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資訊系統原理作業二補充說明

資訊系統原理作業二補充說明. fork() – create a child process #include <sys/types.h> #include <unistd.h> pid_t fork(void) Returns: 0 in child process ID of child (>0) in parent -1 on error. fork(). A Simple Example: … pid_t pid = fork (); if (pid<0 ) /* error */ { … }

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資訊系統原理作業二補充說明

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  1. 資訊系統原理作業二補充說明 • fork() – create a child process • #include <sys/types.h> • #include <unistd.h> • pid_t fork(void) • Returns: • 0 in child • process ID of child (>0) in parent • -1 on error

  2. fork() • A Simple Example: … pid_t pid = fork(); if (pid<0) /* error */ { … } else if (pid == 0) /* child */ { … } else /* parent */ { … } …

  3. Pipe (1/2) • Pipes: • The oldest (and most commonly used) form of UNIX IPC (Inter-Process Communication) • half-duplex (data flows only in one direction) • Can be used only between processes that have a common ancestor

  4. Pipe (2/2) • pipe() – Create a pipe • #include <unistd.h> • int pipe(int fd[2]); • Returns: 0 if OK, -1 on error. • fd[0]: for reading, fd[1]: for writing • Close unnecessary fds • Read(fd[0]) • Write(fd[1])

  5. References • Advanced Programming in the UNIX Environment, by W. Richard Stevens, Addison-Wesley. • Manual pages on UNIX systems: • man fork • man pipe

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