S
SCCS library
The directory in which Source Code Control System (SCCS) s-files and p-files are
stored.
SCCS (Source Code Control System)
A set of programs for managing program and documentation source files so that
any revision of a given file can be retrieved. Revisions to a file are stored as a
series of incremental changes (deltas) applied to the original version instead of as
complete copies of all the versions. The system provides locking mechanisms so
that only a single user can apply changes to a given file at any one time.
See also RCS (Revision Control System)
SCP (Subset Control Program)
A program that contains path specifications for all of the files related to a product
kit. The SCP is written by the kit's developer and is invoked by the setld utility
during the installation of the kit.
script
1.A nonbinary program that is interpreted and executed by a specified shell.
2. In the sed editor, a list of editing commands to be applied to the input file.
SCSI (Small Computer System Interface)
An industry-standard bus for small systems such as personal computers, small
multiuser systems, or workstations. SCSI-based devices can be configured in a
series, with multiple devices on the same bus. SCSI is pronounced scuzzy.
SCSI Interface Module
See SIM (SCSI Interface Module)
search path
A list of full pathnames (usually separated by colons) of directories to be searched
for executable files and other kinds of files. Users can create search paths by
defining variables, such as path, $PATH, and MANPATH.
security
The protection of data, system operations, and devices from accidental or
intentional ruin, damage, or exposure.
sed
The command that invokes the sed utility, the standard stream editor. The sed
editor reads one or more text files, makes editing changes according to a script of
editing commands, and writes the results to standard output.
Serial Line Internet Protocol
See SLIP (Serial Line Internet Protocol)
server
A computer system that serves one or more other computers, called clients, by
providing a resource to them.
server process
In the client/server model of communication, a process that provides services to
client processes.
See also passive user
session
See terminal session
setld
A utility for installing, managing, updating, and removing software subsets.
See also subset
sh
The command that invokes either the Bourne shell or the POSIX shell, depending
on the user setup in the passwd file.
shell
A program that interprets commands entered by the user, invoking programs and
calling for system resources as needed.
See also Bourne shell, C shell, Korn shell, POSIX shell
shell variable
TBS
See also process variable, environment variable
sign-extend
To increase the data size of an operand smaller than the computer's data path by
appending high-order bits to the operand. If the sign bit of the operand is a one,
the added bits are ones; if a zero, they are zeroes. This operation preserves the
twos-complement numerical value of the operand.
silent character
See hidden character
SIM (SCSI Interface Module)
A subprogram designed to accept CAM Control Blocks routed through the XPT
transport layer in order to execute SCSI commands.
Simple Mail Transfer Protocol
See SMTP (Simple Mail Transfer Protocol)
Simple Network Management Protocol
See SNMP (Simple Network Management Protocol)
SLIP (Serial Line Internet Protocol)
A transmission line protocol that encapsulates and transfers IP datagrams over
asynchronous serial lines. SLIP is less efficient than PPP.
See also PPP (Point-to-Point Protocol)
SMTP (Simple Mail Transfer Protocol)
The Internet standard protocol for exchanging electronic mail.
SNMP (Simple Network Management Protocol)
The Internet standard protocol for exchanging network management
information.
socket
In interprocess communications, an endpoint of communication. Also, the system
call that creates a socket and the associated data structure.
socketpair
A pair of sockets that can be created in the UNIX domain for two-way
communication. Like pipes, socketpairs require communicating processes to be
related.
See also pipe
soft link
See symbolic link
sort
To organize the information in a file into the desired order based on specifiable
criteria.
