Main Shell

Features

• Forks and executes commands
• Parses multiple commands on one line (separated by ;)
• Redirects using >, <
• Pipes using |
• Replaced ~ with home directory
• Exits with "exit" and SIGINT
• Changes directory with cd and recognizes nonexistent directories

Attempted

• Implementing additional redirection
• Multiple pipes were not successfully implemented
• Readline and storing history were not successfully implemented

Bugs

• Bad tokens are called for multiple pipes

Files & Function Headers

mainshell.c

• Handles all line parsing and execution

• char * strip(char * str)

  • Inputs: char * str the string
  • Returns: The stripped string
  • Description: Strips all whitespace from the start and the end of a string

• char * parse(char ** cmd, char * str, char ** parent)

  • Inputs: char ** cmd an array of commands char * str the string char ** parent a pointer to the string
  • Returns: The new value of the string
  • Description: Splits the string across semicolons

• char * verify(char * str)

  • Inputs: char * str the string
  • Returns: The bad tokens in the string
  • Description: Verifies whether or not there are bad tokens within the string

• static void sighandler(int signo)

  • Inputs: int signo the value of the signal
  • Returns: Nothing
  • Description: Checks for the exist shortcut

• void resetIO(int fd, int type)

  • Inputs: int fd standard file descriptor int type type of file - 0=stdin, 1=stdout
  • Returns: Resets stdin and stdout to original places on the file table
  • Description: Strips all whitespace from the start and the end of a string

• void resetStdIO()

  • Inputs: Nothing
  • Returns: Nothing
  • Description: Resets stdin/stdout to fd 0 and 1

• int redirect(char * redirectTo, int type)

  • Inputs: char * redirectTo loction to redirect int type type of file - 0=input, 1=output
  • Returns: The new fd of the stdin/stdout
  • Description: Redirects input depending on the given sign

• int redirCheck(char ** command, int type)

  • Inputs: char ** command pointer to commands int type type of redirection - 0="<", 1=">"
  • Returns: Index of the redirection symbol
  • Description: Checks for redirection symbol in the line

• char ** handleRedir(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: The command with NULL in place of the redirection symbol
  • Description: Redirects stdin and stdout

• int pipeCheck(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: The index of the pipe symbol
  • Description: Searches for pipe symbols in the commands

• int pipeExec(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: 1 if the function ran, 0 if it didn't
  • Description: Pipes and executes the commands

• void cd(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: Nothing
  • Description: Changes the location and current directory

• char ** convTildes(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: The command with the home path in place of the tilde
  • Description: Converts tildes to expand to the home directory path

• void execute(char ** cmd)

  • Inputs: char ** cmd pointer to commands
  • Returns: Nothing
  • Description: Forks and executes the commands