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Annotation of cci/usr/src/man/man2/wait.2, revision 1.1.1.1

1.1       root        1: .TH WAIT 2 "27 July 1983"
                      2: .UC 4
                      3: .SH NAME
                      4: wait, wait3 \- wait for process to terminate
                      5: .SH SYNOPSIS
                      6: .ft B
                      7: .nf
                      8: #include <sys/wait.h>
                      9: .PP
                     10: .ft B
                     11: pid = wait(status)
                     12: int pid;
                     13: union wait *status;
                     14: .PP
                     15: .ft B
                     16: pid = wait(0)
                     17: int pid;
                     18: .PP
                     19: .ft B
                     20: #include <sys/time.h>
                     21: #include <sys/resource.h>
                     22: .PP
                     23: .ft B
                     24: pid = wait3(status, options, rusage)
                     25: int pid;
                     26: union wait *status;
                     27: int options;
                     28: struct rusage *rusage;
                     29: .fi
                     30: .SH DESCRIPTION
                     31: .I Wait
                     32: causes its caller to delay until a signal is received or
                     33: one of its child
                     34: processes terminates.
                     35: If any child has died since the last
                     36: .IR wait ,
                     37: return is immediate, returning the process id and
                     38: exit status of one of the terminated
                     39: children.
                     40: If there are no children, return is immediate with
                     41: the value \-1 returned.
                     42: .PP
                     43: On return from a successful 
                     44: .I wait
                     45: call, 
                     46: .I status
                     47: is nonzero, and the high byte of 
                     48: .I status
                     49: contains the low byte of the argument to
                     50: .I exit
                     51: supplied by the child process;
                     52: the low byte of 
                     53: .I status
                     54: contains the termination status of the process.
                     55: A more precise definition of the
                     56: .I status
                     57: word is given in
                     58: .RI < sys/wait.h >.
                     59: .PP
                     60: .I Wait3
                     61: provides an alternate interface for programs
                     62: which must not block when collecting the status
                     63: of child processes.  The
                     64: .I status
                     65: parameter is defined as above.  The
                     66: .I options
                     67: parameter is used to indicate the call should not block if
                     68: there are no processes which wish to report status (WNOHANG),
                     69: and/or that only children of the current process which are stopped
                     70: due to a SIGTTIN, SIGTTOU, SIGTSTP, or SIGSTOP signal should have
                     71: their status reported (WUNTRACED).  If
                     72: .I rusage
                     73: is non-zero, a summary of the resources used by the terminated
                     74: process and all its
                     75: children is returned (this information is currently not available
                     76: for stopped processes).
                     77: .PP
                     78: When the WNOHANG option is specified and no processes
                     79: wish to report status, 
                     80: .I wait3
                     81: returns a 
                     82: .I pid
                     83: of 0.  The WNOHANG and WUNTRACED options may be combined by 
                     84: .IR or 'ing
                     85: the two values.
                     86: .SH NOTES
                     87: See
                     88: .IR sigvec (2)
                     89: for a list of termination statuses (signals);
                     90: 0 status indicates normal termination.
                     91: A special status (0177) is returned for a stopped process
                     92: which has not terminated and can be restarted;
                     93: see
                     94: .IR ptrace (2).
                     95: If the 0200 bit of the termination status
                     96: is set,
                     97: a core image of the process was produced
                     98: by the system.
                     99: .PP
                    100: If the parent process terminates without
                    101: waiting on its children,
                    102: the initialization process
                    103: (process ID = 1)
                    104: inherits the children.
                    105: .PP
                    106: .I Wait
                    107: and
                    108: .I wait3
                    109: are automatically restarted when a process receives a
                    110: signal while awaiting termination of a child process.
                    111: .SH "RETURN VALUE
                    112: If \fIwait\fP returns due to a stopped
                    113: or terminated child process, the process ID of the child
                    114: is returned to the calling process.  Otherwise, a value of \-1
                    115: is returned and \fIerrno\fP is set to indicate the error.
                    116: .PP
                    117: .I Wait3
                    118: returns \-1 if there are no children not previously waited
                    119: for;  0 is returned if WNOHANG is specified and there are
                    120: no stopped or exited children.
                    121: .SH ERRORS
                    122: .I Wait
                    123: will fail and return immediately if one or more of the following
                    124: are true:
                    125: .TP 15
                    126: [ECHILD]
                    127: The calling process has no existing unwaited-for
                    128: child processes.
                    129: .TP 15
                    130: [EFAULT]
                    131: The \fIstatus\fP or \fIrusage\fP arguments point to an illegal address.
                    132: .SH "SEE ALSO"
                    133: exit(2)

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