Date: Sun, 20 Sep 2020 19:11:08 +0200 From: Polytropon <freebsd@edvax.de> To: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Error message output Message-ID: <20200920191108.22864e5c.freebsd@edvax.de>
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I have a general question. Is it still considered useful to
output error messages of a script to standard error?
Example:
if [ something not okay ]; then
echo "the error message" > /dev/stderr
exit 1
fi
While progress messages will per default go to standard output,
error messages should be printed to standard error. The reason:
If a program is silenced to > /dev/null, error messages will
still be visible (no "silent failing"); if a user wants to
explicitely mute all messages, > /dev/null 2>&1 has to be
specified for the redirection. The judgement if a message is
a regular progress message, an information about some slightly
problematic case, or a real fatal error depends on the programmer.
For example:
echo "${FILE] processed, ${RECS} records counted."
-> standard output
echo "${DIR} already checked, skipping."
-> standard output (non-fatal error"
echo "${DEV} is read only, aborting."
exit 1
-> standard error (fatal error)
echo "Cannot start: Input filename missing."
usage()
exit 1
-> standard error (fatal error)
At least that's what I've learned centuries ago.
Is that still valid?
--
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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