Re: Warn when editing read-only files

[Antonio Diaz Diaz]

Dan Jacobson wrote:
> Because ed does not warn when editing other peoples' files,
> when it comes time to save the file, one might realize there is nowhere
> to save it!

How do you propose to implement such a warning while remaining 
POSIX-compliant? (See 'Edit Command' at 
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/ed.html).

Some people may find disrupting that something like "Read-only file" is 
printed to stderr, and even more disrupting if it is printed to stdout.

John Cowan wrote:
> It would be nice if ed understood ~ in pathnames, however.

This should be doable, as ed already uses HOME to save ed.hup in the user's 
home directory. Also, POSIX seems to say nothing against (or about) 
expanding '~' to $HOME in file names like '~/foo'.

Antonio.