tosh / (tɒʃ) / noun. slang, mainly British nonsense; rubbish.
A very simple shell written for fun (and learning) in C, initially heavily following Stephen Brennan's nice blog post.
Compile for your chosen architecture, and invoke however you like: from your preferred shell as ./tosh, or run it on its own (like a proper shell!) with exec ./tosh (which is a builtin wrapper for the exec() system call that most shells seem to have). Put it in ~/bin or somewhere, if you like (and add this to your PATH).
Pass data in via standard input like ./tosh < file or pass a file (several lines of commmands for tosh) as an argument like ./tosh file.
-v(start in verbose mode)-d(start in debug mode)-i(force it to behave as if it were interactive)
Can be combined: -dv, for example. These options are also adjustable via environment variables; run env from within tosh to have a look.
Type help to see some more info.
- traverse the filesystem with
cd - run commands and pass them arguments with the usual syntax (including quotes)
- custom prompt string (with formatting, and optional rainbow colours!)
- filename globbing (
*and?metacharacters) - inline recursive command substitution (execution in a subshell)
- control behaviour with tosh-specific environment variables
- history file in a chosen location
- read commands from a file (i.e. execute shell scripts)
- pipes
- I/O redirection (to and from files)
- config files
- environment variable substitution and editing
I wanted to include other nice features like tab completion, up arrow to browse history, live completion suggestion of paths/filenames, etc., but since this requires unbuffered access to the input stream it turns out not only to be highly platform-dependent but also particularly difficult on macOS. ...but it must be possible with some more effort.