Re: A suggestion to add to gnu ed: command line option to start on line foo or bar.

[Antonio Diaz Diaz]

John Cowan wrote:
> I agree that ed should perhaps behave differently in the interactive and
> > scripted cases, but I think we can use the existing option '-l,
> > --loose-exit-status' to ignore a mismatch in the interactive case instead
> > of using a new option to force an error in the scripted case.
>
> Per contra, the point of the proposed -e option is to force an immediate
> exit on error.

Ooops! I forgot to test for interactive mode and made -l avoid the immediate 
exit on error also in scripted mode.

I have just uploaded ed-1.20-pre2 which in case of mismatch fails 
immediately with exit status 1 unless -l is specified and mode is interactive.

> For example, suppose we want to edit a file using a script
> that removes all except certain lines (using the 'v' command) and then
> writes out the file.  But if there are no such lines, it is not the right
> file.
>
> This situation will cause ed to return an error message and code, but the
> file (now empty) will still be written out, which is a Very Bad Thing.  The
> proposed -e option will abort ed as soon as the search fails rather than
> carrying on to the end of the script and only then returning an error.  The
> same would be the case if the purpose of the script was to delete lines
> 100-200 and there were no such lines.

I see. When you said "-e ... causes termination with error status 1 when 
*any* error is detected" you meant "any error also in the script, not only 
in the new '+' option". But ed already exits immediately with non-zero 
status when any error is found and stdin is a regular file. Is this not enough?