system(3c) - osol9

1system(3C)               Standard C Library Functions               system(3C)
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NAME

6       system - issue a shell command
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SYNOPSIS

9       #include <stdlib.h>
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11       int system(const char *string);
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DESCRIPTION

15       The  system() function causes string to be given to the shell as input,
16       as if string had been typed as a command at  a  terminal.  The  invoker
17       waits  until  the  shell has completed, then returns the exit status of
18       the shell in the format specified by waitpid(3C).
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21       If string is a null pointer, system() checks if the shell exists and is
22       executable.   If  the  shell  is available, system() returns a non-zero
23       value; otherwise, it returns 0.  The standard to which the caller  con‐
24       forms determines which shell is used. See standards(5).
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27       The  system()  function  sets  the  SIGINT  and  SIGQUIT  signals to be
28       ignored, and blocks the SIGCHLD signal for the  calling  thread,  while
29       waiting  for  the  command to terminate. The system() function does not
30       affect the termination status of any child  of  the  calling  processes
31       other than the process it creates.
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34       The  termination status of the process created by the system() function
35       is not affected by the actions of other threads in the calling  process
36       (it is invisible to wait(3C)) or by the disposition of the SIGCHLD sig‐
37       nal in the calling process, even if it is set to be ignored. No SIGCHLD
38       signal  is  sent  to the process containing the calling thread when the
39       command terminates.
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RETURN VALUES

42       The system()  function  executes  posix_spawn(3C)  to  create  a  child
43       process running the shell that in turn executes the commands in string.
44       If posix_spawn() fails, system() returns −1 and sets errno to  indicate
45       the error; otherwise the exit status of the shell is returned.
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ERRORS

48       The  system() function may set errno values as described by fork(2), in
49       particular:
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51       EAGAIN    A resource control or  limit on the  total  number  of   pro‐
52                 cesses,  tasks  or  LWPs  under  execution  by a single user,
53                 task,  project, or  zone has  been  exceeded,  or  the  total
54                 amount  of  system  memory available  is temporarily insuffi‐
55                 cient to duplicate this process.
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58       ENOMEM    There is not enough swap space.
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61       EPERM     The  {PRIV_PROC_FORK}  privilege  is   not  asserted  in  the
62                 effective set of the calling process.
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USAGE

66       The  system()  function  manipulates the signal handlers for SIGINT and
67       SIGQUIT. It is therefore not safe to call system() in  a  multithreaded
68       process, since some other thread that manipulates these signal handlers
69       and a thread that concurrently calls system() can interfere  with  each
70       other  in  a  destructive manner.  If, however, no such other thread is
71       active, system()  can  safely  be  called  concurrently  from  multiple
72       threads.  See  popen(3C) for an alternative to system() that is thread-
73       safe.
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ATTRIBUTES

76       See attributes(5) for descriptions of the following attributes:
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81       ┌─────────────────────────────┬─────────────────────────────┐
82       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
83       ├─────────────────────────────┼─────────────────────────────┤
84       │Interface Stability          │Standard                     │
85       ├─────────────────────────────┼─────────────────────────────┤
86       │MT-Level                     │Unsafe                       │
87       └─────────────────────────────┴─────────────────────────────┘
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