HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

p
glossary(9) glossary(9)
pipe An interprocess I/O channel used to pass data between two processes. It is commonly
used by the shell to transfer data from the standard output of one process to the stan-
dard input of another. On a command line, a pipe is signaled by a vertical bar (
|). Out-
put from the command to the left of the vertical bar is channeled directly into the stan-
dard input of the command on the right.
portable file name character set
The following set of graphical characters are portable across conforming implementations
of IEEE Standard P1003.1:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
abcdefghijklmnopqrstuvwxyz
01234567890._-
The last three characters are the dot, underscore and hyphen characters, respectively.
The hyphen should not be used as the first character of a portable file name.
position-independent code (PIC)
Object code that can run unmodified at any virtual address. Position-independent code
can use PC-relative addressing modes and/or linkage tables. It is most often used in
shared libraries, in which case the linkage tables are initialized by the dynamic loader.
Position-independent code is generated when the
+z or +Z compiler option is specified.
privileged groups
A privileged group is a group that has had a
setprivgrp (see getprivgrp (2)) opera-
tion performed on it, giving it access to some system calls otherwise reserved for the
superuser. See appropriate privileges.
process An invocation of a program, or the execution of an image (see image). Although all com-
mands and utilities are executed within processes, not all commands or utilities have a
one-to-one correspondence with processes. Some commands (such as cd) execute within a
process, but do not create any new processes. Others (such as in the case of
ls|wc
-l) create multiple processes. Several processes can be running the same program, but
each can be different data and be in different stages of execution. A process can also be
thought of as an address space and single thread of control that executes within that
address space and its required system resources. A process is created by another pro-
cess issuing the fork(2) function. The process that issues fork(2) is known as the parent
process and the new process created by the fork(2) as the child process.
process 1 See
init.
process group
Each process in the system is a member of a process group. This grouping permits the
signaling of related processes. A newly created process joins the process group of its
creator.
process group ID
Each process group in the system is uniquely identified during its lifetime by a process
group ID, a positive integer less than or equal to
PIC_MAX.Aprocess group ID can-
not be reused by the system until the process group lifetime ends.
process group leader
A process group leader is a process whose process ID is the same as its process group
ID.
process group lifetime
A period of time that begins when a process group is created and ends when the last
remaining process in the group leaves the group, either due to process termination or by
calling the setsid (2) or setpgid (2) functions.
process ID Each active process in the system is uniquely identified during its lifetime by a positive
integer less than or equal to
PID_MAX called a process ID. A process ID cannot be
reused by the system until after the process lifetime ends. In addition, if there exists a
process group whose process group ID is equal to that process ID, the process ID cannot
be reused by the system until the process group lifetime ends. A process that is not a sys-
tem process shall not have a process ID of 1.
process lifetime
After a process is created with a fork(2) function, it is considered active. Its thread of
Section 9−−16 Hewlett-Packard Company − 15 − HP-UX 11i Version 2: August 2003