| 1 | .TH wait 3 |
| 2 | .SH NAME |
| 3 | wait \- check child process status |
| 4 | .SH SYNTAX |
| 5 | .B #include <wait.h> |
| 6 | |
| 7 | int \fBwait_nohang\fP(&\fIwstat\fR); |
| 8 | .br |
| 9 | int \fBwait_stop\fP(&\fIwstat\fR); |
| 10 | .br |
| 11 | int \fBwait_stopnohang\fP(&\fIwstat\fR); |
| 12 | .br |
| 13 | int \fBwait_pid\fP(&\fIwstat\fR,\fIpid\fR); |
| 14 | |
| 15 | int \fBwait_exitcode\fP(\fIwstat\fR); |
| 16 | .br |
| 17 | int \fBwait_crashed\fP(\fIwstat\fR); |
| 18 | .br |
| 19 | int \fBwait_stopped\fP(\fIwstat\fR); |
| 20 | .br |
| 21 | int \fBwait_stopsig\fP(\fIwstat\fR); |
| 22 | |
| 23 | int \fIpid\fR; |
| 24 | .br |
| 25 | int \fIwstat\fR; |
| 26 | .SH DESCRIPTION |
| 27 | .B wait_nohang |
| 28 | looks for zombies (child processes that have exited). |
| 29 | If it sees a zombie, |
| 30 | it eliminates the zombie, |
| 31 | puts the zombie's exit status into |
| 32 | .IR wstat , |
| 33 | and returns the zombie's process ID. |
| 34 | If there are several zombies, |
| 35 | .B wait_nohang |
| 36 | picks one. |
| 37 | If there are children but no zombies, |
| 38 | .B wait_nohang |
| 39 | returns 0. |
| 40 | If there are no children, |
| 41 | .B wait_nohang |
| 42 | returns -1, |
| 43 | setting |
| 44 | .B errno |
| 45 | appropriately. |
| 46 | |
| 47 | .B wait_stopnohang |
| 48 | is similar to |
| 49 | .BR wait_nohang , |
| 50 | but it also looks for children that have stopped. |
| 51 | |
| 52 | .B wait_stop |
| 53 | is similar to |
| 54 | .BR wait_stopnohang , |
| 55 | but if there are children it will pause waiting for one of them |
| 56 | to stop or exit. |
| 57 | |
| 58 | .B wait_pid |
| 59 | waits for child process |
| 60 | .I pid |
| 61 | to exit. |
| 62 | It eliminates any zombie that shows up in the meantime, |
| 63 | discarding the exit status. |
| 64 | |
| 65 | .B wait_stop |
| 66 | and |
| 67 | .B wait_pid |
| 68 | retry upon |
| 69 | .BR error_intr . |
| 70 | .SH "STATUS PARSING" |
| 71 | If the child stopped, |
| 72 | .B wait_stopped |
| 73 | is nonzero; |
| 74 | .B wait_stopsig |
| 75 | is the signal that caused the child to stop. |
| 76 | |
| 77 | If the child exited by crashing, |
| 78 | .B wait_stopped |
| 79 | is zero; |
| 80 | .B wait_crashed |
| 81 | is nonzero. |
| 82 | |
| 83 | If the child exited normally, |
| 84 | .B wait_stopped |
| 85 | is zero; |
| 86 | .B wait_crashed |
| 87 | is zero; |
| 88 | and |
| 89 | .B wait_exitcode |
| 90 | is the child's exit code. |
| 91 | .SH "SEE ALSO" |
| 92 | wait(2), |
| 93 | error(3) |