Systems_Shell

Kevin Li and Peter Lee
Period 10

Features

• Forks and executes commands
• Has a nice greeting when you open the shell!
• Handles cd and exit
• Displays working directory, like bash
• Can execute multiple commands on one line separated with semicolon (";")
• Says something sad but cute when you quit shell!
• When you do something bad in the shell, it will print out bash-like errors using errno
• 'magic' can hide or show your working directory
• Implements redirect stdout

Attempted

• Handle multiple commands on one line when semicolons or commands are surrounded with spaces, like " ; " instead of just ";"
• Redirection and pipes

Bugs

• Very occasionally the parser fails and cannot read the commands correctly. We tested it, and every time it happens, it can't read a certain character and reads it as a space.
• Commands cannot be executed if there are any spaces regardless of usage of semicolons
• The redirection breaks if multiple ">"s are entered.

Files and Function Headers

main.c

shell.c

char ** parse_args(char * line, char delimiter)

• Description:
• Parses the given string using the given delimiter
• Arguments:
• char * line -> A pointer to the original string
• char delimiter -> The character that is going to be used to parse the string
• Return Value:
• A char ** which consists of the parsed strings

void exec_one(char ** args)

• Description:
• Forks off a child process and the child process calls execvp to execute the given command
• Arguments:
• char ** args -> Command line arguments that should be executed
• Return Value:
• N/A

void redir_out(char ** args)

• Description:
• Implements redirecting stdout by writing to a file
• Arguments:
• char ** args -> A pointer to the original string
• Return Value:
• N/A