Redirect stdout to file and tee stderr to the same file

Question

I am running a command which will (very likely) output text to both stderr and stdout. I want to save both stderr and stdout to the same file, but I only want stderr printing to the terminal.

How can I get this to work? I've tried mycommand 1>&2 | tee file.txt >/dev/null mycommand 1>&2 | tee file.txt >/dev/null but that doesn't print anything to the terminal.

Answer 1

If You Don't Need Perfect Ordering

Using two separate copies of tee , both writing to the same file in append mode but only one of them subsequently forwarding content to /dev/null , will get you where you need to be:

mycommand \
  2> >(tee -a file.txt >&2) \
   > >(tee -a file.txt >/dev/null)

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If You Do Need Perfect Ordering

See Separately redirecting and recombining stderr/stdout without losing ordering