Custom format for time command

You could use the date command to get the current time before and after performing the work to be timed and calculate the difference like this:

#!/bin/bash# Get time as a UNIX timestamp (seconds elapsed since Jan 1, 1970 0:00 UTC)T="$(date +%s)"# Do some work heresleep 2T="$(($(date +%s)-T))"echo "Time in seconds: ${T}"printf "Pretty format: %02d:%02d:%02d:%02d\n" "$((T/86400))" "$((T/3600%24))" "$((T/60%60))" "$((T%60))""

Notes:$((...)) can be used for basic arithmetic in bash – caution: do not put spaces before a minus - as this might be interpreted as a command-line option.

See also: http://tldp.org/LDP/abs/html/arithexp.html

EDIT:
Additionally, you may want to take a look at sed to search and extract substrings from the output generated by time.

EDIT:

Example for timing with milliseconds (actually nanoseconds but truncated to milliseconds here). Your version of date has to support the %N format and bash should support large numbers.

# UNIX timestamp concatenated with nanosecondsT="$(date +%s%N)"# Do some work heresleep 2# Time interval in nanosecondsT="$(($(date +%s%N)-T))"# SecondsS="$((T/1000000000))"# MillisecondsM="$((T/1000000))"echo "Time in nanoseconds: ${T}"printf "Pretty format: %02d:%02d:%02d:%02d.%03d\n" "$((S/86400))" "$((S/3600%24))" "$((S/60%60))" "$((S%60))" "${M}"

DISCLAIMER:
My original version said

M="$((T%1000000000/1000000))"

but this was edited out because it apparently did not work for some people whereas the new version reportedly did. I did not approve of this because I think that you have to use the remainder only but was outvoted.
Choose whatever fits you.

To use the Bash builtin time rather than /bin/time you can set this variable:

TIMEFORMAT='%3R'

which will output the real time that looks like this:

5.009

or

65.233

The number specifies the precision and can range from 0 to 3 (the default).

You can use:

TIMEFORMAT='%3lR'

to get output that looks like:

3m10.022s

The l (ell) gives a long format.

From the man page for time:

1. There may be a shell built-in called time, avoid this by specifying /usr/bin/time

2. You can provide a format string and one of the format options is elapsed time - e.g. %E

   /usr/bin/time -f'%E' $CMD

Example:

$ /usr/bin/time -f'%E' ls /tmp/mako/res.py  res.pyc0:00.01