I can exit a program on error like so
ls /fake/folder || exit 1
I can redirect the output to a file and STDOUT like so
ls /usr/bin | tee foo.txt
But I can't do
ls /fake/folder | tee foo.txt || exit 1
because I get the output of tee and not ls
How do I redirect the output to both a file and STDOUT and exit on error
This is exactly what the pipefail runtime option is meant for:
# Make a pipeline successful only if **all** components are successful
set -o pipefail
ls /fake/folder | tee foo.txt || exit 1
If you want to be explicit about precedence, by the way, consider:
set -o pipefail
{ ls /fake/folder | tee foo.txt; } || exit 1 # same thing, but maybe more clear
...or, if you want to avoid making runtime configuration changes, you can use PIPESTATUS to check the exit status of any individual element of the most recent pipeline:
ls /fake/folder | tee foo.txt
(( ${PIPESTATUS[0]} == 0 )) || exit
If you don't want to take any of the approaches above, but are willing to use ksh extensions adopted by bash, putting it in a process substitution rather than a pipeline will prevent tee from impacting exit status:
ls /fake/folder > >(tee foo.txt) || exit 1
