CODEWITHSUNDEEP
javashellpipe
S Kr
S Kr

Reputation: 1840

Getting the pid of a process present at the start of pipe

I have a shell script that runs a Java process p1 and also there's a non-Java process p2 that takes input from p1.

How can I get process id of p1?

I have a shell script that works unpredictably (sometimes it works, sometimes it doesn't). I have browsed the net but none of the answers seem perfect.

My script: 

nohup sh -c "exec java p1 | p2 2>&1" &
$pid=`echo $!`
my_pid=exec ps -eo "%p %c %P" | awk -v p=$pid 'p==$3{print $1 $2}' | grep java | sed -e 's/java//'

echo "my_pid $my_pid"

Upvotes: 0

Views: 644

Answers (1)

Tom Anderson
Tom Anderson

Reputation: 47233

This is a simplified version of mmd's answer from the question i linked to:

{ java p1 & echo $! >&2; } | p2 2>&1 &

This prints the PID of p1 on standard error. You also get a message from the shell telling you that the echo command has finished, but you can ignore that.

Upvotes: 2

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