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researchv10 Dan Cross

.SP .5i
.TL
INTRODUCTION
.SP 2
.LP
This volume describes facilities of the version of the
.SM UNIX
operating system that is used
at the system's original home, the
computing science research center of AT&T Bell Laboratories.
Volume 2 discusses certain aspects of the system in more detail.
For tutorial information, consult a standard reference such as
.I "The Unix Programming Environment
by Kernighan and Pike.
.LP
Within the area it surveys, this volume attempts
to be timely, complete and concise.
Where the latter two objectives conflict,
the obvious is often left unsaid in favor of brevity.
It is intended that each program be described
as it is, not as it should be.
Inevitably, as snapshots of a living system, some of
the descriptions may soon go out of date.
When that happens, users may find the latest word in
an on-line form of this book.
.LP
The volume is divided into sections;
each section consists of a number of independent pages.
(Some `pages' spill over beyond one sheet of paper.)
The name of a page is in its upper corners 
together with the section number.
Sections 3 and 9 have further substructure as described in
their respective introductions.
Pages are arranged alphabetically within sections.
Here and in much other documentation,
the notation
.I man (1)
refers to the page for the
.I man
command in section 1.
(This particular command prints selections from the on-line manual.)
.LP
There are nine printed sections and one unprinted appendix.
.DS
1.	Commands
2.	System calls
3.	Subroutines
4.	Devices, line disciplines, and file systems
5.	File formats and conventions
6.	Language conventions
7.	Information sources
8.	Maintenance commands and procedures
9.	Teletype 5620-related software
A.	Other facilities
.DE
Section 1 describes
programs intended to be invoked directly by
the user, in contradistinction to subroutines, which are
intended to be called by the user's programs.
Essential commands generally reside in directory
.CW /bin
(for
.I bin \|ary
programs) or
.CW /usr/bin .
These directories are searched automatically by command interpreters.
.LP
Section 2 describes
entries into the
.UX
kernel
as expressed in C, the primary implementation
language of the system.
.LP
Section 3 discusses
an assortment
of subroutines, mostly for use with C.
The primary libraries in which they are kept are described in
.I intro (3).
Fortran users should consult the
.I port (3)
mathematical library.
.LP
Section 4 discusses `files'
that actually refer to I/O devices,
processing modules that modify the behavior
of some devices,
and `file systems'
that aren't just files on a disk.
.LP
Section 5 gives the structure of particular
kinds of files, for example, the form of the output of the loader and
assembler.
Files internal to only one command
are excluded,
for example compiler intermediate files.
.LP
Section 6 lists 
macro packages, fonts, mail addressing conventions, etc.
.LP
Section 7 is a miscellaneous collection of information sources:
library orders, news, astronomy, geography, calendar, etc.
.LP
Section 8 discusses commands and procedures not intended
for use by the ordinary user.
Most of the commands and files described here
are kept in directory
.CW /etc.
.LP
Section 9 describes software intended for use with the Teletype
5620 terminal.
In this category fall utilities that exploit the terminal and
tools for writing code to run with or on it.
.LP
Appendix A contains information about obsolescent or 
specialized programs.
It is not printed, but is accessible on line through
.I man (1).
.LP
Not all facilities are available across all computers.
Pages for programs with limited distribution
are marked at the top
with the name of at least one computer 
at the home site where
they are known to reside.
.LP
All pages are based on a common format,
not all parts of which necessarily appear.
.RS
.LP
The
.I NAME
subsection lists the exact names of the commands and subroutines
covered
and
a very short description of their purpose.
.LP
The
.I SYNOPSIS
subsection summarizes the use of the
program being described.
.LP
The
.I DESCRIPTION
subsection discusses in detail the subject at hand.
.LP
The
.I EXAMPLES
subsection illustrates interesting usage.
.LP
The
.I FILES
subsection gives the names of files which are
built into the program.
.LP
The
.I
SEE ALSO
.R
subsection gives pointers to related information.
.LP
The
.I DIAGNOSTICS
subsection discusses
the diagnostic indications which may be produced.
Messages which are intended to be self-explanatory
are not listed.
