Shell Programming and Scripting

hi all,

i need to measure time difference between the time a process started, to the time it ended. i am assuming the following are the steps:

1. output 'date' command at start time
2. output 'date' command at end time
3. subtract the two

question is, how do i subtract the two time outputs, when that output looks like: "Wed Oct 20 06:20:22 UTC 2010" as an example.

So basically, I need the result of the subtraction to look something like: 1h 22m 09s.

Appreciate any assistance I can get.
Thanks!

Which shell are you running? Date manipulation is not the easiest thing to do in Unix. There have been multiple posts on this within these forums.
Check this. It's a very useful post on everything related to date

Meanwhile if you have the GNU version of 'date' you could just run:

Code:

date +%s

This outputs seconds since `00:00:00 1970-01-01 UTC' (a GNU extension).
Thus you would end up getting date as 1287584703, etc. This is easy to store and subtract.

Which system do you process?

Maybe you must use time command

simply ex

Code:

# time ps -ef 1>/dev/null
real    0m0.038s
user    0m0.005s
sys     0m0.033s

thanks for the responses.
follow up question: how do you get the "1287584703" back to a format like "1h 22m 09s"
thanks!

See my comment in this thread (very similar request to yours).

https://www.unix.com/shell-programmin...e-process.html