2.9BSD/usr/man/cat2/wait2.2j

WAIT2(2J)           UNIX Programmer's Manual            WAIT2(2J)

NAME
     wait2 - wait for process to terminate

SYNOPSIS
     #include <wait.h>

     wait2(&w.w_status, options)
     union wait w;
     int options;

     cc ... -ljobs

DESCRIPTION
     _W_a_i_t_2 is similar to the standard _w_a_i_t(2) system call, but
     allow additional options useful with job control.  They
     return the process ID of a terminated or stopped child pro-
     cess.  The _w._w__s_t_a_t_u_s and _o_p_t_i_o_n words are described by
     definitions and macros in the file <wait.h>; the union and
     its bitfield definitions and associated macros given there
     provide convenient and mnemonic access to the word of status
     returned by a _w_a_i_t_2 call.  If the call returns a process ID,
     several macros are available to interpret the status word
     returned.  If the process is stopped, WIFSTOPPED(w) is true,
     and the signal that caused it to stop is w.w_stopsig.  If
     the process is not stopped (has terminated), WIFEXITED(w)
     determines whether it terminated by calling _e_x_i_t(2); if so,
     the exit code is w.w_retcode.  WIFSIGNALED(w) is true if the
     process was terminated by a signal (see _s_i_g_n_a_l(2)); the sig-
     nal causing termination was w.w_termsig, and w.w_coredump
     indicates whether a core dump was produced.

     There are two _o_p_t_i_o_n_s, which may be combined by _o_ring them
     together.  The first is WNOHANG which causes the _w_a_i_t_2 to
     not hang if there are no processes which wish to report
     status, rather returning a pid of 0 in this case as the
     result of the _w_a_i_t_2.  The second option is WUNTRACED which
     causes _w_a_i_t_2 to return information when children of the
     current process which are stopped but not traced (with
     _p_t_r_a_c_e(2)) because they received a SIGTTIN, SIGTTOU, SIGTSTP
     or SIGSTOP signal.  See _s_i_g_s_y_s(2J) for a description of
     these signals.

RETURN VALUE
     Returns -1 if there are no children not previously waited
     for, or 0 if the WNOHANG option is given and there are no
     stopped or exited children.

ERRORS
     _W_a_i_t_2 will fail and return immediately if one or more of the
     following is true:

     [ECHILD]            The calling process has no unwaited-for

Printed 7/30/83                                                 1

WAIT2(2J)           UNIX Programmer's Manual            WAIT2(2J)

                         child processes.

     [EFAULT]            The _w._w__s_t_a_t_u_s argument points to an
                         address outside the process's allocated
                         address space.

SEE ALSO
     exit(2), fork(2), sigsys(2J), wait(2)

BUGS
     This call is peculiar to this version of UNIX.  The options
     and specifications of this system call and even the call
     itself are subject to change.  It may be replaced by other
     facilities in future versions of the system.

Printed 7/30/83                                                 2