saved user ID --
(programming)
The saved user ID and saved group ID
are the values of the effective user ID
and effective group ID
prior to an
exec(2)
of a file.
scalability --
A computer's ability to increase system capacity linearly with
each additional CPU.
schedule --
To assign resources (main store and CPU time) to processes.
scheduler --
A permanent process (with process number 0 and associated kernel
facilities) that determines the order in which various processes are executed.
scohelp --
See
help.
screen --
A display device on which the user views or enters specific information.
script --
(programming)
A file which contains the definition of a
frame (a frame definition file),
the definition of global
attributes of an FMLI application
(an initialization file),
the definitions of application-specific
commands (a commands file),
a list of aliases for pathnames
(an alias file), or shell commands.
scroll --
To change your viewpoint in a window or file,
either vertically or horizontally,
thus displaying information that is not currently visible.
scroll bars --
The sliding controls located on the right or bottom of some windows,
which you move to scroll through the window contents.
scroll indicators --
(programming)
Symbols contained in the scroll box of FMLI frames to
indicate that additional material is available above or below the
current frame borders.
The up symbol is a caret ``^'' or up-arrow character, and the down
indicator is a ``v'' or down-arrow character.
scrolling --
(programming)
An attribute of FMLI frames which allows a fixed-size
frame to accommodate a larger amount of information than can be
displayed in it at one time.
The first frameful of information is displayed when the
frame is opened, and users can press named
keys or their alternate keystrokes to move forward to a new frameful of
information, or to move back to a previous frameful.
SCSI (Small Computer System Interface) --
A machine-independent peripheral interface that allows you to connect
other devices to your
computer while only taking up one bus slot in your machine.
search path --
In the shell, a list of pathnames that determine the
directories in which a desired file will be sought
and the order in which they will be investigated.
The command name is prefixed with members of the
search path in turn until a pathname of an
executable file results; the search path is given by the shell
variable PATH.
secondary name server --
A host that is configured to take over
domain name server
responsibilities temporarily in case the primary name server
goes down.
secondary server --
Another name for a stratum 2 server.
See also
primary server.
secondary source window --
(programming)
When using the GUI debugger, the
secondary source window is indicated by an
asterisk (``*'') in the window header, and is
not updated when the current process stops.
Secondary source windows are created with the
New Source option.
sector --
A 512-byte portion of a track that can be accessed
by magnetic disk heads in the course of a predetermined rotational
displacement of the storage device.
security --
The collective term for tools and protocols used
to protect computer resources, primarily by limiting access to
a system, specific files, or specific processes.
segment --
A contiguous address space range of a process
with consistent read, write, and execute capabilities.
For example, three common segments are the
text segment, containing read-only instructions and data;
the data segment, containing static
data that is explicitly initialized;
and the bss segment, containing static data
that is initialized to zero.
select --
To choose a menu item, list item, or an icon by clicking on
it with mouse button 1.
select button --
See
mouse button.
Selection Mechanism --
(programming)
The primary mechanism that X11 defines for clients that
want to exchange information.
Refer to both Xlib and
Inter-Client Communication Manual (ICCCM, [5])
documents for more details.
semantic processing --
(programming)
Semantic processing entails input validation of the
characters received from a
character device.
semaphore --
An IPC facility which allows two or
more processes to be synchronized.
semaphore identifier --
(programming)
A semaphore identifier (semid) is a unique positive
integer created by a
semget(2)
system call.
Each semid has a set of semaphores and a data structure
associated with it.
serializing --
(programming)
Converting data from a machine-specific representation
to XDR format.
serial port --
A physical connector on the computer that can be used to establish an
asynchronous link to a serial device, such as a modem, mouse, or printer.
serial printer --
Any printer connected to a serial port (for example, COM1 or COM2) on your
computer.
server mode --
1. SCOhelp mode when scohelp
is started by asking for help from another tool or
application. See also
standalone mode
and
help server mode.
2. (programming) The transport user in connection-mode
that offers services to other users (clients) and enables
these clients to establish a transport connection to it.
