Echidna is a Mac app for generating "shim applications" that allow opening files with terminal programs by double clicking on the files' icons. For example, you could generate a shim app to open double-clicked source files in (n)vim or emacs. Files can also be opened with the selected terminal application by dragging to the shim's icon in the Finder or Dock or selecting the shim app from the Open With menu after right-clicking on the file icon. Echidna's name, like its functionality, is inspired by Platypus (Github), a wonderful Mac app for wrapping scripts in GUIs.

After launching Echidna, first fill out the fields:

• Command: The terminal program to execute. The files, space-delimited, will be appended to this string and passed to the terminal. Only Bash-compatible commands are supported at the moment (due to the quoting required for the command and passed file paths).
• Documents: Document types to support opening. This will control which files your shim app appears in the Open With menu for. Other files will still be openable with Open With -> Other... (perhaps enabling All Applications). NB: UTI is Uniform Type Identifier.
  • Text Files: Support opening text files (UTIs: public.text, public.data)
  • All Documents: Support opening all documents (UTIs: public.content, public.data)
  • Specific UTIs: enter a comma-delimited list of UTIs to support.
  • Specific Extensions: enter a comma-delimited list of extensions to support. Wildcard (*) is no extension.
• Terminal: Select desired terminal application. Currently supported are Terminal.app and iTerm2. To try to use another terminal, select Generic, and enter the terminal's name. An attempt will be make to control the terminal by sending keystrokes (best effort). Permission must first be given for your shim app to control your computer in System Preferences -> Privacy and Security -> Accessbility.
• Open Files: () Together, () Individually: If multiple files are opened simultaneously, should they all be passed to a single instantiation to the command (space-delimited), or should each open in it's own window? Note that this only applies to files opened at one time - files opened thereafter will currently always open in new windows.

A custom icon can also be chosen with "Select Icon...".

Then click Save As…, provide a file name and directory, and click Save. You can then set your shim app as the Open With handler, or launch it to provide a draggable target in the Dock (no windows will appear after being launched, and launching the shim app ahead of time isn't necessary).

• echidna-shim: bin. The binary that runs within the generated shim app, receiving the double-clicked files and launching the terminal session.
• echidna_lib: lib. The library with the core Echidna functionality of generating specialized shim apps.
• echidna-cli: bin. A command line tool to generate shim apps. Essentially a thin wrapper around echidna-lib. By default, echidna-cli looks for an echidna-shim binary in the same directory, but this can be overwritten with a command-line flag. echidna-cli should not be run with cargo run, as Cargo is not aware of the dependency between echidna-cli and echidna-shim, and a stale version of echidna-shim may be used.
• echidna: bin. A GUI tool to generate shim apps. Essentially a (slightly less) thin wrapper around echidna-lib.

TLDR: Run ./build.sh [--debug | --release]

build.sh runs cargo build --all, then scripts/make-app.sh, which builds Echidna.app (in target/{BUILD_MODE}/Echidna.app), a Mac app bundle that includes echidana and echidna-shim.

cargo run should not be used, see echidna-cli above.