jaro is just another resource opener¹. It uses a configuration file to determine which application should be used to open a file. Configuration file is actually a Scheme file which you can use anything that Scheme offers. You don't need to know Scheme to use jaro, configuration is pretty intuitive.

To open some file using jaro, just run:

jaro /path/to/some/file

jaro can also read from stdin.

echo "path/to/file" | jaro

You can disable stdin feature with passing --no-stdin parameter.

Install guile using your package manager. Then just put jaro script somewhere in your path. You can also replace xdg-open script with jaro, if you know what you are doing.

Another option is that you can use this file to redirect xdg-open calls to jaro. Just put it into ~/.config/ directory and put this desktop file into ~/.local/share/applications/.

Only hard dependency is Guile. For enhanced mimetype detection, install mimetype, otherwise jaro will fallback to standard file utility for mimetype detection, which is far more inferior.

jaro looks for the file ~/.config/associations and loads it. This file contains multiple (assoc ...) definitions and arbitrary Scheme code. jaro will try to match the given URI with each association in order. I'll go trough some examples that shows you associating files/uris with programs.

• Here is a pretty basic rule for associating all image types with sxiv:

(assoc
  #:pattern "image/.*"
  #:program "sxiv %f")

• Here is another example that opens all Youtube links with mpv:

(assoc
  #:pattern "^https?://(www.)?youtube.com/watch\\?.*v="
  #:program "mpv %f")

• This association opens given any URL that starts with http or https in qutebrowser if it's already open. If qutebrowser is not open, it'll simply open the URL in Firefox.

(assoc
  #:pattern "^https?://.*"
  #:program "qutebrowser %f"
  #:test "pgrep qutebrowser"
  #:on-fail "firefox %f")

• This example associates all text files with vim. If you call jaro from command-line it'll simply open vim with given file, but if jaro is called from another GUI application it'll open vim in a new terminal. In this example st is the terminal emulator, so that if jaro is called from a GUI application it'll append the #:term parameter before the #:program parameter which will end up like st -e vim %f.

(assoc
  #:pattern "^text/.*"
  #:program "vim %f"
  #:term "st -e")

• This association opens given directory in ranger, like the previous example it runs ranger within a terminal if it's needed. But also if jaro is called within a tmux session, it splits the window and opens ranger in another split.

(assoc
  #:pattern "inode/directory"
  #:program "ranger %f"
  #:term "st -e"
  #:tmux "tmux split-window -h")

An association file may contain all of these associations and jaro will try to match one of them.

A regular expression to match with mimetype or path. This is required. jaro will try to match the pattern with mimetype first, if it fails it'll try to match for the path. This can also be a list of regular expressions, if one of them matches the association will be used. Lists are only for convenience, you can always use grouping with | in a single regular expression.

Examples:

#:pattern "^image/png$"                                     ;; png files
#:pattern "^https?://\\w+\\.com"                            ;; .com websites
#:pattern "\\.mp3"                                          ;; mp3 files
#:pattern '("^application/(x-)?(pdf)$" "^text/postscript$") ;; pdf and postscript files

Patterns may also contain capture groups. You can use these capture groups in #:program and it's derivatives with %1,%2,%3.... For example:

(assoc
    #:pattern "([0-9]+) - (.+)\.mp3"
    #:program "notify-send 'Playing track number %1' 'Track name: %2'; mpv %f")
;; Suppose you called `jaro "02 - From Scythe to Sceptre.mp3"`,
;; It'll send a notification saying "Playing track number 2, Track name: From Scythe to Sceptre" then open it using mpv.

Capture groups do not work when you use list of patterns instead of a single pattern.

The program to open with. This is required. This can either be a string or a list of strings. If it's a string, it will be run in a shell, like /bin/sh. If it's a list of strings, the program will be run directly. Before running, some substitution happens:

• %f is replaced with given relative path, it will be the path that you called jaro with.
• %F is replaced with given path but this will be the absolute path.
• %U is replaced with given path but in URI form. This is useful if the application only accepts URIs (like file:///home/user/file.txt).

Examples:

#:program "vim %f"                               ;; open in vim
#:program "echo %F | xclip -selection clipboard" ;; copy full path to clipboard
#:program '("mpv" "--autofit=1920x1080" "%f")

An arbitrary name to label the association. With given name, you can use the association in other associations. Observe this example:

;; This association opens youtube videos using mpv.
;; If mpv fails to open, it opens the youtube url with
;; association named 'browser.
(assoc
  #:pattern "^https?://(www.)?youtube.com/watch\\?.*v="
  #:program "mpv %f"
  #:on-error (open-with 'browser))

;; The 'browser association
;; This association opens URLs in qutebrowser if it's open;
;; if it's not open, it uses firefox.
;; (The name should start with ')
(assoc
  #:name 'browser
  #:pattern "^https?://.*"
  #:program "qutebrowser %f"
  #:test "pgrep qutebrowser"
  #:on-fail "firefox %f")

You can also use #:continue-on-error #t instead of #:on-error (open-with 'browser) to get the same desired effect in this particular example but labeling associations makes maintaining the associations file easier in the long run.

The program to run #:program with, if jaro is called from outside of a terminal. This command will be prepended in front of #:program before calling. If #:standalone is set to #t, instead of appending before #:program, #:term will be called standalone. Like #:program, this should be either a string or list of strings.

