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Ulm's Oberon Library:
SysProcess

NAME

SYNOPSIS

TYPE Event = POINTER TO EventRec;
TYPE EventRec =
   RECORD
      (Events.EventRec)
      exitcode: INTEGER;
   END;



TYPE ProcessId = INTEGER;
TYPE ProcessGroup = INTEGER;
TYPE UserId = INTEGER;
TYPE GroupId = INTEGER;
TYPE Signal = SysSignals.Signal;
TYPE Status =
   RECORD
      signal: Signal;
      exitcode: SHORTINT;
      core: BOOLEAN;
      stopped: BOOLEAN;
   END;
(* Wait4 options; see <sys/wait.h> *)
CONST nohang = 1;    (* don't hang in wait *)
CONST untraced = 2;  (* tell about stopped, untraced children *)



PROCEDURE Getpid() : ProcessId;
PROCEDURE Getpgrp() : ProcessGroup;
PROCEDURE Getppid() : ProcessId;
PROCEDURE Getuid() : UserId;
PROCEDURE Geteuid() : UserId;
PROCEDURE Getgid() : GroupId;
PROCEDURE Getegid() : GroupId;
PROCEDURE Kill(pid: INTEGER; sig: Signal;
               errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE Exit(code: INTEGER);
PROCEDURE Abort;
PROCEDURE Fork(VAR pid: ProcessId; errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE ExecEnv(path: ARRAY OF CHAR; argv, envp: SysArgs.Arguments;
                  errors: RelatedEvents.Object);
PROCEDURE Exec(path: ARRAY OF CHAR; argv: SysArgs.Arguments;
               errors: RelatedEvents.Object);
PROCEDURE Wait(VAR status: Status; VAR pid: ProcessId;
               errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE WaitFor(VAR pid: ProcessId; VAR status: Status;
                  errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE NonBlockingWait(VAR status: Status; VAR pid: ProcessId;
                          errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE NonBlockingWaitFor(VAR pid: ProcessId; VAR status: Status;
                             errors: RelatedEvents.Object) : BOOLEAN;
PROCEDURE Wait4(VAR pid: ProcessId; VAR status: Status;
                options: INTEGER;
                errors: RelatedEvents.Object;
                retry: BOOLEAN; VAR interrupted: BOOLEAN) : BOOLEAN;
PROCEDURE Pause;

DESCRIPTION

Exit causes immediate termination without raising events. Abort enforces a default reaction for SysSignals.ABRT and sends SysSignals.ABRT to the process which causes process termination (with core dump, if possible).

Getpid returns the process id, Getppid the process id of the parent process. Getpgrp returns the process group.

Getuid returns the real user id, Geteuid the effective user id of the calling process. Getgid returns the real group id, Getegid the effective group id of the calling process.

Kill sends sig to the process designated by pid. See kill(2) for details.

Fork creates a new process. pid is set to zero for the child process and to the process id of the child for the parent process. ExecEnv replaces the process image by path and passes argv and envp as command line parameters resp. environment parameters. path must be 0X-terminated. See UnixArgList for creation of argument lists. Exec is like ExecEnv but defaults envp to SysArgs.environ.

Wait waits for any child to be terminated. pid contains the process id of the terminated process and status the termination signal or the exit code. Fields of status:

____________________________________________________________________
|signal	    termination	causing	signal;	equals 0 if  terminated	 by|
|	    exit						   |
|exitcode   exit code (if signal = 0)				   |
|core	    core file produced?					   |
|stopped____stop_of_traced_process?________________________________|

Wait returns FALSE if there are no children to wait for.

WaitFor waits for the given children to terminate. The behaviour of WaitFor is modified if pid is less than 1:

____________________________________________________________________
|pid = 0    wait for any child process whose process  group  ID	 is|
|	    equal to that of the calling process.		   |
|pid = -1   wait for any child process;	the behaviour is equivalent|
|	    to Wait.						   |
|pid < 0    wait for any child process whose process  group  ID	 is|
|___________equal_to_the_absolute_value_of_pid.____________________|

NonBlockingWait and NonBlockingWaitFor are nonblocking variants of Wait and WaitFor They return FALSE and appropriate error events if no child has exited yet. Wait4 offers the most general interface to the corresponding system call. Valid options are nohang (nonblocking variant) and untraced (not only exited but also stopped children). Both options may be combined by giving nohang+untraced.

Pause suspends execution until receipt of a signal (see SysSignals) which is not ignored by the calling process. Pause does not raise an event of SysErrors in case of return.

DIAGNOSTICS

SEE ALSO

exec(2)

Exec and ExecEnv

exit(2)

Exit

fork(2)

Fork

getpid(2)

Getpid and Getppid

getpgrp(2)

Getpgrp

getuid(2)

Getuid, Geteuid, Getgid, and Getegid

kill(2)

Kill

pause(2)

Pause

ptrace(2)

trace of processes

wait(2)

Wait and Status

Process

more portable interface for exiting and aborting

SysErrors

error handling

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