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system(3)
NAME
  system - Execute a shell command

SYNOPSIS
  #include <stdlib.h>

  int system(
	  const char *string );

LIBRARY
  Standard C Library (libc)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  system():  XPG4, XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  string
      Specifies a valid sh shell command.

      If string is NULL (0), the system() function tests the accessibility of
      the sh command interpreter.

      If string is not NULL, the system() function passes the parameter to
      the sh command, which interprets string as a command and executes it.

DESCRIPTION
  The system() function passes the string parameter to the sh command, which
  interprets string as a command and executes it. See sh(1) to determine
  which command interpreter is defined by sh on your system.

  The system() function invokes the fork() function to create a child process
  that in turn uses theexec function to run sh, which interprets the shell
  command contained in the string parameter. The current process waits until
  the shell has completed before returning.

RETURN VALUES
  If the string parameter is NULL, the system() function returns 0 if it is
  unable to access the command interpreter or a non-zero value if sh is
  accessible.

  If the string parameter is not NULL, upon successful completion by sh, the
  system() function returns the exit status of the shell process in the form
  that wait(2) returns. Otherwise, the system() function returns a value of
  -1 and sets errno to indicate the error.

  Exit status 127 indicates that the shell could not be executed.

  Note that the exit status should only be interpreted using the macros
  described in wait(2) and defined in thesys/wait.h header file.

ERRORS
  The system() function sets errno to the specified values for the following
  conditions:

  [ECHILD]
      The status of the child process created by system() is no longer
      available.

  In addition, the system() function may set errno values as described by
  fork().

SEE ALSO
  Functions: exec(2), exit(2), fork(2), wait(2)

  Commands: sh(1)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for S

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