In a bash script, I would like to capture the standard output of a long command line by line, so that they can be analysed and reported while initial command is still running. This is the complicated way I can imagine of doing it:
# Start long command in a separated process and redirect stdout to temp file longcommand > /tmp/tmp$$.out & #loop until process completes ps cax | grep longcommand > /dev/null while [ $? -eq 0 ] do #capture the last lines in temp file and determine if there is new content to analyse tail /tmp/tmp$$.out # ... sleep 1 s # sleep in order not to clog cpu ps cax | grep longcommand > /dev/null done
I would like to know if there is a simpler way of doing so.
In order to clarify my question, I will add this. The
longcommanddisplays its status line by line once per second. I would like to catch the output before the
This way, I can potentially kill the
longcommand if it does not provide the results I expect.
I have tried:
longcommand | while IFS= read -r line do whatever "$line" done
echo) only executes after