macOS bash script regular expression not working as expected

Question

I've been out of programming for more than 10 years. I have a text file that I'm trying to read the Mpbs value for the upload and download speed.

 Server: Iomart - Maidenhead (id = 3839) ISP: Plusnet Latency: 8.59 ms (0.10 ms jitter) Download: 71.43 Mbps (data used: 52.8 MB) Upload: 18.39 Mbps (data used: 16.9 MB) Packet Loss: 0.0% 

I've been using a regex tool to test and build my regex, which delivers the result I want.

regex2="Upload:\W+([0-9]+\.[0-9]+)" regex3="Download:\W+([0-9]+\.[0-9]+)" while read line; do if [[ $line =~ regex2 ]] then echo "match ${BASH_REMATCH[1]}" UPS=${BASH_REMATCH[1]} fi if [[ $line =~ regex3 ]] then echo "match ${BASH_REMATCH[1]}" DNS=${BASH_REMATCH[1]} fi done < Result.txt 

I'm sure there must be a better way to achieve what I want, but the main problem I'm having is the regex not working.

Answer 1

You have three issues in your code.

1. You're not using the regular expressions you think you are (missing $ on regex2 and regex3).
2. bash does not understand the Perl-like regular expression \W as "not a word character".
3. You are not reading lines (even though your variable is called line).

To solve this:

1. Use $ on to get the values of regex2 and regex3 in the tests:

   if [[ $line =~ $regex2 ]]; then ...; fi 

2. Use the POSIX regular expression [^[:alnum:]_] in place of \W in the expressions, or [[:blank:]] which matches a tab or space.

3. Use while IFS= read -r line; do ...; done (see "Understanding "IFS= read -r line"").