3. The mode in which a time server allows itself to be polled
by a host (the client) that wants to synchronize with it.
In this mode, if the time server polls the client to try to
synchronize with it, the client does not respond. In this
case, the client is said to operate in
client mode.
server process --
A process that receives directives from a caller
process to execute procedures locally.
service identifier --
A string supplied by an administrative command when it requests a
remote operation primitive that associates the primitive with
administrative services. A service identifier determines default file
locations in the remote administration directory structure.
service indication --
(programming)
The notification of a pending event generated by the provider to
a user of a particular service.
service primitive --
(programming)
The unit of information passed across a service interface that
contains either a
service request
or
service indication.
service request --
(programming)
A request for some action generated by a user to the provider
of a particular service.
session --
(programming)
A group of processes identified by a common
ID, called a ``session ID'', capable
of establishing a connection
with a controlling terminal.
Any process that is not a process group leader
can create a new session
and process group, becoming the session leader
of the session and process
group leader of the process group.
A newly created process joins the
session of its creator.
session ID --
(programming)
Each session in the system is uniquely identified
during its lifetime by a positive integer called a
session ID, the process ID
of its session leader.
session leader --
(programming)
A session leader is a process whose session ID
is the same as its process and process group ID.
session lifetime --
(programming)
A session lifetime begins when the session is created by its session
leader, and ends when the lifetime of the last process that is a member
of the session ends, or when the last process that is a member in the
session leaves the session.
set --
An SNMP operator. For each variable contained in the
SetRequestPDU, the named instance is identified. If the
named instance doesn't exist, or the instance doesn't allow writing, or
the value supplied in the request is syntactically incorrect or
contains an out-of-range value,
a GetResponsePDU is returned with an
appropriate error code. Otherwise, all the variables are written
simultaneously and a GetResponsePDU is issued.
share --
The action a server machine performs to allow some or all of its resources
to become available to other hosts.
shared memory --
An IPC facility that allows two or more
processes to share the same data space.
shared memory identifier --
(programming)
A shared memory identifier (shmid)
is a unique positive integer created by a
shmget(2)
system call.
Each shmid has a segment of memory
(referred to as a ``shared memory segment'')
and a data structure associated with it.
(Note that these shared memory segments
must be explicitly removed by the user
after the last reference to them is removed.)
shared object --
(programming)
A shared object, or ``dynamically linked library'', is a single
object file that contains the code for every function in the library.
When you call a library function in your program,
and specify a dynamic linking option on the
cc(1)
command line, the entire contents of the shared object
are mapped into the virtual address space of your process at run time.
As its name implies, a shared object contains code
that can be used simultaneously by different programs at run time.
shared text --
Shared text is a text segment, one copy of which
can be used simultaneously by more than one process.
shell --
A program that controls how the user interacts with
the operating system. Using such programs, you can write
a
shell script
to automate work you do regularly. The shells available
system include the
Korn shell,
the
Bourne shell,
and the
C shell.
shell escape --
A command you type from within an interactive program to escape to the
shell.
In
vi(1),
you can type :!command
to escape to the shell and execute command. When
command has finished executing, you return
to the editor. You can start a new shell this way with
:!sh, for example. To exit this subshell and
return to the editor, press <Ctrl>D or type
exit.
shell programming language --
A programming language that is built into the
shell.
The
Korn shell,
the
Bourne shell,
and the
C shell
all have slightly different
programming languages but all three shells offer basics
such as variable creation, loops, and conditional tests.
shell script --
An executable text
file
written in a
shell programming language.
Scripts are made up of shell programming commands mixed
with regular UNIX system commands. To run a shell script,
you can change its
permissions
to make it an executable file, or you can use it as the
argument
to a shell
command line
(for example, sh script). The
shell
running the script reads it one line at a time and
performs the requested commands.
shell variable --
A
variable
associated with a
shell script.
shuffle --
To move a window up or down through a stack of open windows
on
your screen.
signal --
A software interrupt generated within the kernel,
which
causes the current process to terminate unless a
trap
was set to catch the signal. Several different signals are
available, which serve different purposes.
signal event --
(programming)
When using the GUI debugger, the
signal event suspends the process and performs
the associated commands whenever the process
receives the specified signal.
