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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
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Wait for an already launched program to stop before starting a new command.

Terminal - Wait for an already launched program to stop before starting a new command.
2010-01-15 04:03:11
User: bhepple
Functions: wait
Wait for an already launched program to stop before starting a new command.

If you really _must_ use a loop, this is better than parsing the output of 'ps':

PID=$! ;while kill -0 $PID &>/dev/null; do sleep 1; done

kill -0 $PID returns 0 if the process still exists; otherwise 1


There are 3 alternatives - vote for the best!

Terminal - Alternatives
wait $!
2010-06-07 21:56:36
User: noahspurrier
Functions: wait

Referring to the original post, if you are using $! then that means the process is a child of the current shell, so you can just use `wait $!`. If you are trying to wait for a process created outside of the current shell, then the loop on `kill -0 $PID` is good; although, you can't get the exit status of the process.

while (ps -ef | grep [r]unning_program_name); do sleep 10; done; command_to_execute
2010-01-14 16:26:34
User: m_a_xim
Functions: grep ps sleep

The '[r]' is to avoid grep from grepping itself. (interchange 'r' by the appropriate letter)

Here is an example that I use a lot (as root or halt will not work):

while (ps -ef | grep [w]get); do sleep 10; done; sleep 60; halt

I add the 'sleep 60' command just in case something went wrong; so that I have time to cancel.

Very useful if you are going to bed while downloading something and do not want your computer running all night.

Know a better way?

If you can do better, submit your command here.

What others think

'wait' only works when the program is a child process of the working terminal.

Comment by m_a_xim 352 weeks ago

Yeah - the original poster was pretty vague on te setup.

Comment by bhepple 351 weeks and 6 days ago

Your point of view

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