How to Calculate Script Run Time [Duplicate]

Question

Consider this shell redirect: telnet towel.blinkenlights.nl >> starWarz when it ends, the session will break, detach from host or something like that. I want to know how long the connection lasts. How might I determine this?

Accepted Answer

Sounds like you're looking for the time builtin:

$ help time
time: time [-p] pipeline
    Report time consumed by pipeline's execution.

    Execute PIPELINE and print a summary of the real time, user CPU time,
    and system CPU time spent executing PIPELINE when it terminates.

    Options:
      -p    print the timing summary in the portable Posix format

    The value of the TIMEFORMAT variable is used as the output format.

    Exit Status:
    The return status is the return status of PIPELINE.

It will print a report of the time taken by a command. For example:

$ time sleep 3

real    0m3.027s
user    0m0.000s
sys     0m0.000s

The "real" field is the actual time that passes, the same value you would have measured with a watch. So, you can simply do:

time telnet towel.blinkenlights.nl >> starWarz

Accepted Answer

Most of the shells has a builtin named time, bash has it too. It will show you the actual human time (real) a process takes with the CPU time the process spends on user space (user) and kernel space (sys).

So run the command perpending time:

time telnet towel.blinkenlights.nl >> starWar

At the end bash will show the time on STDERR like:

real    XmX.XXXs
user    YmY.YYYs
sys     ZmZ.ZZZs

Even if you are on a shell that does not have the time builtin you have the external time command /usr/bin/time from the time package. The usage is same.

How to Calculate Script Run Time [Duplicate]

Must Read

2 Answers

David Miller