Can i use time A | B to measure the time taken to run A | B?

Question

I imagine time A | B would only measure the time taken to run A (since the argument to time is A). What's the solution ?

score 1 · Answer 1 · edited Jul 11 '17 at 23:43

1

Depends on the shell. e.g. Bash has a keyword time that times the whole pipeline. An external implementation of time would only time A in your example. A workaround might be to explicitly run an extra shell:

time sh -c "A | B"

edited Jul 11 '17 at 23:43

Gilles 'SO- stop being evil'

829,060

answered Jul 10 '17 at 11:08

ilkkachu

138,973

Technically time is not a builtin, but a keyword (in bash, and in ksh and zsh which have the same feature). It has to be so that time applies to the following compound command and not just to a simple command. – Gilles 'SO- stop being evil' Jul 11 '17 at 23:42

Basile Starynkevitch · Answer 2 · 2017-07-10T12:03:13.600

0

You could also use a subshell, e.g.

 time ( A | B )

at least when time is the bash builtin (but then a subshell is useless). If you want to use the time(1) command (see this) you'll better explicitly run some sh -c like answered by iikkachu

edited Jul 10 '17 at 12:03

answered Jul 10 '17 at 11:24

Basile Starynkevitch

10,561

Can i use time A | B to measure the time taken to run A | B?

2 Answers2