Write STDERR To A File Instead Of A Terminal

TL;DR

some_command &> output.txt

That line runs a command and sends both STDOUT and STDERR to the "output.txt" file.

The command works in some shells (e.g. bash and zsh) but not others (e.g. sh and ksh). If it doesn't work, try:

command > output.txt 2>&1

(There can't be a space between the > and & characters)
Sending STDOUT to one file and STDERR to another is done with:

command > output.txt 2> error.txt

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