A simple Unix shell written in C++.

Written by Will Taylor and James Stewart for our Operating Systems course at Texas Christian University.

• Internal commands:
  • help Displays a list of internal commands with their descriptions
  • cd DIRECTORY Switches the current working directory to DIRECTORY.
  • history Displays a list of the last 10 executed user commands
  • !! Executes the most recent command in the history
  • !N If N is a positive integer, the Nth command in the history queue is executed
  • alarm N Where N is a positive integer, an alarm is set that will go off in N seconds. Only one alarm may be set at one time. If N=0, then any previously set alarm will be canceled.
  • exit or quit Terminates the BlueShell application
• Processes are initiated by forking a child process using the fork syscall.
• Backgrounding of processes is allowed by placing & after the command.
• I/O redirection: I/O redirection is implemented with the dup2 syscalls (cmd0 >> cmd1) or (cmd0 << cmd1).
• Piping: single piping is allowed by using (cmd0 | cmd1). Implemented with dup2 and pipe syscalls.