.--------.
                                   | I want |
                                   | to ... |
                                   '--------'
                                        |
                                        v
                                  .-----------.
                            yes  / ... search  \  no
                          .-----(  in freeform  )-----------------.
                          |      \    text.    /                  |
                          v       '-----------'                   v
                   ____________                           .---------------.
                   \           \                    yes  /    ... work     \  no
                    ) use grep  )                 .-----(  with structured  )--------.
                   /___________/                  |      \      text.      /         |
                          |                       v       '---------------'          v
                          v                 ___________                       .-------------.
                     .--------.             \          \            replace  /   ... work    \  delete
               yes  /   It's   \  no         ) use awk  )             .-----(  with freeform  )-----.
            .------(  a simple  )-------.   /__________/              |      \     text.     /      |
            |       \ pattern. /        |                             |       '-------------'       |
            v        '--------'         v                             v           extract           v
.-----------------------.  .-------------------------.  .--------------------------. | .-------------------------.
| grep 'simple pattern' |  |  egrep 'regex pattern'  |  | sed 's/search/replace/g' | | | sed '/search pattern/d' |
'-----------------------'  |            or           |  '--------------------------' v '-------------------------'
                           | grep -E 'regex pattern' |           .---------------------------------------.
                           '-------------------------'           | sed 's/^.*\(search pattern\).*$/\1/g' |
                                                                 |                  or                   |
                                                                 |       grep -Po 'search pattern'       |
                                                                 '---------------------------------------'