Используйтеhttps://github.com/acbits/semaдля использования семафоров в сценариях оболочки.
A.sh
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#!/bin/sh
echo A.sh started
sema -c S1
./B.sh &
echo A.sh more work
echo waiting for B.sh to finish
sema -w S1
echo B.sh finished execution
echo A.sh do more work
# cleanup semaphores
sema -d S1
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B.sh
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#!/bin/sh
echo Hello from B.sh
sleep 5
sema -r S1
echo Bye bye from B.sh
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