system(3S)                     DG/UX 5.4R3.00                     system(3S)


NAME
       system - issue a shell command

SYNOPSIS
       #include <stdlib.h>

       int system (const char *string);

DESCRIPTION
       system causes the string to be given to the shell [see sh(1)] as
       input, as if the string had been typed as a command at a terminal.
       The current process waits until the shell has completed, then returns
       the exit status of the shell in the format specified by waitpid.

       If string is a NULL pointer, system checks if /sbin/sh exists and is
       executable.  If /sbin/sh is available, system returns non-zero;
       otherwise it returns zero.

       system fails if one or more of the following are true:

       EAGAIN      The system-imposed limit on the total number of processes
                   under execution by a single user would be exceeded.

       EINTR       system was interrupted by a signal.

       ENOMEM      The new process requires more memory than is allowed by
                   the system-imposed maximum MAXMEM.


   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |              point    safe  |
                     +---------+-----------------------------+
                     |system   |     N          -        -   |
                     +---------+-----------------------------+

DIAGNOSTICS
       system forks to create a child process that in turn calls exec to
       execute /sbin/sh.  This shell then executes string.  If the fork or
       exec fails, system returns a value of -1 and sets errno.

SEE ALSO
       exec(2), waitpid(2), reentrant(3).
       sh(1).











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