--- title: "@protesilaos: 이맥스 정규식 기본" url: "https://notes.junghanacs.com/notes/20250422T174538" author: "Junghan Kim" date: "2025-04-22T17:45:00+09:00" lastmod: "2025-04-22T17:45:00+09:00" tags: ["guide","bib","emacs"] description: "Protesilaos의 Emacs 정규식 입문 자료를 참고하려고 남긴 노트이다." --- > [!abstract] 이 노트에 대하여 > > Prot의 정규식 기초 자료를 바탕으로 Emacs 안에서 isearch와 query-replace, keep-lines, flush-lines를 어떻게 쓸지 정리한다. 정규표현식 실전 입문 노트다. ## 히스토리 - [2026-09-01 Tue 22:55] 이것도 정리 해야겠다. - [2025-04-22 Tue 17:45] 2020년도 자료인데 옮긴다. ## BIBLIOGRAPHY - Stavrou, Protesilaos. 2020. “Primer on Regular Expressions inside of Emacs.” January 23, 2020. . ## Primer on regular expressions inside of Emacs [#정규표현식](https://notes.junghanacs.com/meta/20230727T091700) 를 본다면 ([Stavrou 2020](https://notes.junghanacs.com/notes/20250422T174538#citeproc_bib_item_1)) - Stavrou, Protesilaos - In this video tutorial I show how to use regexp notation to solve practical problems in Emacs. Protesilaos Emacs has a few ways to operate on regexp matches, such as: - `isearch` - `query-replace` - `keep-lines` - `flush-lines` To make our life easier, we can practice with the built-in `regexp-builder` or the third-party package `visual-regexp`. This demo will rely on the latter. If you have the manual you can run `C-h r i regexp` to get to the relevant chapter. **Do it!** ### Line boundaries The caret `^` denotes the beginning of the line. The dollar sign `$` marks the end. Match all lines that start with a space: Emacs Emacs Emacs Emacs Emacs And all that end with a capital `S`: emacs emacS emacS emacs emacs emacs emacS emacS 헤드라인을 네로우 하면 여기에 집중할 수 있다. 여기서 말하는 것은 isearch-regex 를 이용해서 라인 바운더리를 오가는 것이다. 만약 맨 뒤에 S 만 있는 라인을 가려면 `isearch-toggle-regexp` 에서 S$ 을 입력하면 된다. evil 에도 뭔가 있을 텐데 프롯은 정통파라 ### Remove or keep lines Remove the empty lines. Then keep the ones that contain "username". <username><\![CDATA[name]]></username> emacs emacS emacS emacs emacs emacs emacS emacS <userName><\![CDATA[nom]]></userName> emacs emacS emacS emacs emacs emacs emacS emacS <username><\![CDATA[name]]></username> emacs emacS emacS emacs emacs emacs emacS emacS `whitespace-mode` 를 켜니까 공백이 다 보인다. 와. 몰랐다. `SPC t w` 에 바인딩 되어 있네. 마우스로 영역 잡고 `flush-lines` ^$ 하니까 빈 라인이 다 사라졌다. 와우! 그 다음에 `keep-lines` username 을 적으면 username 이 없는 라인은 다 사라진다. ### The dot character The dot or full stop `.` means matches every character except the newline. Match these words using their common part `ired` as a string. dired fired mired tired wired > Mark saved where search started [2 times] 이게 뭔가? set-mark 를 어떻게 꺼내 쓰는가? ### Character sets and ranges A set of individual characters is marked between brackets `[]`. Sets can be written as ranges: | Range | Scope | |------------|--------------------------------------------| | [a-z] | all lower cases alphabetic characters | | [A-Za-z] | all upper or lower case letters | | [a-z0-9] | lower case alphabet or numbers 0 through 9 | | [abcd1234] | letters a,b,c,d and numbers 1,2,3,4 | Match both of those using a character set for the first letter: emacs Emacs Match those that end with a number: Emacs emacs-27 emacs-26 GNU emacs 해보자! 어떻게 하나면! 잘 된다. ### Difference between postfix operators ?, +, \* "Postfix" means that it comes after a given set and alters its scope. "포스트픽스"는 주어진 집합 뒤에 와서 그 범위를 변경하는 것을 의미합니다. `?` match the previous term zero or one time. `+` match the previous term one or more times. `*` match the previous term zero or as many times as possible. Match the `s` optionally: day days Use `prote` followed by a postfix: prot prote proteeee 어떻게 하는가요? 프롯은 isearch 를 사용한다. 뭐든 좋다. 기본은 기본대로 해야 된다. 잠시만. ### Grouped matches A group is enclosed inside escaped parentheses `\(GROUP\)`. Match both of these, including the optional suffix `ig`: conf config > 보자 보자! `conf\(ig\)?` 를 이용해서 해보자. 즉 그룹을 만들어서 해당 영역을 묶는 것이다. 유용하다. ### Greedy versus non-greedy Postfix charaacter are greedy by default. "Greedy" matches the longest possible part. Whereas "non-greedy" corresponds to the shortest. A non-greedy variant is used when the postfix is followed by `?`. Using the `.*` construct, match items both greedily and not: Hello world Hello world world world world > \*\* Multiple groups Match the alphabetic and numeric parts in two separate groups. emacs27 emacs26 emacs25 emacs24 ### Literal hyphen and dot Match the hyphen as part of the alphabetic group and the dot as part of the numeric one. emacs-27.1 emacs-26.3 emacs-25.2 ### Exclude sets To exclude a set you prepend a caret sign: `[^SET]` Match every line except those that start with a capital letter. GNU Emacs org-mode regexp emacs_lisp Linux guix ### Alternative groups with literal brackets Use a character sets that matches `name` and `nom`. name nom Then: 1. Match the `username` variants' `[name]` or `[nom]`. 2. Replace the match with `[PROT]`. <username><\![CDATA[name]]></username> <nameuser><\![CDATA[nam]]></nameuser> <userName><\![CDATA[nom]]></userName> <nameuser><\![CDATA[nome]]></nameuser> ### Either match To target either set, use `\|`. Prepend `vr/` to the first `group` and `match` on each line. \`(group-0 ((group (:inherit modus-theme-intense-blue)))) \`(group-1 ((group (:inherit modus-theme-intense-magenta)))) \`(group-2 ((group (:inherit modus-theme-intense-green)))) \`(match-0 ((match (:inherit modus-theme-refine-yellow)))) \`(match-1 ((match (:inherit modus-theme-refine-yellow)))) ### Running elisp functions on groups Run elisp by escaping the comma `\,` and then following it with a symbol inside parentheses: `\,(FUNCTION)`. Using the `.ired` pattern from earlier, run a replace command where you must execute the `upcase` function on the second/middle match. Keep the rest in tact. direddireddired firedfiredfired miredmiredmired tiredtiredtired wiredwiredwired