How to output the real time a command takes (and nothing else)?

Question

How can I output the real time a command takes (and nothing else)?

Example:

This won't work:

$ time -p sleep 2 | grep real
real 2.00
user 0.00
sys 0.00

I want something like:

$ print-real-time sleep 2
2.00

Answer 1

You need to capture the output of time first. Then you can process it.

Answer 2

A non-BASH-specific solution (explicitly use /usr/bin/time so it's not the pipe-gobbling bash builtin) --

/usr/bin/time -p some_command_or_subshell 2>&1 | grep real | awk '{print $2}'

Depending on the delicate nature of whatever you feed this output to you may want to redirect the output of your subject command to /dev/null...

Answer 3

Here's a hacky solution using cut to split the fields.

time -p sleep 2 | grep real | cut -f2 -d' '

You can also use awk:

time -p sleep 2 | grep real | awk '{ print $2 }'