Date: Sun, 20 Sep 2020 23:26:55 +0530 From: Manish Jain <bourne.identity@hotmail.com> To: Polytropon <freebsd@edvax.de>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Error message output Message-ID: <DB8PR06MB64420EDA7DE039284833F648F63D0@DB8PR06MB6442.eurprd06.prod.outlook.com> In-Reply-To: <20200920191108.22864e5c.freebsd@edvax.de> References: <20200920191108.22864e5c.freebsd@edvax.de>
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On 2020-09-20 22:41, Polytropon wrote:
> 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?
>
>
Fully valid. Whenever I write any C code, those are the guidelines I
adhere to myself.
Regards,
Manish Jain
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