UNIX Shell

Execution

make
./shell

Features

• Shell prompt is displayed as <username@hostname:PWD>. PWD is displayed relative to HOME directory, which is set as the directory in which the shell is initially started.
• Semi-colon separated list of commands
• Input/Output Redirection & Piping
• Background/Foreground processes
• Signal Handling

Commands implemented:

• pwd : returns present working directory
• cd [PATH] : changes current working directory to the specified directory, if it exists. Otherwise, error is shown
• echo : Displays a string on the console.
• ls [OPTIONS] [PATH] : displays information about the directory specified in PATH, if it exists, or about the PWD.
  Options:
  • -l : displays detailed information
  • -a : displays hidden files
• pinfo [PID] : displays process information about the shell's process, or PID if specified
• nightswatch -n [seconds] [command]: Periodically executes one of the two commands("dirty","interrupts") every n seconds. Press 'q' to exit.
• setenv [VAR] [value] : Sets value of environment variable VAR to value. If variable does not exist, it is created and initialised.
• unsetenv [VAR] : destroys the environment variable VAR
• jobs : prints a list of all currently running jobs
• kjob [jobNumber] [signalNumber] : takes the job id of a running job and sends a signal value to that process
• fg [jobNumber] : brings a running or a stopped background job with given job number to foreground.
• bg [jobNumber] : changes a stopped background job to a running background job.
• overkill : kills all background process at once.
• quit : exits the shell
• All other commands can be executed by forking parent process.