.LP
The
.I BUGS
subsection gives
known bugs and sometimes deficiencies.
Occasionally also the suggested fix is
described.
.br
.RE
.LP
The following conventions are used, particularly in 
section 1:
.RS
.LP
.CW "Program font"
shows literals, file names, and examples.
.LP
.I Italics
designate parameters or arguments.
In descriptions italics also name programs, as a sign that the
programs can be found described in this manual, and as a reminder
that the name is probably a shorthand, 
not a real file name.
.LP
Square brackets [ ] around an argument
indicate that the argument is optional.
.LP
Ellipses `.\|.\|.' indicate that the previous item
may be repeated.
.LP
A final convention is used by the commands themselves.
An argument beginning with a minus sign 
.CW -
usually means a command option
even if it appears in a position where a file name
could appear.
Therefore, it is unwise to have files
whose names begin with 
.CW - .
.br
.RE
.LP
Following this introduction are a classified table of contents,
a permuted index, and a glossary.
.SH
HOW TO GET STARTED
.LP
This section sketches the basic information
you need to get started on
.UX :
how to log in and log out,
how to communicate through your terminal,
and how to run a program.
See Kernighan and Pike for a more complete introduction.
.LP
.I
Logging in.\ \ 
.R
You must call
.UX
from an appropriate terminal.
Most any \s8ASCII\s0 terminal capable of full duplex operation and generating
the entire character set can be used.
You must also have a valid user name,
which may be obtained, together with necessary telephone numbers
or computer names,
from the system administrator.
After a data connection is established,
the login procedure depends on what kind of terminal
you are using.
.LP
.I
.I
Dial-up terminals:\ \ 
.R
If there is a half/full-duplex switch, set it at full-duplex.
When you have established a data connection,
the system types out a few characters, intended to be
.CW login: .
If they appear as gibberish, the computer is sending at the wrong 
baud rate.
Depress the `break'
key;
this is a signal
that a different speed terminal
is in use.
The system will type
.CW login:
at another
speed.
Continue depressing the break key
until
.CW login:
appears, then respond with your user name.
End each line you type with a carriage return.
.LP
.I
Hard-wired terminals.\ \ 
.R
Hard-wired terminals usually begin at the right
speed, up to 19200 baud; otherwise the preceding instructions
apply.
.LP
.I
Datakit\(rg terminals.\ \ 
.R
Make sure that any on-line/off-line switch is turned to on-line.
If the terminal types gibberish, depress the `break' key repeatedly
until you see the prompt
.CW "Number please:"
or
.CW "Destination please:"  .
Respond with the name of the computer you wish to connect to, 
followed by a carriage return.
When the computer prompts
.CW login:
proceed as above.
.LP
For all terminals, it is important
that you type your name in lower case if possible.
If you type
upper-case letters, the system
will assume that your terminal cannot generate lower-case
letters and will translate all subsequent upper-case
letters to lower case.
.LP
Upon logging in you may be presented with a `message of
the day'.
You may also be notified of incoming mail.
The final evidence that you have successfully
logged in is that a shell program
will type a prompt (normally 
.CW $  )
to you.
(The shell is described below under
`How to run a program.')
.LP
Terminals come with a bewildering variety of capabilities,
which the system may have to be aware of.
Get somebody who knows to help customize a 
.CW \&.profile
description of your terminal to set things properly
upon logging in.
For more information, consult
.I sh (1)
about profiles,
.I environ (5)
about environments, and
.I tabs (1),
.I stty (1),
.I tty (4),
and
.I ttyld (4)
about terminal settings.
.LP
.I
Logging out.\ \ 
.R
There are two ways to log out:
.IP
Type an end-of-file indication
(EOT character, 
control-\f(CWd\fP)
to the shell.
The shell will terminate and a
.CW login:
or
.CW "Number please:"
message
will appear again.
.IP
Simply hang up or turn your terminal off.
.LP
.I
How to communicate through your terminal.\ \ 
.R
When you type characters, a gnome deep in the system
gathers your characters and saves them in a secret
place.
The
characters will not be given to a program
until you type a return.
.LP
.UX
terminal I/O is full-duplex.
It has full read-ahead, which means that you can
type at any time,
even while a program is
typing at you.
