diff command not working inside bash shell script

Question

I am trying to run

diff <(tar -tvf HIVE_CLIENT.tar.gz | sort) <(tar -tvf YARN_CLIENT.tar.gz | sort)

putting this command inside script, when I execute script it shows error

syntax error near unexpected token `(' "

But when I do not put inside script rather than run from shell directly it works.

Show shebang of your script and how do you run this script.

Cyrus
– Cyrus

2017-09-25 08:28:37 +00:00
Commented Sep 25, 2017 at 8:28 — Cyrus
– Cyrus, Commented Sep 25, 2017 at 8:28

nyronium · Accepted Answer · 2017-09-25 08:29:24Z

1

Probably your script is run with /bin/sh and not with /bin/bash, but command substitution is a bash feature and not implemented in sh. So I suppose you are using bash as your shell which is why it is working from the command line.

Try adding this prefix to your script, and remove existing shebangs (like #!/bin/sh or similar):

#!/bin/bash

answered Sep 25, 2017 at 8:29

nyronium

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P.... · Accepted Answer · 2017-09-25 10:26:36Z

You should try following two actions:

Use #!/bin/bash as your shebang (First line of your script)

This may be needed based on your bash, use only if opetion 1 does not help. Use following commands to flip between posix mode which is needed for process substitution:

set +o posix 
diff <(tar -tvf HIVE_CLIENT.tar.gz | sort) <(tar -tvf YARN_CLIENT.tar.gz | sort)
set -o posix

Example:

wc -l <(ls -lrt)
sh: syntax error near unexpected token `('

set +o posix  
wc -l <(ls -lrt)
114 /dev/fd/00

set -o posix
wc -l <(ls -lrt)
sh: syntax error near unexpected token `('

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