#Rshell ##Introduction This program is a command shell called rshell. Rshell uses syscalls fork(), waitpid() and execvp() to execute commands from user input. It can perform the following steps:

1. Print a command prompt [rshell]username@hostname $

2. Read in a command on one line. Commands will have the form:

   cmd         = executable [ argumentList ] [ connector cmd ];
   connector   = || or && or ;
   

where executable is an executable program in the PATH and argumentList is a list of zero or more arguments separated by spaces. The connector is an optional way you can run multiple commands at once. If a command is followed by ;, then the next command is always executed; if a command is followed by &&, then the next command is executed only if the first one succeeds; if a command is followed by ||, then the next command is executed only if the first one fails.

Anything between two connectors(including the beginning and the end of an input line) would be considered as an executable command and be passed into execvp(). For example, ;;would be considered as three empty commands. And &&&would be considered as an empty command and &, which is a wrong command, connected by &&. Notice this is different from original bash.

Anything that appears after a # character will be considered as comment.

Prerequisites

OS: Linux

g++ compiler

Installation

git clone https://github.com/hzhu007/rshell.git
cd rshell
git checkout hw0
make
bin/rshell

##Test cases # test comment # test a wrong command hahaha # test one command: ls # test comment after a command ls#ls ls # ls # test with one parameter: ls -a # test with one parameter and a wrong flag ls -hahaha # test with one parameter and spaces : ls -l # test with two parameters: ls -a -l ls -al # test with three parameters: ls -a -l -h ls -alh # test ; ls;ls ls;;;ls;;;;pwd ls; ;; ;; ;;;;;ls -a; # test && ls && ls -a wrong && ls && &&&& ls&&&&ls ls&&wrong&&ls &&& ls && ls # test || ls||pwd wrong || pwd pwd || wrong || |||| ||| pwd || ls || pwd # test combination ls -a; echo hello && echo world || pwd; git status # test commented exit #exit # test spaces before commented exit #exit # regular exit exit # rshell is back up when this is run # test exit appended with invalid input exitwqew # test exit with parameters exit --flag -a num 123

Known bugs

When exit appears after a connector with spaces before it, it doesn't work properly. For example, when input ls; exit only ls will be executed and rshell won't exit.