Is there a way to find the running time of the last executed command in the shell?

bash, linux, macos, shell, unix

Solution

I do not know, how it is in bash, but in zsh you can define `preexec` and `precmd` functions so that they save the current time to variables `$STARTTIME` (preexec) and `$ENDTIME` (precmd) so you will be able to find the approximate running time. Or you can define an `accept-line` function so that it will prepend `time` before each command.

UPDATE: This is the code, which will store elapsed times in the `$_elapsed` array:

preexec () {
   (( $#_elapsed > 1000 )) && set -A _elapsed $_elapsed[-1000,-1]
   typeset -ig _start=SECONDS
}
precmd() { set -A _elapsed $_elapsed $(( SECONDS-_start )) }

Then if you run `sleep 10s`:

% set -A _elapsed # Clear the times
% sleep 10s
% sleep 2s ; echo $_elapsed[-1]
10
% echo $_elapsed
0 10 0

No need in four variables. No problems with names or additional delays. Just note that `$_elapsed` array may grow very big, so you need to delete the first items (this is done with the following piece of code: `(( $#_elapsed > 1000 )) && set -A _elapsed $_elapsed[-1000,-1]`).

UPDATE2: Found the script to support zsh-style precmd and preexec in bash. Maybe you will need to remove `typeset -ig` (I used just to force `$_start` to be integer) and replace `set -A var ...` with `var=( ... )` in order to get this working. And I do not know how to slice arrays and get their length in bash.

Script: http://www.twistedmatrix.com/users/glyph/preexec.bash.txt (web.archive)

UPDATE3: Found one problem: if you hit return with an empty line preexec does not run, while precmd does, so you will get meaningless values in `$_elapsed` array. In order to fix this replace the `precmd` function with the following code:

precmd () {
   (( _start >= 0 )) && set -A _elapsed $_elapsed $(( SECONDS-_start ))
   _start=-1 
}

Problem

Original source

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