AT&T UNIX™PC Unix System V Users Manual - tenox

INTR0 ( 2 ) INTR0 ( 2 )
35 ENOMSG No message of desired type
An attempt was made to receive a message of a type that
does not exist on the specified message queue; see
msgop (2).
36 EIDRM Identifier Removed
This error is returned to processes that resume execution
due to the removal of an identifier from the file system's -�
name space (see msgctl(2), semctl(2), and shmctl(2)).
DEFINITIONS
Process ID
Each active process in the system is uniquely identified by a positive
integer called a process ID. The range of this ID is from 0 to
30,000.
Parent Process ID
A new process is created by a currently active process; see fork(2).
The parent process ID of a process is the process ID of its creator.
Process Group ID
Each active process is a member of a process group that is
identified by a positive integer called the process group ID. This
ID is the process ID of the group leader. This grouping permits the
signaling of related processes; see kill(2).
Tty Group ID
Each active process can be a member of a terminal group that is
identified by a positive integer called the tty group ID. This
grouping is used to terminate a group of related process upon termination
of one of the processes in the group; see exit(2) and signal(2).
Real User ID and Real Group ID
Each user allowed on the system is identified by a positive integer
called a real user ID.
Each user is also a member of a group. The group is identified by
a positive integer called the real group ID.
An active process has a real user ID and real group ID that are set
to the real user ID and real group ID, respectively, of the user
responsible for the creation of the process.
Effective User ID and Effective Group ID
An active process has an effective user ID and an effective group ID
that are used to determine file access permissions (see below). The
effective user ID and effective group ID are equal to the process's
real user ID and real group ID respectively, unless the process or
one of its ancestors evolved from a file that had the set-user-ID bit
or set-group ID bit set; see exec(2).
Super-user
A process is recognized as a super-user process and is granted special
privileges if its effective user ID is 0.
Special Processes
The processes with a process ID of 0 and a process ID of 1 are special
processes and are referred to as procO and proc1.
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