If you type while the computer is printing,
the input may appear interleaved with the output.
However, whatever you type will be saved
up and interpreted in correct sequence.
.LP
In typed input, the character
.CW @
kills all the preceding characters in the line, so
typing mistakes
can be repaired.
A backspace
erases the last character typed.
Successive backspaces
erase characters back to, but
not beyond, the beginning of the line.
.CW @
and backspace can be transmitted to a program
by preceding them with
.CW \e .
(So, to erase
.CW \e ,
you need two backspaces.)
.LP
The `delete' or `rubout' key causes an
.I
interrupt signal,
.R
as does the
`break' key.
This signal
generally causes whatever program
you are running to terminate.
It is typically used to stop a long printout that
you don't want (with varying degrees of promptness).
However, programs can arrange either to ignore
this signal altogether,
or to be notified, instead of being killed, when it happens.
The editor,
.I ed (1),
for example, catches interrupts and
stops what it is doing,
instead of terminating, so that an interrupt can
be used to halt an editor printout without
losing the file being edited.
.LP
It is also possible to suspend output temporarily by typing
control-\f(CWs\fP
and later resume output with 
control-\f(CWq\fP.
.LP
The
.I quit ""
signal is generated
by typing 
control-\f(CW\e\fP
or
control-\f(CW|\fP.
It not only causes a running program to terminate
but also generates a file with the core image
of the terminated process.
Quit is useful
for debugging.
.LP
.I
How to run a program; the shell.\ \ 
.R
When you have successfully logged in, a program
called the shell is listening to your terminal.
The shell reads typed-in lines, splits them up
into a command name and arguments, and executes the command.
A command is simply an executable program, which the
shell finds by looking in several standard places.
You can 
place commands in your own directory and have the shell find them there.
There is nothing special about system-provided
commands except where they live.
.LP
The command name is always the first word on an input line;
it and its arguments are separated from one another by
spaces.
.LP
When a program terminates, the shell will ordinarily regain control and type 
a prompt at you to indicate that it is ready for another command.
.LP
The shell (and the underlying system) has a distinctive
ability to combine programs by piping the output of one into the
input of another.
In general, programs have been designed to be usable in pipelines
as well as on their own.
The shell has many other capabilities, which are described in detail in
.I sh (1).
.LP
.I
Bitmap terminals.\ \ 
.R
To get the most out of the Tenth Edition system, you will probably
wish to use a Teletype 5620 or 630 terminal, run with
.I mux (9.1).
This provides
mouse control, graphics, and multiple layers, each of which acts like
a separate, simultaneously running
.UX
terminal, complete with its own shell.
Text in a
.I mux
layer can be edited on screen.
The editor
.I sam (9.1)
and the typesetter simulator
.I proof (9.1)
are particularly useful programs that run only under
.I mux.
.LP
.I
The current directory.\ \ 
.R
.UX
has a file system arranged in a hierarchy of directories.
When you were given a user name by a system administrator,
you were also given a home directory (ordinarily
with the same name as your user name).
When you log in, any file
name you type is by default
in this directory.
Since you are the owner of this directory, you have
full permission to read, write, alter, or destroy
its contents.
Permissions to have your will with other directories
and files will have been granted or denied to you
by their owners.
As a matter of observed fact, few users
protect their files from perusal by other users.
.LP
You need not do all your work in the home directory.
To switch to another directory use the change directory
command
.I cd,
described in
.I sh (1).
.LP
.I
Path names.\ \ 
.R
To refer to files not in the current directory, you must
use a path name.
Full path names begin with
.CW / ,
the name of the `root' of the
whole file system.
After the slash comes the name of a subdirectory, another slash
and a sub-subdirectory, and so on
until finally a
file name is reached.
For example,
.CW /usr/lem/filex
refers to the file
.CW filex
in the directory
.CW lem ;
.CW lem
is itself a subdirectory of
.CW usr ;
.CW usr
.R
springs directly from the root.
.LP
If your current directory has subdirectories,
the path names of files therein begin with
the name of the subdirectory with no initial 
.CW / .
.LP
A path name may be used anywhere a file name is
required.
