
## Firefox

- To set Firefox Developer Edition as `sensible-browser` on Linux:

  First, add Firefox Developer Edition to `update-alternatives`:

  ```shell
  sudo update-alternatives --install /usr/bin/x-www-browser x-www-browser /opt/firefox_dev/firefox/firefox 200
  ```

  (Assuming the executable path `/opt/firefox_dev/firefox/firefox`)

  Then, set it as `sensible-browser`:

  ```shell
  sudo update-alternatives --config x-www-browser
  ```

### `about:config` settings

| Option                                  | Change        | Notes                   |
|-----------------------------------------|---------------|-------------------------|
| `geo.enabled`                           | true -> false |                         |
| `extensions.pocket.enabled`             | true -> false |                         |
| `browser.bookmarks.openInTabClosesMenu` | true -> false |                         |
| `browser.bookmarks.showMobileBookmarks` | true -> false |                         |
| `browser.bookmarks.autoExportHTML`      | false -> true |                         |
| `browser.tabs.loadBookmarksInTabs`      | false -> true |                         |
| `browser.tabs.tabMinWidth`              | 76 -> 100     |                         |
| `browser.tabs.closeTabByDblclick`       | false -> true |                         |
| `browser.tabs.closeWindowWithLastTab`   | true -> false |                         |
| `browser.privatebrowsing.autostart`     | false -> true |                         |
| `browser.urlbar.openintab`              |               |                         |
| `pdfjs.ignoreDestinationZoom`           | false -> true |                         |
| `pdfjs.spreadModeOnLoad`                | -1 -> 2       | Even spreads by default |

### Useful shortcuts

[Firefox keyboard shortcuts](https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly)

| Shortcut                   | Action                                          |
| -------------------------- | ----------------------------------------------- |
| `Home`                     | Move to the top of the page. (See also: Vimium) |
| `Ctrl-l`                   | Highlight the url bar.                          |
| `Ctrl-Shift-o`             | Open bookmark manager.                          |
| `Ctrl-Shift-b`             | Toggle bookmarks toolbar.                       |
| `Ctrl-b`                   | Toggle bookmarks sidebar.                       |
| `Ctrl-Shift-d`             | Bookmark all open tabs in a folder.             |
| `Ctrl-Shift-a`             | Open addons manager.                            |
| `Ctrl-Shift-Del`           | Clear recent history.                           |
| `Ctrl-Shift-r` / `Ctrl-F5` | Reload the tab and clear the cache.             |
| `Ctrl-Shift-t`             | Undo close tab.                                 |


Browsers

[Top]

Firefox

`about:config` settings

Useful shortcuts


## VSCode

[Keyboard shortcuts for Linux](https://code.visualstudio.com/shortcuts/keyboard-shortcuts-linux.pdf)

| Shortcut            | Action                          |
| ------------------- | ------------------------------- |
| `Ctrl-Shift-p`      | Open Command Palette.           |
| `Ctrl-,`            | Open user settings.             |
| `Ctrl-b`            | Toggle Explorer.                |
| `Ctrl-Shift-d`      | Open Run and debug.             |
| `Ctrl-j`            | Toggle built-in terminal.       |
| `Ctrl-p`            | Open a file.                    |
| `Ctrl-Tab`          | Tab through open files.         |
| `Ctrl-\`            | Move file to split windows.     |
| `Ctrl-f`            | Search/Replace in file.         |
| `Ctrl-Shift-f`      | Open Global Search.             |
| `Ctrl-/`            | Toggle comment.                 |
| `Shift-Alt-Up/Down` | Duplicate line.                 |
| `Ctrl-Click`        | Multiple cursors.               |
| `Ctrl-d`            | Select word under the cursor.   |
| `Ctrl-Shift-l`      | Select all instances of a word. |
| `Ctrl-Click`        | Jump to function definition.    |
| `Ctrl-k z`          | Zen Mode.                       |

## Sublime Text

To enable Vim mode, go to user settings (**Settings** > **Preferences**) and remove `Vintage` from `ignored_packages` array.

## gedit

- `Ctrl-;`: Open emoji window.
- `F9`: Toggle side panel.
- Install [Dracula theme](https://draculatheme.com/gedit)
  ```shell
  wget https://raw.githubusercontent.com/dracula/gedit/master/dracula.xml
  mv dracula.xml $HOME/.local/share/gedit/styles/
  # Activate in gedit's preferences dialog.
  ```


Text editors and IDEs


- [Regex cheatsheet - MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Cheatsheet)
- [Regex cheatsheet - docs.linuxfoundation.org](https://docs.linuxfoundation.org/v2/security-service/manage-false-positives/regular-expressions-cheat-sheet)

