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How to wait in a bash script for several subprocesses spawned from that script to finish, and then return exit code !=0 when any of the subprocesses ends with code !=0?
Simple script:
#!/bin/bash for i in `seq 0 9`; do doCalculations $i & done wait The above script will wait for all 10 spawned subprocesses, but it will always give exit status 0 (see help wait). How can I modify this script so it will discover exit statuses of spawned subprocesses and return exit code 1 when any of subprocesses ends with code !=0?
Is there any better solution for that than collecting PIDs of the subprocesses, wait for them in order and sum exit statuses?
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How to Use the Bash Sleep Command. Sleep is a very versatile command with a very simple syntax. It is as easy as typing sleep N . This will pause your script for N seconds, with N being either a positive integer or a floating point number.
The bash WAIT command is used to halt the execution of a script until all background jobs or specified JobID/PIDs terminate successfully and return an expected exit code to trigger the next command that was “waited for.”
A successful command returns a 0, while an unsuccessful one returns a non-zero value that usually can be interpreted as an error code. Well-behaved UNIX commands, programs, and utilities return a 0 exit code upon successful completion, though there are some exceptions.
bash [filename] runs the commands saved in a file. $@ refers to all of a shell script's command-line arguments. $1 , $2 , etc., refer to the first command-line argument, the second command-line argument, etc. Place variables in quotes if the values might have spaces in them.
wait also (optionally) takes the PID of the process to wait for, and with $! you get the PID of the last command launched in the background. Modify the loop to store the PID of each spawned sub-process into an array, and then loop again waiting on each PID.
# run processes and store pids in array for i in $n_procs; do ./procs[${i}] & pids[${i}]=$! done # wait for all pids for pid in ${pids[*]}; do wait $pid done If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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