hallerpatrick / civa

Own shell implementation in Rust

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/

civa's Issues

Bug Piping not working

cat test.txt | less

Civa should crash on wrong input

Example:

´´´bash
...
´´´

Error:
thread 'main' panicked at 'called Result::unwrap() on an Err value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/env/environment.rs:141:9
stack backtrace:
0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
1: core::fmt::write
2: std::io::Write::write_fmt
3: std::panicking::default_hook::{{closure}}
4: std::panicking::default_hook
5: std::panicking::rust_panic_with_hook
6: rust_begin_unwind
7: core::panicking::panic_fmt
8: core::option::expect_none_failed
9: civa::env::environment::EnvManager::canonicalize_path
10: civa::command::handler::handle_commands
11: civa::main
12: std::rt::lang_start::{{closure}}
13: std::panicking::try::do_call
14: __rust_maybe_catch_panic
15: std::rt::lang_start_internal
16: main
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.

Trailing component for command bar

{COMMAND_BAR}{PROMPT}........{TRAILING_BAR}

Listen to terminal size...

allow for arithmetic expressions

Maybe go for on the fly calculation for direct display

Correct command parsing

command with quotes are not working yet

E.g.:

git commit -m "Hello world"

Output:
[git, commit, -m, "Hello", "world"]

Fold command line bar and text by rezising