Bugfix for `sed` error messages

[atreyasha]

Checklist

• Admin:
  • [x] No duplicate PRs
• Integration:
  • [x] Update unit tests
  • [x] Update shell completions
  • [x] Update configuration file
• Documentation:
  • [x] Update usage function
  • [x] Update mandoc
  • [x] Update readme
  • [x] Update locales
• Release:
  • [x] Update change log
  • [x] Update DOWNGRADE_VERSION

Description

This PR addresses #184 by directing stderr from all sed commands to /dev/null.

I considered wrapping the blocks/pipes where sed is used with an if-statement that checks for their exit codes as per https://github.com/pbrisbin/downgrade/issues/184#issuecomment-1053652095. But given there are several such blocks with sed, I thought it might be simpler to just direct the error message to /dev/null. The downside is that we don't get a special error message specifying invalid input, but we would still get the No results found error message which is not incorrect either.

WDYT?

[atreyasha]

I guess I'm just not clear on the behavior we're trying to fix. I think you're suggesting the current behavior is:

% downgrade whatever
sed error...
No results found
[exit 1]

Exactly, this is the current behaviour and I would like to ideally silence the sed error messages in such cases.

So I would suggest that we only change the sed that we know failed in that bug report, the one that we know fails because of an invalid search term. I think that would be the most minimal bugfix and a net improvement.

True. I looked deeper and found that the sed errors arise from the process_term function:

https://github.com/pbrisbin/downgrade/blob/4c3af2cfee79f2c4265abe69961fa1cc2dca2f4b/downgrade#L322-L326

Somehow despite the inner sed commands from process_term returning exit-code 1, the process_term function still continues to completion. This stops when I remove the if-block around process_term.

As more comprehensive alternative, we could introduce something like this:

sed_msg() {
 local msg=$1
 shift

 if ! sed "$@"; then
   echo "Failed $msg" >&2
   exit 1
 fi
}

Works like a charm. Modified the PR.

WDYT?

[atreyasha]

Yes, done