stdlib/system.3

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  36 .\"     @(#)system.3    8.1 (Berkeley) 6/4/93
  37 .\" $FreeBSD: src/lib/libc/stdlib/system.3,v 1.11 2002/05/27 03:45:27 dd Exp $
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  39 .Dd June 4, 1993
  40 .Dt SYSTEM 3
  41 .Os
  42 .Sh NAME
  43 .Nm system
  44 .Nd pass a command to the shell
  45 .Sh LIBRARY
  46 .Lb libc
  47 .Sh SYNOPSIS
  48 .In stdlib.h
  49 .Ft int
  50 .Fn system "const char *command"
  51 .Sh DESCRIPTION
  52 The
  53 .Fn system
  54 function
  55 hands the argument
  56 .Fa command
  57 to the command interpreter
  58 .Xr sh 1 .
  59 The calling process waits for the shell
  60 to finish executing the command,
  61 ignoring
  62 .Dv SIGINT
  63 and
  64 .Dv SIGQUIT ,
  65 and blocking
  66 .Dv SIGCHLD .
  67 .Pp
  68 If
  69 .Fa command
  70 is a
  71 .Dv NULL
  72 pointer,
  73 .Fn system
  74 will return non-zero if the command interpreter
  75 .Xr sh 1
  76 is available, and zero if it is not.
  77 .Pp
  78 The
  79 .Fn system
  80 function
  81 returns the exit status of the shell as returned by
  82 .Xr waitpid 2 ,
  83 or \-1 if an error occurred when invoking
  84 .Xr fork 2
  85 or
  86 .Xr waitpid 2 .
  87 A return value of 127 means the execution of the shell
  88 failed.
  89 .Sh SEE ALSO
  90 .Xr sh 1 ,
  91 .Xr execve 2 ,
  92 .Xr fork 2 ,
  93 .Xr waitpid 2 ,
  94 .Xr popen 3
  95 .Sh STANDARDS
  96 The
  97 .Fn system
  98 function
  99 conforms to
 100 .St -isoC
 101 and is expected to be
 102 .St -p1003.2
 103 compatible.