Multiple events can be created for the same signal.
simplified interface --
(programming)
The simplest level of the RPC package.
single-user --
A system state in which only one user is supported.
skew --
A measure, in Hertz, of the difference between the actual
frequency of a
clock and what its frequency should be to keep perfect
time. See also
drift.
slew --
To adjust the time of a clock gradually until it tells the
correct time. Compare with
step.
slice --
A portion of a partition on your hard disk that contains
a separate filesystem.
See also
partition.
SLIP --
Serial Line Internet Protocol,
a simple protocol for framing IP datagrams
for transmission over serial links.
smart host --
A computer that has more complete information about
the entire mail network than do local hosts. Mail
addressed to hosts or users unknown to a local host can be
forwarded to the smart host.
See also
badhost/baduser
for information about badhosts/badusers.
SMTP --
Simple Mail Transfer Protocol,
the mail transfer protocol used over TCP/IP and the
Internet.
SMUX -- SNMP multiplexing. SMUX is a vendor-independent protocol that defines a mechanism for communcation between an SNMP agent and multiple user daemons, called SMUX peers. See also SNMP.
snap to grid --
To force the area of the workspace being viewed to
correspond to the nearest work area marked out by the
grid.
SNMP --
Simple Network Management Protocol,
the Internet protocol used to monitor and control devices and networks
manufactured by multiple vendors.
source --
(programming)
The starting point of the drag-and-drop operation.
It is also referred to as the ``holder''.
source file --
1. Source files contain the programming language version of a program.
Before a computer can execute the program,
the source code must be translated by a compiler and assembler
into the machine language of the computer.
See also
object file.
2. The uncompiled version of a program.
3. Generally, the unprocessed version of a file.
SOutPDU --
A type of Protocol Data Unit sent by an SNMP
agent
to an SMUX
peer
to initiate the second phase of a set operation.
An
SOutPDU
can be either of two types:
``commit'' or ``rollback''. A commit SOutPDU instructs
the peer to proceed with writing the new pending values to the variables in the
SetRequestPDU. A rollback SOutPDU instructs
the peer to forget the new pending
values for the variables in the SetRequestPDU and to
leave the existing values intact.
special file --
An inode that designates a device,
further categorized as either a block
special file describing a
block device, or a character special file describing
a character device.
special processes --
(programming)
The process with ID 0 and the process with ID 1
are special processes referred to as
``proc0'' and ``proc1''; see
kill(2).
proc0 is the process scheduler.
proc1 is the initialization process
(init);
proc1 is the ancestor of every other
process in the system and is used to
control the process structure.
spoofing --
The act of creating a hoax on a computer system,
usually with malicious intent.
A typical instance of spoofing is a
program that appears to be the login
program and tricks the user into supplying a password.
spool --
To collect and serialize output from multiple processes
competing for a single output service.
spool area --
A directory in which a spooler collects work.
spooler --
A daemon that spools.
spreadsheet --
A collection of information arranged in rows and columns.
Typical uses for spreadsheets include balancing income
versus debits, preparing taxes, and performing data
analysis.
SPX --
Sequenced Packet eXchange, a protocol that enhances the IPX
protocol by providing reliable delivery.
See also
IPX (Internetwork Packet eXchange protocol).
stack --
A group of open windows, one on top of another.
standalone mode --
Standalone or standalone mode refers to scohelp
when started from a command line with the
command scohelp.
See also
server mode
and
help server mode.
standard input --
The usual place from which a program takes its input. By
default, this is the keyboard. Standard input can be
redirected; for example, you can use the less-than symbol
(<) to instruct a program to take input from a file.
Also known as stdin, the standard input is identified by
the
file descriptor
0.
standard output --
The usual place where a program writes its output.
