Chapter 44, Pipes and FIFOs

• ls -alrt | more
• Pipes and FIFOs are a basic inter-process communications mechanism.
• The are fairly primitive
  • One way communication (but you can make two)
  • No message separation
  • Limited size
• mkfifo
  • Make a file system pipe.
  • This is one of the different file types (regular files, directories, FIFOs (pipes))
  • Do this.
  • counter > apipe
  • talker < apipe
• pipe
  • Needs unistd.h
  • int pipe(int fildes[2]);
    • Parameters
      • fildes is an array of file descriptors
      • fildes[0] is the read end of the pipe.
      • fildes[1] is the write end of the pipe.
      • writer ---> fildes[1] ----> filedes[0] ----> reader
    • Return value
      • 0 on success
      • -1 on error
• dup
  • needs unistd.h
  • int dup(int oldfd);
    • Creates a copy of oldfd at the next available file descriptor.
  • int dup2(int oldfd, int newfd);
    • Copies oldfd to newfd, closing newfd in required.
• Look at piper.C
• He gives several other examples.