Extract numbers from string using shell

Question

Using shell script, how do I extract two sets of numbers from a string like "R14C11"? I'd like to get the result as an AppleScript list.

R14C11 -> {14, 11}
R5C9   -> {5, 9}

"R" and "C" will be constants but the number of digits in each set of numbers can vary.

Answer 1

There are a lot of ways to do this, one is to use sed

echo R5C9 | sed -E 's|R(.*)C(.*)|{\1, \2}|'

Or, if you want to ensure that only input with the correct format will be matched

echo R5C9 | sed -E 's|R([[:digit:]]+)C([[:digit:]]+)|{\1, \2}|'

Some explanations:

• -E enables extended regular expressions, which among other things makes the matching of the pattern easier
• s|SOURCE|TARGET| is the substitution command to transform SOURCE into TARGET
• R([[:digit:]]+)C([[:digit:]]+) is the source pattern we are looking for: An R followed by at least one digit [[:digit:]]+ followed by C followed again by at least one digit
• The target replaces the matched source, with \1 standing for the text matched within the first () in the source, \2 for the second

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You can also just use bash itself

[[ "R5C9" =~ R([0-9]+)C([0-9]+) ]] && echo "{${BASH_REMATCH[1]}, ${BASH_REMATCH[2]}}"

• [[ "R5C9" =~ R([0-9]+)C([0-9]+) ]] matches the text, with R([0-9]+)C([0-9]+) being basically the same as the source pattern above
• Matching parts within () get assigned to the shell array BASH_REMATCH
• The echo is only executed if the match ([[ ... ]]) was successfull, and then prints the reformatted expression (which is a bit confusing to read because the various {} mean different things...)