remove reliance on platform specific commands in scripts

[tyler-french]

Some scripts and configuration won't build on a Mac with darwin OS because of the difference in certain commands like sed -i and case insensitivity.

Although not critical, we should clean these up to make it easier to iterate.

[stagnation]

Thanks for reporting. I do appreciate a command-based patching for simple stuff like those rather than to maintain patch files. But inadvertently used a GNU extension then. Do you think we can use a temporary file switch over to still use a streaming sed to patch the file?

# GNU extension 
foobar="foobar..."
sed -i 's/1/2/' "$foobar"

# POSIX
foobar="foobar..."
temporary="$(mktemp)"
sed 's/1/2/' "$foobar" > "$temporary"
mv "$temporary" "$foobar"