Source Code Control System
See SCCS (Source Code Control System)
source hierarchy
For building software kits, the directory tree and files that are to be compiled by
the kits command into subsets for a kit.
special file
See device special file
spooling
The process of copying files into a reserved disk area and then delivering the
temporary copies to a serially accessed device as the device becomes ready to
receive each new file. The temporary copies are delivered to the device in the
order of their creation and are deleted as their delivery is completed; hence,
spooling is a form of FIFO (first in, first out) buffering. The most common use of
spooling is for printing. Rather than require a user to wait until the printer
becomes available, the system spools the file to be printed. The user can then
edit or delete the original copy.
standard error
The file to which programs write error messages. The standard error file
(commonly called stderr) is a virtual file that is by default assigned to the user's
screen but can be reassigned (redirected) to any device or file available to the
user.
standard input
The file from which most programs receive input data or commands. The
standard input file (commonly called stdin) is a virtual file that is by default
assigned to the user's keyboard but can be reassigned (redirected) to any device
or file available to the user.
standard output
The file to which programs write output data. The standard output file (commonly
called stdout) is a virtual file that is by default assigned to the user's screen but
can be reassigned (redirected) to any device or file available to the user.
statement
An instruction in a source language, shell script, command language, and the like.
status
The state in which a program exists.
stderr
See standard error
stdin
See standard input
stdout
See standard output
store-and-forward
A type of network connection in which a complete transmission is passed to one
intermediate host before transmission to the next intermediate host begins.
stream
The TCP/IP definition developed for System V systems, and now in wide use
across UNIX systems.
stream editor
A program that manipulates the data in a text file by applying commands from a
previously prepared list called a script instead of by accepting commands from
the user. Powerful stream editors, such as the UNIX system's sed, can perform
any operation available to a full-function interactive line editor.
STREAMS
A kernel mechanism developed by AT&T that supports the implementation of
device drivers and networking protocol stacks.
See also clist, STREAMS framework
STREAMS framework
STREAMS components that define the interface standards for character I/O within
the kernel and between the kernel and user levels. These components include
functions, utility routines, kernel facilities, and data structures.
stream socket
A socket that provides two-way byte streams across a transport connection.
stty
A command that sets or reports certain characteristics of the user's terminal.
su
A command that substitutes another user's login for that of the user who invoked
the command, logging the invoking user in under the substituted login. The
invoking user must know the login password for the user whose login is being
substituted. If no other user's login is specified, the command substitutes the
root login.
subdirectory
A directory that is contained (nested) in another directory. The containing
directory is called the parent directory.
subset
A software kit module that is installed or removed with the DIGITAL UNIX setld
utility. A subset usually consists of a collection of related files, such as an
application and its support files.
subset control program
See SCP (Subset Control Program)
subset dependency
The condition in which a given subset requires the presence, or lack thereof, of
other subsets in order to function properly. Evaluated by a subset's subset control
program (SCP) under control of the setld utility.
superuser
A user possessing privileges to override the normal restrictions on file access,
process control, and so forth. A user who possesses these privileges becomes a
superuser by issuing the su command, or by logging into the system as root.
suspended
The condition of a process that is stopped but not killed. C shell, Korn shell, and
POSIX shell users have the ability to suspend and reactivate processes by using
the fg and bg commands, or by pressing Ctrl/z. A process that is suspended is
called a suspended job.
See also terminated
SVID (System V Interface Definition)
The specification that defines subroutine calls, system calls, commands, utilities,
and services under System V.
See also POSIX (Portable Operating System Interface for Computer Environments)
SVVS (System V Verification Suite)
A set of programs used to test adherence to the System V Interface Definition.
switch
Another name for an option.
See also option
symbolic link
A file that contains the pathname of another file or directory and acts as a pointer
to that file or directory. The symbolic link can occur within the same file system or
across file systems; also called a soft link.
See also hard link
sync
A command that forces all cached disk write operations to be completed before
the system is halted.
synchronous execution
A mode of execution that forces transport primitives to wait for specific events
before returning control to the transport user.
system call
Functions that access the file system and communication facilities of the kernel.
system load
The demand that all processes place on the computer. System load is usually
expressed as a number, with 1.0 representing 100 percent utilization and 0.1
representing 10 percent utilization of system resources.
System V
A version of the UNIX system developed by AT&T.
System V Interface Definition
See SVID (System V Interface Definition)
System V Verification Suite
See SVVS (System V Verification Suite)
