chore: build scripts use sed -E for cross-OS compatibility

[alex-courtis]

Many thanks to @Uanela for finding this one: #3261 (comment)

I'd be really grateful for your testing with the "standard" macos sed.

[v3ceban]

Oh, I had a lot of "fun" with this as well in the past! GNU and BSD (default macOS) sed are slightly different, particularly around the -i flag (GNU: sed -i, BSD: sed -i '') and how the r command behaves inside brace groups and with multiple -e expressions. The person here summarized the differences well. Below are a couple of workarounds that I found with a simple example from the help-defaults.sh:

---

Current usage:

sed -i -e "/${inject}/r /tmp/DEFAULT_OPTS.6.lua" -e "/${inject}/d" "${WIP}"

Workarounds:

1. Avoid using -i flag entirely and do a two-stage pipe to first filter, then delete, then replace:

# NOTE: POSIX `r` command reads the filename until end of line,
# so a newline is required after the filename to terminate it.
# GNU sed treats the end of the -e string as a line boundary, so it works, but technically it's not POSIX compliant.
sed "/${inject}/r /tmp/DEFAULT_OPTS.6.lua
" "${WIP}" | sed "/${inject}/d" > "${WIP}.tmp" && mv "${WIP}.tmp" "${WIP}"

2. Maintain two variants of the command and use the correct one for the given OS:

if [ "$(uname -s)" = "Darwin" ]; then
  sed -i '' "/${inject}/r /tmp/DEFAULT_OPTS.6.lua
  " "${WIP}"
  sed -i '' "/${inject}/d" "${WIP}"
else
  sed -i -e "/${inject}/r /tmp/DEFAULT_OPTS.6.lua" -e "/${inject}/d" "${WIP}"
fi

3. Replace sed with POSIX awk, which should behave the same on both systems:

awk "/${inject}/{while((getline line < \"/tmp/DEFAULT_OPTS.6.lua\") > 0) print line; next} {print}" "${WIP}" > "${WIP}.tmp" && mv "${WIP}.tmp" "${WIP}"

4. Require macOS users to install gsed and run the scripts with it on PATH:

PATH="$HOMEBREW_PREFIX/opt/gnu-sed/libexec/gnubin:$PATH" make help-update

or conditionally call gsed instead of sed based on user's OS (similar to the second workaround).

[Uanela]

@alex-courtis I will test this one shortly

[alex-courtis]

Below are a couple of workarounds that I found with a simple example from the help-defaults.sh:

Nice one @v3ceban , many solutions there.

1 is clear and simple. Using -i is not really necessary and is fragile and confusing.

3 is pragmatic, simple, compatible and there is precedent with doc-comments.sh

2 and 4 aren't very friendly and create friction.

Let's see how it tests.