## Character classes

| Character | Meaning                      |
| --------- | ---------------------------- |
| `.`       | Any character except newline |
| `\d`      | One digit                    |
| `\D`      | One non-digit                |
| `\s`      | One whitespace               |
| `\S`      | One non-whitespace           |
| `\w`      | One word character           |
| `\W`      | One non-word character       |
| `\t`      | Horizontal tab               |
| `\v`      | Vertical tab                 |
| `\r`      | Carriage return              |
| `\n`      | Newline/Linefeed             |
| `\f`      | Form-feed                    |
| `[\b]`    | Backspace character          |
| `\0`      | NUL character                |
| `\`       | Escape a special character   |

## Assertions

| Character | Meaning                                                              |
| --------- | -------------------------------------------------------------------- |
| `^`       | Start of string                                                      |
| `$`       | End of string                                                        |
| `\b`      | Word boundary                                                        |
| `\B`      | Non-word boundary                                                    |
| `x(?=y)`  | Positive lookahead (Matches "x" only if "x" is followed by "y")      |
| `x(?!y)`  | Negative lookahead (Matches "x" only if "x" is not followed by "y")  |
| `(?<=y)x` | Positive lookbehind (Matches "x" only if "x" is preceded by "y")     |
| `(?<!y)x` | Negative lookbehind (Matches "x" only if "x" is not preceded by "y") |

## Groups and ranges

| Character             | Meaning                                                                                     |
| --------------------- | ------------------------------------------------------------------------------------------- |
| <code>x&#124;y</code> | Either "x" or "y"                                                                           |
| `[xyz]` `[a-c]`       | Any one of the enclosed characters                                                          |
| `[^xyz]` `[^a-c]`     | Anything that is not enclosed in the brackets                                               |
| `(x)`                 | Capturing group (matches "x" and remembers the match)                                       |
| `(?<Name>x)`          | Named capturing group (matches "x" and stores it as "Name")                                 |
| `(?:x)`               | Non-capturing group (matches "x" but does not remember the match)                           |
| `\N`                  | Match the Nth captured group                                                                |
| `\k<Name>`            | Back reference to the last substring matching the named capturing group specified by "Name" |

## Quantifiers

| Character | Meaning                                                           |
| --------- | ----------------------------------------------------------------- |
| `*`       | 0 or more                                                         |
| `+`       | 1 or more                                                         |
| `?`       | 0 or 1                                                            |
| `x{n}`    | Exactly n occurences of x                                         |
| `x{n, m}` | Between n and m occurences of x                                   |
| `x{n,}`   | n or more occurences of x                                         |
| `?`       | Make the quantifier non-greedy (stop as soon as it finds a match) |

## POSIX classes

| Character    | Meaning                          |
| ------------ | -------------------------------- |
| `[:alnum:]`  | Letters and digits               |
| `[:alpha:]`  | Letters                          |
| `[:ascii:]`  | Ascii codes 0 - 127              |
| `[:blank:]`  | Space or tab only                |
| `[:cntrl:]`  | Control characters               |
| `[:digit:]`  | Decimal digits                   |
| `[:graph:]`  | Visible characters, except space |
| `[:upper:]`  | Uppercase letters                |
| `[:lower:]`  | Lowercase letters                |
| `[:word:]`   | Word characters                  |
| `[:print:]`  | Visible characters               |
| `[:punct:]`  | Visible punctuation characters   |
| `[:space:]`  | Whitespace                       |
| `[:xdigit:]` | Hexadecimal digits               |


Option	Change	Notes
`geo.enabled`	true -> false
`extensions.pocket.enabled`	true -> false
`browser.bookmarks.openInTabClosesMenu`	true -> false
`browser.bookmarks.showMobileBookmarks`	true -> false
`browser.bookmarks.autoExportHTML`	false -> true
`browser.tabs.loadBookmarksInTabs`	false -> true
`browser.tabs.tabMinWidth`	76 -> 100
`browser.tabs.closeTabByDblclick`	false -> true
`browser.tabs.closeWindowWithLastTab`	true -> false
`browser.privatebrowsing.autostart`	false -> true
`browser.urlbar.openintab`
`pdfjs.ignoreDestinationZoom`	false -> true
`pdfjs.spreadModeOnLoad`	-1 -> 2	Even spreads by default

Shortcut	Action
`Home`	Move to the top of the page. (See also: Vimium)
`Ctrl-l`	Highlight the url bar.
`Ctrl-Shift-o`	Open bookmark manager.
`Ctrl-Shift-b`	Toggle bookmarks toolbar.
`Ctrl-b`	Toggle bookmarks sidebar.
`Ctrl-Shift-d`	Bookmark all open tabs in a folder.
`Ctrl-Shift-a`	Open addons manager.
`Ctrl-Shift-Del`	Clear recent history.
`Ctrl-Shift-r` / `Ctrl-F5`	Reload the tab and clear the cache.
`Ctrl-Shift-t`	Undo close tab.

Browsers

Firefox

about:config settings

Useful shortcuts

`about:config` settings