Use grep command for searching a string in a file
https://pupli.net/2022/02/use-grep-command-for-searching-a-string-in-a-file/
grep match lines that do not contain pattern
https://pupli.net/2019/07/29/grep-match-lines-that-do-not-contain-pattern/
grep match lines starts with pattern
https://pupli.net/2019/07/grep-match-lines-starts-with-pattern/