Examples:

;; This will open all text files in vim. When called from outside of terminal,
;; it will open vim in a new terminal.
(assoc
  #:pattern "text/"
  #:program "vim %f"
  #:term "st -e")

;; This will open all text files in vim if it is called in a terminal, but if
;; it is called from outside of a terminal, it will open files in gedit.
;; (Yeah, the name #:term looks confusing here.)
(assoc
  #:pattern "text/"
  #:program "vim %f"
  #:term "gedit %f"
  #:standalone #t)

Command to run if jaro is called inside a tmux session. This command will be prepended in front of #:program before calling. If #:standalone is set to #t, instead of appending before #:program, #:tmux will be called directly. Like #:program, this should be either a string or list of strings.

Examples:

;; Open directories in ranger. If jaro is called inside a tmux session,
;; split window and open ranger in that split.
(assoc
  #:pattern "inode/directory"
  #:program "ranger %f"
  #:tmux "tmux split-window")

;; Open http(s) links in firefox. If jaro is called inside a tmux session,
;; use w3m to open links in a new tmux split.
(assoc
  #:pattern "https?://"
  #:program "firefox %f"
  #:tmux "tmux split-window w3m %f"
  #:standalone #t)

Like #:tmux but for screen.

If this is set to #t; #:term, #:tmux, #:screen will be run standalone, instead of appending before #:program. This is useful for using different programs in different working environments.

A test command. If #:pattern is matched and #:test is present, before calling the #:program, jaro will run #:test. If command exits with 0, #:program will be run. Otherwise jaro will skip this association like it hasn't been matched. Like #:program, this should be either a string or list of strings.

Command to run if the #:test fails. If #:test fails and #:on-fail is present, jaro will execute #:on-fail and stop trying next association.

Example:

;; Test if qutebrowser is running. If it is, then open the url in qutebrowser,
;; if it is not, then open the url in firefox.
(assoc
  #:pattern "^https?://.*"
  #:program "qutebrowser %f"
  #:test "pgrep qutebrowser"
  #:on-fail "firefox %f")

Command to run if #:program (or #:on-fail, #:term, #:tmux, #:screen) exits with something other than 0.

Example:

;; Open images with sxiv. If it fails to open image, opens the image with feh.
(assoc
  #:pattern '"^image/.*$"
  #:program "sxiv %f"
  #:on-error "feh %f")

Command to run if #:program (or #:on-fail, #:term, #:tmux, #:screen) exits with 0.

If this is set to #t; jaro will continent trying to match other patterns when an error happens on the matched association. While you can control what happens when an error happens with #:on-error, you can't control what happens if #:on-error exits with an error. This is useful in situations like that. When you use #:continue-on-error with #:on-error; jaro will call #:on-error first when #:program exits with non-zero value. If #:on-error exits successfully, jaro will stop trying to match. Otherwise it'll continue searching for next match.

Example:

(assoc
  #:pattern '("https?://.+(png|jpg|gif)"
              "^image/")
  #:program "sxiv %f"
  #:on-error "feh %f"
  #:continue-on-error #t)

(assoc
  #:pattern "^https?://.+"
  #:program "firefox %f")

;; Consider this scenario: User opens an URL ending with `png`: "https://example.com/some_pic.png"
;; `sxiv` is unable to open that because it does not support URLs. So `feh` will
;; run. If feh exits successfully, nothing else will happen. But if `feh` also
;; fails to open, jaro will continue matching and it will open the URL with
;; `firefox`.

You can define arbitrary options (like #:edit, #:view etc. Anything but the ones explained above.) and start jaro with a method to use that option. For example:

(assoc
  #:pattern "^text/.*"
  #:program "vim %f"
  #:view "cat %f")

When jaro is started with --method=view, it will open given text file in cat instead of #:program. You can add arbitrary amount of opening modes. These modes, like #:program option, should be either a string or a list of strings (or a scheme procedure).

Another example:

(assoc
  #:pattern "image/.*"
  #:program "sxiv %f"
  #:view "sxiv %f"
  #:edit "gimp %f")

;; As you can see, `#:view` and `#:program` are just the same thing,
;; you can use `#:view #t` to avoid duplication, so this means the
;; same thing with above:

(assoc
  #:pattern "image/.*"
  #:program "sxiv %f"
  #:view #t
  #:edit "gimp %f")

Now you can use jaro --method=view path/to/file or jaro --method=edit path/to/file to open an image. You can define aliases in your shell for these different opening modes, like for bash:

alias edit="jaro --method=edit"
alias view="jaro --method=view"
# ...

#:program or derivatives can also be a procedure. You need to return #t or #f to make things work properly.

Add this association to end of your associations file. If nothing has been matched, this association will run and present you a dialog to select which application to use. It will display programs that supports opening mimetype of given file and all the binaries in your system.

;; If jaro is called inside a terminal, it will use fzf for selecting the
;; alternative, otherwise it will use dmenu. `select-alternative-with` function
;; simply pipes alternatives to given program, so you can use any other
;; dmenu-like program.
(assoc
  #:pattern ".*"
  #:program (select-alternative-with "fzf")
  #:term (select-alternative-with "dmenu")
  #:standalone #t)

;; This one uses dmenu all the time
(assoc
  #:pattern ".*"
  #:program (select-alternative-with "dmenu")
  #:standalone #t)

1: I'm bad at naming stuff ↩