A simple command shell sorta modeled after gnu bash. For educational purposes. This project will be expanded to include more functionality in the coming weeks.
To install, simply make in the project root directory.
(This project requires boost regex and string libraries to build.)
To run, invoke bin/rshell in bash.
All basic programs in your /bin can be invoked. (This means cd does not work, yet.)
The bash connectors &&, ||, ; are suported and function exactly the same.
Connectors at the beginning of a line are treated as syntax errors.
rshell supports basic piping, as in bash. the format cmd | cmd, cmd < file, cmd > file, and cmd >> file are supported, as well as chaining.
The syntax cmd fd> file is also supported for any (valid) file descriptor.
The syntax cmd <<< "string" causes the string to be read directly into the command's standard input. Note that quotes are currently not parsed. Using these may cause problems and should be avoided.
Both of the above commands can be used in any pipe chain, although input and output are prioritized.
Whitespace is ignored for pipes. They are not affected by connectors. However, note that syntax errors with pipes are only detected at runtime, and will abort execution from that point onward.
Note: cmd < file1 > file2 does not function correctly, and should be avoided.
There is currently only one built-in function: cd.
cd <PATH> takes you to the dir <PATH>, cd - takes you to the previous working directory, and plain cd takes you to the HOME directory.
As in bash, cd will ignore all parameters after the first.
NOTE: Functionality with connectors and piping operators is UNDEFINED, UNTESTED, and should be avoided.
rshell can handle CTRL+C and CTRL+Z signals to terminate and stop foreground processes respectively.
Behavior is UNDEFINED when using with connectors and redirection operators.
The functions fg and bg can be used to manipulate the last spawned process, but there is no stack, so the next process to start will overwrite the last one, with no link back.
When ls is invoked, the flag --color is appended to enable colors.
If you want to modify the source code to better understand the logic, defining the flags RSHELL_DEBUG and RSHELL_PREPEND should help.
This program mostly just invokes stuff in /bin, so it inherits all functionality from them.
Some standard programs partially implemented include mv, cp, rm, and ls.
More advanced bash commands not seen here aren't guaranteed to work at all - in fact, they may crash rshell outright.
Connector syntax and logic was thoroughly tested and all known bugs mended - if you happen to find any wrong behavior, please submit a comment or email me at 'ichor001@ucr.edu'.
Oh and don't ask it to remove itself, strange things will happen.