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Why does running time and /usr/bin/time give different results?


thomas@tbdesktop:~$ /usr/bin/time -f "Elapsed time:%E" wc /etc/hosts
  9  25 224 /etc/hosts
Elapsed time:0:00.04


thomas@tbdesktop:~$ time -f "Elapsed time:%E" wc /etc/hosts
-f: command not found

real    0m0.079s
user    0m0.052s
sys 0m0.024s

My path is as follows. As far as I can see, there is only one time executable in the path.

thomas@tbdesktop:~$ echo $PATH
thomas@tbdesktop:~$ find / -name time 2> /dev/null
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1 Answer 1

up vote 3 down vote accepted

Because time and /usr/bin/time run different code. In order to determine it, do the following:

type time

It will show you that:

time is a shell keyword

Thus, it doesn't run /usr/bin/time if you simply call time.

They are different things...

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Great answer - thanks :) – Thomas Bratt Oct 2 '12 at 14:16

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