Re: How to make "division by zero attempted" error message more informative?

[Ed Morton]

I think you're thinking about this the wrong way. If you had a command 
like `grep 'foo' file` that you call from multiple bash scripts you 
wouldn't ask the grep developers to add some way to a prefix to the 
error message that the users can control and then the same for sed, cat, 
sort, and every other command. Instead you could write your code as:

   grep 'foo' file || printf '%s[%d]: failure.\n' "$0" "$LINENO" >&2

so just do the same thing with awk:

   $ cat ./tst.sh
   #!/usr/bin/env bash

   awk -e '{ print 10/$1 }' <<< 0 || printf '%s[%d]: failure.\n' "$0"
   "$LINENO" >&2

   $ ./tst.sh
   awk: cmd. line:1: (FILENAME=- FNR=1) fatal: division by zero attempted
   ./tst.sh[3]: failure.

That extra line tells you the problem was at line 3 of tst.sh. Obviously 
you can write a function to call in the `|| ...` leg instead of 
duplicating that code everywhere. Google for examples of that.

Regards,

    Ed

On 3/3/2022 12:09 PM, Peng Yu wrote:
> Sorry. I accidentally sent the email to the bug mailing list. It
> should be sent to the help mailing list.
>
>
> On 3/3/22, Ed Morton<mortoneccc@comcast.net>  wrote:
> > That error message tells you the line number in the script (`line:1`),
> > the input file name (`FILENAME=-`), and the line number in the input
> > file where the error occurred (`FNR=1`) as well as telling you it's a
> > divide by zero and you can clearly see in your code where you're
> > dividing so I'm not sure what more information could be needed/provided.
> The problem is that if this piece code is embedded inline in many bash
> scripts, it will be very hard to find where the error is from.
>
> > Out of curiosity though - what would you like the error message to say?
> Maybe there can be a prefix to the error message that the users can control?
>
> >       Ed.
> >
> > On 3/3/2022 6:46 AM, Peng Yu wrote:
> > > I see something like this. But when this kind of command is called at
> > > multiple scripts. It is hard to tell where the error is from.
> > >
> > > $ awk -e '{ print 10/$1 }' <<< 0
> > > awk: cmd. line:1: (FILENAME=- FNR=1) fatal: division by zero attempted
> > >
> > > Is there a way to customize the error message so that I can know where
> > > the
> > > error is coming from? Thanks.