.LP
Important commands which modify the contents of files
are
.I cp (1),
.I mv 
(described in
.I cp (1)),
and
.I rm (1),
which respectively copy, move (i.e. rename) and remove files.
To find out the status of files or directories, use 
.I ls (1).
See
.I mkdir (1)
for making directories.
.LP
For a fuller discussion of the file system, see
Kernighan and Pike.
It may also be useful to glance through
section 2 of this manual, which discusses
system calls, even if you don't intend
to deal with the system at that level.
.LP
.I
Environment.\ \ 
.R
Many things can be changed in the environment:
the already-mentioned erase
character, properties of your terminal, directories from which
you wish to execute commands, news notification, etc.
Your
.CW \&.profile
file can make these settings automatically upon login.
.LP
.I
Writing a program.\ \ 
.R
The principal language processors are
.I cc (1)
for C,
.I f77 (1)
for Fortran, and
.I awk (1).
Processors for Basic, Pascal, Snobol, Lisp, Macsyma, ML, and others are available.
For compile-before-run languages
enter the text of a source program into a
file, using one of the editors,
.I ed (1),
.I sam (9.1),
or
.I vi (1).
By convention C programs are stored in files with names
ending in
.CW .c ,
Fortran programs in 
.CW .f .
After the program text has been entered through 
the editor
and written on a file, you can give the file
to the appropriate language processor as an argument.
The output of a compiler
will be left in a file named
.CW a.out
in the current directory.
(If the output is precious, use
.I mv
to move it to a less
exposed name soon.)
.LP
When you have finally gone through this entire process
without provoking any diagnostics, the resulting program
can be run by giving its name (\c
.CW a.out
if you've not arranged otherwise)
to the shell
in response to the shell prompt.
.LP
Your programs can receive arguments from the command line
just as system programs do,
see
.I exec (2).
.LP
.I
Text processing.\ \ 
.R
Almost all text is entered through the editors.
The commands most often used to display text are
.I cat (1),
.I pr (1),
and
.I troff (1).
.LP
The
.I cat
command simply dumps text
on the terminal, with no processing at all.
The
.I pr ""
command paginates the text, supplies headings,
and has a facility for multi-column output.
.LP
.I Troff
prepares documents for a
phototypesetter.
Used naked, it requires careful forethought, but for
ordinary documents it has been tamed; see
.I ms (7).
It was used to produce this manual.
Its output can drive various devices including
laser printers and graphic terminals; see
.I lp (1)
and
.I proof (9).
.LP
.I
Status inquiries.\ \ 
.R
.I Who (1)
prints a list of users presently logged in.
.I Date (1)
prints the current time and date.
.I Pwd (1)
tells what directory you're working in;
.I where ,
described on the same page,
tells what machine you're on.
.I Ls (1)
will list the files in your directory or give
status information about particular files.
.LP
.I
Surprises.\ \ 
.R
Certain commands provide inter-user communication.
Even if you do not plan to use them, it would be
well to learn something about them, because someone else may
aim them at you.
.LP
To communicate with another user currently logged in,
.I write (1)
may be used, but
.I mail (1)
is both more polite and more reliable.
.I Mail
leaves a message that will be announced
to another user at next login, if not sooner.
.I Vismon (9.1)
and
.I sh (1)
provide ways to monitor incoming mail continuously.
.LP
.I
Multiple machines.\ \ 
.R
Tenth Edition systems have tentacles to many other 
machines.
The file systems of other
.UX
systems may be accessible through
directory 
.CW /n .
Thus you may change current directory to one of these machines, although
computing on your behalf is still being done on the machine you
logged into.
You may transmit data among such machines just as within one machine by using
.I cp (1)
or I/O redirection in the shell.
You may also log into a remote machine to do processing there with
input and output passing through the
local machine; see
.I con (1).
.LP
Datakit connections exist throughout Bell Laboratories.
File transmission, over Datakit and over dialup lines to
even more remote machines, is provided by
.I uucp (1).
Mail extends all over the world.
See
.I mail (6)
for how to send mail to destinations on networks such
as the ARPA Internet, Bitnet, or ACSnet (in Australia.)

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