TH WAIT 2
SH NAME
wait \- wait for a process to exit
SH SYNOPSIS
B #include <u.h>
br
B #include <libc.h>
PP
B
int wait(Waitmsg *w)
SH DESCRIPTION
I Wait
causes a process to wait for any child process (see
IR fork (2))
to exit.
It returns the pid of a child that has exited
and fills in
I w
with more information about the child.
I W
points to a
BR Waitmsg ,
which has this structure:
IP
EX
ta 6n +\w'long 'u +\w'msg[ERRLEN]; 'u
typedef
struct Waitmsg
{
char pid[12]; /* of loved one */
char time[3*12]; /* of loved one & descendants */
char msg[ERRLEN];
} Waitmsg;
EE
PP
B Pid
is the child's
process id.
The
B time
array contains the time the child and its descendants spent in user code,
the time spent in system calls, and the child's elapsed real time,
all in units of milliseconds.
All integers in a
B Waitmsg
are formatted as right-justified textual numbers in 11-byte fields followed
by a blank.
B Msg
contains the message that the child specified in
IR exits (2).
For a normal exit,
B msg[0]
is zero,
otherwise
B msg
is
prefixed by the process name, a blank, the process id, and a colon.
PP
If there are no more children to wait for,
I wait
returns immediately, with return value \-1.
SH SOURCE
B /sys/src/libc/9syscall
SH "SEE ALSO"
IR fork (2),
IR exits (2),
the
B wait
file in
IR proc (3)
SH DIAGNOSTICS
Sets
IR errstr .