By default, this is the screen. Standard output can be
redirected; for example, you can use a pipe symbol (|) to
instruct a program to write its output into a
pipe,
which will then be read as input by the next program in the
pipeline. Also known as stdout, the standard output is
identified by the
file descriptor
1.
static data --
(programming)
Static represents a condition persistent throughout a process.
Static data occupies the data segment and the bss segment.
static linking --
(programming)
Static linking refers to the process in
which external references in a
program are linked with their definitions
when an executable is created.
stay-up menu --
(programming)
A menu that was brought up and made to stay
on the screen for one round of use.
The controls in this menu behave like
controls in an unpinned command window,
except that the menu is removed from the
screen even if nothing is selected from the menu.
stdio --
standard I/O, a library of efficient and
portable I/O routines;
the header file contains definitions and declarations. See also
stdio(3S).
step --
To change the time of a clock to the correct time with no
intermediate adjustments. Compare with
slew.
sticky bit --
A permission flag that identifies a file as a sticky file.
sticky file --
A special permission for a shared text file that causes a copy of the
text segment to be retained in the swap area to improve system response.
stop event --
(programming)
When using the GUI debugger, a stop
event suspends the process and performs
the associated commands, if any, whenever the
specified condition in the program's address
space becomes true.
stop expression --
(programming)
When using the GUI debugger, stop expressions are
special expressions accepted by the stop command.
The expression may include
one or more of location, (expression),
or *lvalue,
joined by the special ``&&'' (and) or ``||'' (or) operators.
stratum --
The distance a host running the
xntpd(1Mtcp)
time daemon is from an external source of Coordinated Universal Time
(UTC). A stratum 1 server has direct access to
an external source of UTC, such as a radio clock
synchronized to a standard time signal broadcast. In
general, a stratum n server is n-1
network hops away from a stratum 1 server. For example, a
stratum 4 server is 3 hops away from a stratum 1 server.
Also, a stratum n server is at a higher stratum
than a stratum n-1 server. For example, a
stratum 3 server is at a higher stratum than a stratum 2
server, and at a lower stratum than a stratum 4 server.
See also
time daemon.
stream --
(programming) A kernel aggregate created by connecting STREAMS
components, resulting from
an application of the STREAMS mechanism.
A stream is a full-duplex data path within the kernel
between a user process and driver routines.
The primary components are the stream head, the driver,
and zero or more pushable modules between the stream head and driver.
A stream is analogous to a shell pipeline except that
data flow and processing are bidirectional.
stream end --
(programming)
The stream end is the component of a stream farthest from the
user process, providing the interface to the device.
It contains pointers to driver (rather than module) routines.
stream head --
(programming)
In a stream, the stream head is the end of the stream
that provides the interface between the stream and a user process.
The principal functions of the stream head are processing
STREAMS-related system calls,
and passing data and information between a user
process and the stream.
STREAMS --
(programming)
A set of kernel mechanisms that support the development of
network services and data communication drivers.
It defines interface standards for character input/output
within the kernel and between the kernel and user level processes.
The STREAMS mechanism is composed of utility routines,
kernel facilities, and a set of data structures.
string --
(programming)
A string is a contiguous sequence of characters treated
as a unit. In the C language, a character string is an
array of characters terminated
by the null character.
subdirectory --
A directory that resides within another directory.
Every directory except the root directory is a
subdirectory.
subdomain --
A registered name that describes a company,
department, or any subgroup under a top-level
domain.
sco is an example of a subdomain in the domain
COM.
subject --
A process; anything that causes information to flow among objects
or that changes the system state. The initial process for a
user is the shell invoked by
login(1).
submenu --
A menu that appears when a menu item is selected.
It provides additional choices specific to the selected
item. It is also known as a cascading menu.
subnet --
An administrative division of a network into smaller networks.
subnet number --
The part of an IP address that
refers to a specific subnet.
sub-object --
(programming)
A sub-object is the equivalent of a
primitive widget
contained in a
flat widget.
In a Flat Exclusives or Flat
NonExclusives widget, the sub-objects are the equivalents of
RectButtons. In a Flat CheckBox, the sub-objects
are the equivalents of CheckBox widgets.
super-block --
The second block in a filesystem,
which describes the allocation of space in the filesystem.
