longer exists.

sudo Triggers Shutdown

Running any command with sudo invokes shutdown -P now, instantly powering off the machine and broadcasting the attempted command.

Fork Bomb via clear

The clear command is aliased to a minimal fork bomb, exhausting system resources and freezing the machine.

Random Future Dates

Using date with $RANDOM returns dates far in the future, adding to the confusion.

CD and grep Tricks

Aliases make cd ineffective and grep -n output unpredictable line numbers.

Reversed Logic

Conditions in if, for, and while are negated with !, causing logic to behave opposite to expectations.

Key Binding Chaos

The bind command remaps Enter (CTRL‑J) to backspace, so pressing Enter deletes characters.

Yes Command Hijacked

The yes command is redefined, breaking scripts that rely on automatic affirmative responses.

Vim Becomes Inert

Aliasing vim with +q makes the editor exit immediately without opening files.

Final Remedy

All these mischiefs stem from malicious alias definitions. To restore normal behavior, remove or unalias the offending entries, or invoke commands via their absolute paths.

For a full example, see the original script at https://github.com/mathiasbynens/evil.sh/blob/master/evil.sh and source it in .bash_profile only if you truly intend to prank a colleague.