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From: | Peng Yu |
Subject: | How to test if stdin is empty, if not empty print to stdout, otherwise do something else. |
Date: | Tue, 24 Mar 2020 18:43:49 -0500 |
Hi, ifne from moreutils can work similar to this goal. But it is an external program. I'd like to test if stdin is not empty, then print to stdout of the input. But the following code is not robust for this goal. Is there a robust way to do so in bash? Thanks. $ function f { if read -n1; then echo "$REPLY" cat else echo 'No input from stdin' fi } $ { echo; seq 3; } | f 1 2 3 $ seq 10 13 | f 1 0 11 12 13 $ f < /dev/null No input from stdin -- Regards, Peng
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