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Calculate the average execution time (of short running scripts) with awk

 $ for i in {1..10}; do time some_script.sh; done 2>&1 | grep ^real | sed -e s/.*m// | awk '{sum += $1} END {print sum / NR}'

— by Janos on Dec. 21, 2011, 8:50 a.m.

Explanation

  • The for loop runs some_script.sh 10 times, measuring its execution time with time
  • The stderr of the for loop is redirected to stdout, this is to capture the output of time so we can grep it
  • grep ^real is to get only the lines starting with "real" in the output of time
  • sed is to delete the beginning of the line up to minutes part (in the output of time)
  • For each line, awk adds to the sum, so that in the end it can output the average, which is the total sum, divided by the number of input records (= NR)

Limitations

The snippet assumes that the running time of some_script.sh is less than 1 minute, otherwise it won't work at all. Depending on your system, the time builtin might work differently. Another alternative is to use the time command /usr/bin/time instead of the bash builtin.