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diff --git a/_tils/2020-08-28-grep-online-repositories.md b/_tils/2020-08-28-grep-online-repositories.md new file mode 100644 index 0000000..a9e0166 --- /dev/null +++ b/_tils/2020-08-28-grep-online-repositories.md @@ -0,0 +1,126 @@ +--- +title: Grep online repositories +date: 2020-08-28 +layout: til +lang: en +ref: grep-online-repositories +--- + +I often find interesting source code repositories online that I want to grep for +some pattern but I can't, because either: + +- the repository is on [cgit][cgit] or a similar code repository that doesn't + allow search in files, or; +- the search function is really bad, and doesn't allow me to use regular expressions for searching patterns in the code. + +[cgit]: https://git.zx2c4.com/cgit/ + +Here's a simple script that allows you to overcome that problem easily: + +```shell +#!/usr/bin/env bash +set -eu + +end="\033[0m" +red="\033[0;31m" +red() { echo -e "${red}${1}${end}"; } + +usage() { + red "Missing argument $1.\n" + cat <<EOF +Usage: + $0 <REGEX_PATTERN> <REPOSITORY_URL> + + Arguments: + REGEX_PATTERN Regular expression that "git grep" can search + REPOSITORY_URL URL address that "git clone" can download the repository from + +Examples: + Searching "make get-git" in cgit repository: + git search 'make get-git' https://git.zx2c4.com/cgit/ + git search 'make get-git' https://git.zx2c4.com/cgit/ -- $(git rev-list --all) +EOF + exit 2 +} + + +REGEX_PATTERN="${1:-}" +REPOSITORY_URL="${2:-}" +[[ -z "${REGEX_PATTERN}" ]] && usage 'REGEX_PATTERN' +[[ -z "${REPOSITORY_URL}" ]] && usage 'REPOSITORY_URL' + +mkdir -p /tmp/git-search +DIRNAME="$(echo "${REPOSITORY_URL%/}" | rev | cut -d/ -f1 | rev)" +if [[ ! -d "/tmp/git-search/${DIRNAME}" ]]; then + git clone "${REPOSITORY_URL}" "/tmp/git-search/${DIRNAME}" +fi +pushd "/tmp/git-search/${DIRNAME}" + +shift 3 || shift 2 # when "--" is missing +git grep "${REGEX_PATTERN}" "${@}" +``` + +It is a wrapper around `git grep` that downloads the repository when missing. +Save in a file calle `git-search`, make the file executable and add it to your +path. + +Overview: + +- *lines 1~2*: + + Bash shebang and the `set -eu` options to exit on error or undefined + variables. + +- *lines 4~30*: + + Usage text to be printed when providing less arguments than expected. + +- *line 33*: + + Extract the repository name from the URL, removing trailing slashes. + +- *lines 34~37*: + + Download the repository when missing and go to the folder. + +- *line 39*: + + Make the variable `$@` contain the rest of the unused arguments. + +- *line 40*: + + Perform `git grep`, forwarding the remaining arguments from `$@`. + +Example output: +```shell +$ git search 'make get-git' https://git.zx2c4.com/cgit/ +Clonage dans '/tmp/git-search/cgit'... +remote: Enumerating objects: 542, done. +remote: Counting objects: 100% (542/542), done. +remote: Compressing objects: 100% (101/101), done. +warning: object 51dd1eff1edc663674df9ab85d2786a40f7ae3a5: gitmodulesParse: could not parse gitmodules blob +remote: Total 7063 (delta 496), reused 446 (delta 441), pack-reused 6521 +Réception d'objets: 100% (7063/7063), 8.69 Mio | 5.39 Mio/s, fait. +Résolution des deltas: 100% (5047/5047), fait. +/tmp/git-search/cgit ~/dev/libre/songbooks/docs +README: $ make get-git +$ git search 'make get-git' https://git.zx2c4.com/cgit/ +/tmp/git-search/cgit ~/dev/libre/songbooks/docs +README: $ make get-git +$ git search +Missing argument REGEX_PATTERN. + +Usage: + /home/andreh/dev/libre/dotfiles/scripts/ad-hoc/git-search <REGEX_PATTERN> <REPOSITORY_URL> + + Arguments: + REGEX_PATTERN Regular expression that "git grep" can search + REPOSITORY_URL URL address that "git clone" can download the repository from + +Examples: + Searching "make get-git" in cgit repository: + git search 'make get-git' https://git.zx2c4.com/cgit/ + git search 'make get-git' https://git.zx2c4.com/cgit/ -- $(git rev-list --all) +``` + +Subsequent greps on the same repository are faster because no download is needed. |