#Rshell Note: There are bugs and messy/undocumented code but since I am finished with the CS100 course, I will no longer update this project. This project is a shell that interprets and executes lines of command, including the commands, their arguments, and connectors. It simulates the functionality of the bash shell. This project is made for an assignment for the CS100 course, a course on open source software construction, at University of California, Riverside.

##Features Bash commands and signals:

• ls (-l, -a, -R flags)
• cp
• mv
• rm (-r flag)
• cd, cd <PATH>, and cd -
• ^C Input and Output Redirection
• < and <<<
• >, >>, 2>, and 2>>, where 2 may be any number
• |

##Dependencies rshell requires the Boost Libraries for C++ to be installed.

The UCR lab machines, with cs100 settings, already have the Boost Libraries installed.

To install the libraries on Linux Mint, run sudo apt-get install libboost-all-dev

Otherwise, download Boost from www.boost.org/users/download/ ##Install/Run To install, type the following into the terminal:

$ git clone https://github.com/pockymons/rshell.git
$ cd rshell
$ git checkout hw0
$ make

To run, type the following into the terminal, while you are in the rshell directory:

$ bin/rshell

##Edge Cases ###rshell

• I chose to make comments only work if there is a space before the # symbol, just like bash does it.

• Connectors are ordered from left to right. The command before a connector is checked for each connector. There is no order of precedence.

• Whitespace followed by a connector will have the same effect as a ; connector. For example, the following code will have the same result as the ls command.

       && ls
  

• Having an exit command in piping will exit the rshell. This is unlike bash. A bash shell will not do anything (at all) if there is an exit command in a pipe.

• Having multiple io redirections will act just as bash does, meaning that the rightmost output redirection and input redirection will be used. This also means that all output redirections with just 1 angle bracket (> file1, >file2, etc) will result in truncating the file. Only the rightmost will be overwritten.

• Errors in the pipe will cause the entire command to end, even if there is a connector. For example the following command would end after the nonexistent qwer command:

   ls | qwer | cat     || ls
  

• To perform output redirection on whatever file descriptor you want, you must have a space before the file descriptor number and the file descriptor number must be immediately before the output redirection symbol. Rshell can technically take any number as a file descriptor number, but Linux systems only have descriptor numbers 0-9. Also, taking a number from 3-9 is impractical, as they are usually not open.

##Limitations/Bugs

rshell

• Prompt only works for up to 64 characters.

• If there is whitespace only after a connector, it will just act as if it is then end, instead of outputting an error message.

• Pressing the up arrow key does not go to the previous command

• Press tab does not auto-complete a command/directory

• The || and && connectors only work in even groupings. Otherwise, they are interpreted as commands or part of a command.

• Comments only work if there is a command preceding them. If a line has nothing but a comment, there will be an error.

• "Built-in" bash commands are not executed (such as cd).

• If a connector is the first text in a line, there will be unintended or unexpected behavior. For the && and ; connectors, the following command will be run twice. However, the || connector will behave as expected and just run the command once. However, if there is some whitespace then the connector will behave as it described in the Edge Cases section. This means that the following line will behave as though there is no whitespace and no ; connector in the beginning and just run the ls command.

      ; ls
  

• You cannot pipe too many times, just like in bash. If you pipe too many times you will get an error, something like Fork: Resource temporarily unavailable. You can pipe approximately 15 times.

• You can only change directories if the full path of the directory is 4096 characters or less.

• In the testing file, signals.script, the shell is exited a few times (my mistake). After exiting, I immediately enter again. Also, in that testing file, there are a few tests that should not be there. The "tests" are only there because I forgot about some of the functionality of my shell. One of the tests that should not be there is the ^C test with the bash script. I forgot that I can't do bash scripts in the shell.

• >>> does not work for multiple words

ls

• The GNU ls program will output the year in the -l flag, if the last modified date is older than 6 months. My program does not.
• My ls does not list the symbolic links.
• The -R flag has spacing inconsistencies, including an extra space at the end of the output as well as if a directory has no files.
• There are no colors distinguishing each file type.