Redirects

Tired of figuring out how to redirect output and capture the values accordingly? This is definitely the recipe.

All to Stderr

Use 1>&2 at the beginning of the command:

1>&2 echo "all goes into stderr, even for stdout"

All to Stdout

Use 2>&1 at the beginning of the command:

2>&1 echo "all goes into stderr, even for stdout"

Silent Stderr, Capture only Stdout

Use 2> at the end and redirect to /dev/null:

ret="$(echo "all goes into stderr, even for stdout" 2> /dev/null)"

Silent Stdout, Capture only Stderr

Use 2>&1 and then redirect the stdout to /dev/null:

ret="$(2>&1 echo "all goes into stderr, even for stdout" > /dev/null)"

Silent Everything

Use &> to /dev/null:

echo "all goes into stderr, even for stdout" &> /dev/null

Split Capture

Use > and 2> to the desired output files. The former is the stdout, the latter is stderr (the one with 2):

echo "all goes into stderr, even for stdout" > ./stdout.log 2> ./stderr.log

That's all about shell output redirects.