3 ms·

I wish grep had capture groups so I could do things like grep "\((\d+)\)" -print "$1" file.txt

• defrost 4y ago
  ripgrep is a modern faster grep in Rust, some cons, many pros. It'll do capture groups with search | replace # remove square brackets that surround digit characters $ echo '[52] apples [and] [31] mangoes' | rg '\[(\d+)]' -r '$1' 52 apples [and] 31 mangoes
  • asicsp 4y ago
    Pleasantly surprised to see an example from my ebook :) Add `-o` option to get only the digits: $ echo '[52] apples [and] [31] mangoes' | rg -o '\[(\d+)]' -r '$1' 52 31
    • defrost 4y ago
      Congratulations (?) for making the top five google results for "ripgrep capture groups" [1]. I cite sources way more often than not, this time I got lazy after dithering over whether to go with the definitive ripgrep source page [2] or a decent looking third party(?) tutorial .. pressed for time I did neither. [1] https://learnbyexample.github.io/learn_gnugrep_ripgrep/ripgrep.html https://learnbyexample.github.io/learn_gnugrep_ripgrep/ripgr... [2] https://github.com/BurntSushi/ripgrep https://github.com/BurntSushi/ripgrep
• asicsp 4y ago
  If PCRE is supported: grep -oP '\(\K\d+(?=\))' The above will give all matches in a line though. You can remove `(?=\))` part if numbers are always enclosed in `()` or if you don't care about the `)`
  • forinti 4y ago
    Lookarounds are a bit messy. It's easier to just pipe into a second grep.
    • sargstuff 4y ago
      certainly gets rid of one type of edge case.
• sargstuff 4y ago
  [1] gives some background about the issue and possible solution(s). [1] : https://unix.stackexchange.com/questions/536657/how-to-refer-to-a-regex-group-in-awk-regex https://unix.stackexchange.com/questions/536657/how-to-refer...