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Top Forums UNIX for Dummies Questions & Answers How do you wait for command substitution processes to complete? Post 302397993 by mrvwman on Tuesday 23rd of February 2010 02:23:10 PM
Old 02-23-2010
wait & sleep

wait doesn't work, I tried that. sleep might work most of the time, but it isn't a guarantee that the work would be done after sleeping.

I wrote up the following to do what I want, it works but I guess I was hoping for a more elegant solution like a simple flag for wait or something.

Code:
#!/bin/bash

DONE_PIPE=/tmp/donepipe$$
mkfifo $DONE_PIPE
exec 7<>$DONE_PIPE

zcat /logs/billing.log.2009/09/01/billing.log.20090901_101924.96.17.157.45.gz | tee >(wc && echo "HELLO" && echo "DONE" >&7) > /dev/null
COUNTER=0
#wait for the processors to complete
while [ $COUNTER -lt 1 ]; do
    read LINE <&7
    echo $LINE
    let COUNTER=COUNTER+1
done

exec 7>&-
exec 7<&-

rm $DONE_PIPE

echo "WORLD"

Which produces the following output:
Code:
22245  175374 3598423
HELLO
DONE
WORLD

With the above code multiple >(cmd) arguments can be given to tee and each would echo a statement to the 7 filedescriptor when they're complete. The while loop condition would just be adjusted to wait for however many processes you have launched using >(cmd).
 

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BPING(1)							  BP executables							  BPING(1)

NAME
bping - Send and receive Bundle Protocol echo bundles. SYNOPSIS
bping [-c count] [-i interval] [-p priority] [-q wait] [-r flags] [-t ttl] srcEID destEID [reporttoEID] DESCRIPTION
bping sends bundles from srcEID to destEID. If the destEID echoes the bundles back (for instance, it is a bpecho endpoint), bping will print the round-trip time. When complete, bping will print statistics before exiting. It is very similar to ping, except it works with the bundle protocol. bping terminates when one of the following happens: it receives the SIGINT signal (Ctrl+C), it receives responses to all of the bundles it sent, or it has sent all count of its bundles and waited wait seconds. EXIT STATUS
These exit statuses are taken from ping. 0 bping has terminated normally, and received responses to all the packets it sent. 1 bping has terminated normally, but it did not receive responses to all the packets it sent. 2 bping has terminated due to an error. Details should be noted in the ion.log log file. FILES
No configuration files are needed. ENVIRONMENT
No environment variables apply. DIAGNOSTICS
Diagnostic messages produced by bping are written to the ION log file ion.log and printed to standard error. Diagnostic messages that don't cause bping to terminate indicate a failure parsing an echo response bundle. This means that destEID isn't an echo endpoint: it's responding with some other bundle message of an unexpected format. Can't attach to BP. bpadmin has not yet initialized Bundle Protocol operations. Can't open own endpoint. Another application has already opened ownEndpointId. Terminate that application and rerun. bping bundle reception failed. BP system error. Check for earlier diagnostic messages describing the cause of the error; correct problem and rerun. No space for ZCO extent. ION system error. Check for earlier diagnostic messages describing the cause of the error; correct problem and rerun. Can't create ZCO. ION system error. Check for earlier diagnostic messages describing the cause of the error; correct problem and rerun. bping can't send echo bundle. BP system error. Check for earlier diagnostic messages describing the cause of the error; correct problem and rerun. BUGS
Report bugs to <ion-bugs@korgano.eecs.ohiou.edu> SEE ALSO
bpecho(1), bptrace(1), bpadmin(1), bp(3), ping(8) perl v5.14.2 2012-05-25 BPING(1)
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