Civa

A own implementation of a shell

Goals

• Learn UNIX more
• Learn rust more, try not to rely on shell impls in rust, but learn it the hard way
  • Don't use clone (only if reasoned well)
  • Use generics if useful
  • Use lifetimes if useful
• As long as I don't know how dirty code and programs look, I can not build clean code and programs
• Build something I would use, with the approach the build a minimal working program and improve it while reaching its limits

Features

Sequential execution

$ ls || echo "Hello World"
# Same as
$ ls ; echo "Hello World"
# Same as
$ ls && echo "Hello World"

Piping

$ ls | cat

Sudo Substiution

Sudo can be invoked by using ! at the end of a command

$ sudo ls

# equal to

$ ls !

Comes in handy especially when forgetting to use sudo at the beginning of the command

Arithmetic Evaluation

Calculations have to start with a $

$ $ 1 + 1
2

Reserved keyword it for using last result

$ $ 1 + 1
2
$ $ it + 3
5

On the fly arithmetic evaluation which shows the result while typing

Todo

• Make Signal Handling proper (use rustyline or signal_hook?)
• Clip Board
• Improve UI
• Handle command splitting
• Implement PATH search and correct command handling (depending on slash)
• Autocompletion menu and man page/command line autocompletion
• Handle piping
• Make Alias System
• Integration of CMS
  • Git
  • SVN
• Build a config system (python?)
  • Command Bar (UI)
  • Aliases
• Use opiniated builtin alternatives to the GNU/Unix tools
• Tests! (look for good mock library)
• Thinking of ways to improve shell workflows (own opinion)
• Read more
• Setup a more solid test environment, like the exa project with vagrant

Custom Builtins

• ls -> exa
• cat -> bat
• j -> autojump

Sources

• https://pubs.opengroup.org/onlinepubs/9699919799/utilities/contents.html
• https://github.com/tokenrove/build-your-own-shell
• https://indradhanush.github.io/blog/writing-a-unix-shell-part-1/
• https://indradhanush.github.io/blog/writing-a-unix-shell-part-2/
• https://indradhanush.github.io/blog/writing-a-unix-shell-part-3/