Process Control and Management

A process is basically a single running program. It may be a ``system'' program (e.g login, update, csh) or program initiated by the user (textedit, dbxtool or a user written one).

When UNIX runs a process it gives each process a unique number - a process ID, pid.

The UNIX command ps will list all current processes running on your machine and will list the pid.

The C function int getpid() will return the pid of process that called this function.

A program usually runs as a single process. However later we will see how we can make programs run as several separate communicating processes.

• Running UNIX Commands from C
  • execl()
  • fork()
  • wait()
  • exit()
• Piping in a C program
  • popen() - Formatted Piping
  • pipe() - Low level Piping
• Interrupts and Signals
  • Sending Signals - kill()
  • Receiving signals - signal()