My current code:
while read -r rbv_line || [[ -n "$rbv_line" ]]; do
if [[ "${rbv_line}" =~ ${rbv_reg} ]]; then
rbv_downcase="${BASH_REMATCH[0],,}" &&
ruby_version="${rbv_downcase//[^0-9a-z\.\-]/}" &&
((reg_matches="${reg_matches}"+1))
printf "\n"
printf "Setting Ruby version: %s\n" "${ruby_version}"
break
fi
done < "${1}"
It does what I want. But I would love to know if I can simplify this code even more, hoping someone can help me understand the syntax.
If you see these two lines:
rbv_downcase="${BASH_REMATCH[0],,}" &&
ruby_version="${rbv_downcase//[^0-9a-z\.\-]/}" &&
Initially I tried to combine those into one using something like this:
ruby_version="${BASH_REMATCH[0],,//[^0-9a-z\.\-]/}"
That does not work.
Is there a way to combine those two parameter expansions (,,
and the //[^0-9a-z\.\-]/
) or is passing it through an intermediary variable the right approach?
You can view the latest version of the code here: https://github.com/octopusnz/scripts
You cannot combine multiple parameter expansions, but...
... you can simplify this code!
The biggest gain is by using already available tools.
grep
. It's supposed to do something when RegEx pattern is occurred, so:grep -E "$rbv_reg" "$1" # -E is for extended RegEx
-i
flag.-m 1
to stop processing file after first match.tr
:grep -m 1 -E -i "$rbv_reg" "$1" | tr '[:upper:]' '[:lower:]'
//[^0-9a-z\.\-]/
, piping it to sed
will do the trick:grep -m 1 -E -i "$rbv_reg" "$1" | tr '[:upper:]' '[:lower:]' | sed 's/[^0-9a-z\.\-]//g'
ruby_version="$( grep -m 1 -E -i '$rbv_reg' '$1' | tr '[:upper:]' '[:lower:]' | sed 's/[^0-9a-z\.\-]//g' )"
echo
instead of printf
if [ -n "$ruby_version" ]
to increment reg_matches
At the end, we got:
ruby_version="$(
grep -m 1 -E -i '$rbv_reg' '$1' |
tr '[:upper:]' '[:lower:]' |
sed 's/[^0-9a-z\.\-]//g'
)"
if [ -n "$ruby_version" ]; then
reg_matches="$((reg_matches+1))"
echo
echo "Setting Ruby version: $ruby_version"
fi
The advantage of above code is the fact it isn't really Bash dependent and should work in any POSIX Bourne compatible shell.