1waitid(2)                        System Calls                        waitid(2)
2
3
4

NAME

6       waitid - wait for child process to change state
7

SYNOPSIS

9       #include <wait.h>
10
11       int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options);
12
13

DESCRIPTION

15       The  waitid()  function  suspends  the calling process until one of its
16       child processes changes state. It records the current state of a  child
17       in  the   structure  pointed  to  by infop. It returns immediately if a
18       child process changed state prior to the call.
19
20
21       The idtype and  id arguments specify which  children   waitid()  is  to
22       wait for, as follows:
23
24           o      If   idtype  is  P_PID,  waitid() waits for the child with a
25                  process ID equal to (pid_t)id.
26
27           o      If idtype is P_PGID,  waitid() waits for any  child  with  a
28                  process group ID equal to (pid_t)id.
29
30           o      If  idtype  is P_ALL, waitid() waits for any child and id is
31                  ignored.
32
33
34       The options argument is used to specify which state changes waitid() is
35       to wait for. It is formed by bitwise OR operation of any of the follow‐
36       ing flags:
37
38       WCONTINUED    Return the status for any child that was stopped and  has
39                     been continued.
40
41
42       WEXITED       Wait for process(es) to exit.
43
44
45       WNOHANG       Return immediately.
46
47
48       WNOWAIT       Keep the process in a waitable state.
49
50
51       WSTOPPED      Wait  for and return the process status of any child that
52                     has  stopped upon receipt of a signal.
53
54
55       WTRAPPED      Wait for traced process(es) to become trapped or reach  a
56                     breakpoint (see ptrace(3C)).
57
58
59
60       The  infop  argument must point to a siginfo_t structure, as defined in
61       siginfo.h(3HEAD). If waitid() returns because a child process was found
62       that  satisfies  the  conditions  indicated by the arguments idtype and
63       options, then the structure pointed to by infop will be filled  by  the
64       system  with the status of the process. The si_signo member will always
65       be equal to SIGCHLD.
66
67
68       One instance of a SIGCHLD signal is queued for each child process whose
69       status  has  changed. If waitid() returns because the status of a child
70       process is available and WNOWAIT was  not  specified  in  options,  any
71       pending  SIGCHLD  signal  associated  with the process ID of that child
72       process is discarded. Any other pending SIGCHLD signals remain pending.
73

RETURN VALUES

75       If waitid() returns due to a change of state of one of its children and
76       WNOHANG  was  not  used,  0 is returned.  Otherwise, −1 is returned and
77       errno is set to indicate the error. If WNOHANG  was  used,   0  can  be
78       returned  (indicating  no error); however, no children may have changed
79       state if info->si_pid is 0.
80

ERRORS

82       The waitid() function will fail if:
83
84       ECHILD    The set of processes specified by idtype and id does not con‐
85                 tain any unwaited processes.
86
87
88       EFAULT    The infop argument points to an illegal address.
89
90
91       EINTR     The waitid() function was interrupted due to the receipt of a
92                 signal by the calling process.
93
94
95       EINVAL    An invalid value was specified for options, or idtype and  id
96                 specify an invalid set of processes.
97
98

USAGE

100       With  options  equal  to  WEXITED | WTRAPPED, waitid() is equivalent to
101       waitpid(3C). With idtype equal to P_ALL and options equal to WEXITED  |
102       WTRAPPED, waitid() is equivalent to wait(3C).
103

ATTRIBUTES

105       See attributes(5) for descriptions of the following attributes:
106
107
108
109
110       ┌─────────────────────────────┬─────────────────────────────┐
111       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
112       ├─────────────────────────────┼─────────────────────────────┤
113       │Interface Stability          │Standard                     │
114       ├─────────────────────────────┼─────────────────────────────┤
115       │MT-Level                     │Async-Signal-Safe            │
116       └─────────────────────────────┴─────────────────────────────┘
117

SEE ALSO

119       Intro(2),    exec(2),   exit(2),   fork(2),   pause(2),   sigaction(2),
120       ptrace(3C),  signal(3C),   siginfo.h(3HEAD),   wait(3C),   waitpid(3C),
121       attributes(5), standards(5)
122
123
124
125SunOS 5.11                        9 Jun 2004                         waitid(2)
Impressum