0

I stumbled across this link: "watch" the output of a command until a particular string is observed and then exit

I know the PID of the process. I want to log the process "resource-consumption" using top.

Basically top -p PID -b >> LOGFILE.

I want to have this run in increments, say every 5 seconds using the "watch" command

watch -n 5

From an independent/external program, I will append "We Are Finished" to the logfile.

I want the logging of watch/top to break/exit when "We are Finished" So grep should be evaluating the entire log file, not just the current value.

I want the command to run in a nonblocking form... maybe ends with " & "

I set -d to 5 so top and watch are creating at the same time? ...

Here is my attempt using the "-e" option suggested from the link above, not working as expected... PID and LOGFILE are appropriate values.

watch -n 5 -e "!  top -d 5 -b -p PID >> LOGFILE | grep -m 1 \"We Are Finished\"" &
Community
  • 1
mshaffer
  • 103
  • If you append standard output to LOGFILE, then nothing is piped to grep. You need to pipe through tee -a LOGFILE to direct output to both places, or (more complex) make grep take its input from LOGFILE after it has been written. – AFH Jan 26 '17 at 16:05
  • @afh thanks for the ideas... can you provide the tee syntax? I do not need "more complex" since "We are Finished" is not being written by this watch loop. – mshaffer Jan 26 '17 at 16:11
  • watch -n 5 -e "! top -d 5 -b -p PID >> LOGFILE | grep -m 1 "We Are Finished" LOGFILE " & – mshaffer Jan 26 '17 at 16:12
  • I don't understand your comments: you have just reiterated your original command with an erroneous extra double-quote. I gave you the syntax in my comment above: replace >> LOGFILE with | tee -a LOGFILE, but if "We are Finished" is not being written why are you looking for it? – AFH Jan 26 '17 at 16:26
  • @AFH "We are Finished" is being written by an external program... The external program executes this "logging" feature.... and the logging feature stops itself on "We are Finished" – mshaffer Jan 26 '17 at 16:30
  • This is why I added "LOGFILE" twice. once on the grep side... – mshaffer Jan 26 '17 at 16:31
  • 1
    Sorry, I didn't notice it on the end. You should use && instead of | before grep. The reason I said this was more complex is that "We are Finished" may be in LOGFILE before the command is run, whereas tee detects the string in each run of the command only. – AFH Jan 26 '17 at 16:45

1 Answers1

0
until grep -qm 1 '\"We Are Finished\"' LOGFILE; do top -d 5 -n 12 -b -p PID >> LOGFILE; done

If you want to exit the logging on a process when the pid is no longer running the script below should work? (this avoids two processes writing to same file?)

It takes three parameters: the PID, the location of LOGFILE and the TIME between log entries.

#!/bin/bash

if [ $# -lt 3 ]
  then
    echo "Usage logpid (PID) (LOGFILE) (Time between in sec)"
    exit 1;
fi

while :
    do 
    if  ps -p $1 > /dev/null ; then
    top -n 1 -b -p $1 >> $2;
    else
    echo "Exited No pid";
    break;
    fi
    sleep $3;   
done
Toby Speight
  • 4,967
MShaffer
  • 146