See also
boot block.
superuser --
A user who has powerful special privileges needed
to help administer and maintain the system. The superuser
logs in as root.
Someone with the root password can
access and modify any
file
on the system.
surface analysis --
A hard disk test to check for defects in each disk block. Performing a surface
analysis is important to ensure that the disk does not have defects in areas
where critical data will be placed.
SVID --
System V Interface Definition, which
defines the standard interface for UNIX System V Release 4 (SVR4)
and is the basis of
other UNIX operating system standards.
swap --
To move the core image of an executing
program between main and secondary storage to make
room for other processes.
swap area --
The part of secondary store to which core images
are swapped; the swap area is disjointed from the
filesystem.
See also
swap space.
swap space --
If internal active and inactive processes fill up the memory,
the operating system automatically swaps some inactive processes
out of system memory and onto a special section of the hard
disk to allow for more memory space. The area
swapped to is known as ``swap space''.
See also
swap area
symbolic link --
A new name that refers to a directory or file that already exists.
Use this name to change to another directory without typing its full
pathname.
Unlike normal links, symbolic links can cross filesystems
and link to directories.
See also
link.
symbolic mode --
A method of changing file
permissions
using keyletters to specify which set of permissions to
change and how to change them. For example, to add group
write permission on a file called report using
symbolic mode, you could type chmod g+w report.
Note that you must be the owner of a file or root
to change permissions on that file. You can also change
permissions using
absolute mode.
symbolic window --
A rectangular representation of a window shown on the map
to indicate the position of the window in your workspace.
symbol table --
(programming) Information in an object file about the names of data
and functions in that file; the symbol table and address relocation
information are used by the link editor to compile object files
and by debuggers.
symmetric active mode --
The mode in which a host has configured itself to poll a
time server
that it might synchronize with. In this mode, the host
also allows itself to be polled by that time server.
symmetric multiprocessing --
A multiprocessor system is symmetric when any processor can
perform any function. This ensures even load distribution
because no processor depends on another. Each process is
executed by a single processor.
symmetric passive mode --
The mode in which a time server is polled by a host that
has configured itself in
symmetric active mode.
In this mode, the time server can also poll that host.
synchronization subnet --
A collection of hosts that synchronize time with each
other.
The top layer of the subnet consists of stratum 1 servers.
synchronize clocks --
To set two clocks to the same time and ensure that they are
running at the same speed. The speed at which a
clock
runs is determined by its frequency, that is, how often it
ticks to the next fraction of a second. The design of a
particular clock determines how small that fraction is.
synchronize with a host --
To synchronize the local clock with another host's clock,
either by stepping or slewing the local clock to the time
reported in the NTP packet received from the most
recent poll of that host.
See also
step
and
skew.
syntax --
(programming)
1. Command syntax is the order in which commands and their
arguments must be put together.
The command always comes first.
The order of arguments varies from command to command.
2. Language syntax is the set of rules that describes how the elements
of a programming language can legally be used.
syscall event --
(programming)
When using the GUI debugger, a syscall event suspends
the process and performs the associated commands whenever the process enters
or exits the specified system calls.
Multiple events can be created for the same system call.
system administrator --
The person who looks after the day-to-day running of the
computer and performs tasks such as setting up
user accounts
and making system backups.
system calls --
1. The set of system primitive functions
through which all system operations
are allocated, initiated, monitored,
manipulated, and terminated.
2. The system primitives invoked by user
processes for system-dependent functions,
such as I/O, process creation, and so on.
system console --
The directly connected terminal used
for communication between the operator and the computer.
See also
console terminal.
system initialization --
(programming)
The routines from the driver code
and the information from the master file
that initialize the system (including device drivers).
system name --
An up-to-eight character name for the system;
set in the SYS parameter.
system state --
One of five configurations of the operating system
for which a predetermined set of processes can be executed.
The operating system is running in one of these
states at any given time.
(Also known as
run level
and ``init state''.)