Using System Resources
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Copyright CourseWare Technologies Inc., 1985-88
Lesson - 6
USING SYSTEM RESOURCES
MENU
Using System Resources|Topics to Learn|6-0|8,50
# Topic
--- -------
1 - Introduction to System Resources
2 - How to Print Files
3 - Using Magnetic Disks
4 - Using Magnetic Tape
5 - The UNIX Mail System
0 - Return to Main Menu
TOPIC1
Introduction to System Resources
P1
Using System Resources|Introduction to System Resources|6-1.1|14,54
As you recall, the integral components of your
computer system are the central processing unit (CPU),
the primary memory, the disks drives, and the terminals.
Besides the integral components, your UNIX
system is probably equipped with several other
peripheral devices including:
* an off-line printer,
* one or two floppy disk drives,
* a magnetic and/or cartridge tape drive, or
* an optical disk, etc.
P2
Using System Resources|Introduction to System Resources|6-1.2|10,54
The peripheral devices permit you to obtain
a printed copy of your text or store data on
removable media such as disks or tapes, thus
providing you with a means for moving data from
one computer system to another.
Each of your peripheral devices is treated
like a file by the system and, therefore, has a
device file name.
P3
Using System Resources|Introduction to System Resources|6-1.3|15,54
This lesson will show you commands for using
your system's off-line printer, commands for reading
and writing to disks, and commands for using other
devices.
Because the peripheral manipulation commands
use some advanced concepts, you are asked to accept
the commands at this point without much discussion
of how they work.
The latter chapters and other tutorials will
provide you with the background necessary to fully
understand them.
TOPIC2
How to Print Files
P4
Using System Resources|How to Print Files|6-2.1|13,54
The standard UNIX command for sending files
to an off-line printer is lpr. To print a file
named report the command would be:
lpr report
The lpr command has several options including
an option to request multiple copies of the same
file. For example, to print five (5) copies of the
file report you would type:
lpr -n5 report
Using System Resources|How to Print Files|6-2.1|13,54
The standard UNIX command for sending files
to an off-line printer is lp. To print a file
named report the command would be:
lp report
The lp command has several options including
an option to request multiple copies of the same
file. For example, to print five (5) copies of the
file report you would type:
lp -n5 report
TOPIC3
Using Magnetic Disks
P5
Using System Resources|Using Magnetic Disks|6-3.1|10,54
If your UNIX system can handle tens or hundreds
of users simultaneously, then the chance for you to
have access to a floppy disk drive on that system is
very slim.
If, on the other hand, you are using a UNIX
workstation or a supermicro based system, then floppy
disks are probably the most common removable data
storage medium.
P6
Using System Resources|Using Magnetic Disks|6-3.2|8,54
Before using a floppy disk you must know the
required capacity of the disks used on your system.
Capacity is measured in bytes. A byte is the
amount of space needed to store one character. A
kilobyte (Kbyte) is 1024 bytes. A megabyte (Mbyte)
is over one million bytes (1,024,000).
P7
Using System Resources|Using Magnetic Disks|6-3.3|7,54
The most common type of disk media is double
sided double density, which permits you to store
between 360 and 800 Kbytes of data depending on the
system you are using.
The double sided high density drive supplied
with your UNIX system uses high density media which
permit you to store 1.2 Mbytes of data.
P8
Using System Resources|Using Magnetic Disks|6-3.4|9,54
All magnetic media must be formatted before it can
be used.
The command to format a floppy disk varies between
systems, however the direct command is always some
version of format. For example:
fmtflop $Unixdev$
format $Xenixdev$
P9
Using System Resources|Using Magnetic Disks|6-3.5|7,54
Check with your system administrator before using
these commands to make sure you are not formatting the
the system hard disk by mistake!
You must also be aware that formatting will
destroy any data already on the disk.
P10
Using System Resources|Using Magnetic Disks|6-3.6|10,50
It is important to save or backup your files
on some removable medium (usually floppy disks)
on a regular basis. If you don't and the system
crashes, you can lose all of your work. Backing
up is also called dumping or archiving files.
Once a disk is formatted you can archive (or
write) files onto it using either the tar or cpio
command.
P11
Using System Resources|Using Magnetic Disks|6-3.7|4,40
The tar (tape archiver) command and
the cpio (copy files in and out) command
are similar. They copy files on or off
of a tape.
P12
Using System Resources|Using Magnetic Disks|6-3.8|16,57
cpio reads the standard input to obtain a list
of pathnames and copies those files onto the standard
output together with the pathname and status information.
The format of the cpio command is:
ls pathname(s) -print | cpio -ocBv > specialfile
pathname is the pathname of every file to be
copied;
specialfile is the name of the file corresponding to
a disk drive;
B means to Block 5120 bytes per record;
c means to create ASCII header information;
v indicates to verbosely list the filenames.
Using System Resources|Using Magnetic Disks|6-3.8|14,50
The tar command is one of the most reliable
commands for data storage, portability and recovery.
It was originally designed to operate on magnetic
tapes; however it also permits one to copy files to
or from other magnetic disks.
The format of the tar command for archiving is:
tar cvf specialfile files
where f expects specialfile to be the name of the file
corresponding to a disk drive, c creates a new archive,
and v is for verbose.
P13
Using System Resources|Using Magnetic Disks|6-3.9|9,54
Before archiving on a floppy disk, make sure
that the disk is firmly in place in the floppy disk
drive and that the latch on the door is closed.
The command to archive the file report onto the
ls report | cpio -ocBv > $Unixdev$
tar cvbf 20 $Xenixdev$ report
P14
Using System Resources|Using Magnetic Disks|6-3.10|9,54
You may obtain the table of contents of the
files on your disk either by using a selection from
your system's menu or by using a direct command.
The command that allows you to check the
table of contents on an archive made with cpio is:
cpio -icBtv < $Unixdev$
The command to see which files are stored on
the disk is:
tar tvbf 20 $Xenixdev$
P15
Using System Resources|Using Magnetic Disks|6-3.11|13,54
You can restore files saved on a disk, that
is, copy files from the floppy disk back onto the
hard disk.
Before copying files from the floppy disk onto
the hard disk, make sure that the files being copied
from the floppy disk will not overwrite any files
with identical names on the hard disk!
You may restore one or several files from a
floppy disk.
P16
Using System Resources|Using Magnetic Disks|6-3.12|11,54
The command to restore the files lesson and
accept.c into the current directory from the floppy
disk is:
tar xvbf 20 $Xenixdev$ lesson accept.c
The command to restore all of the files on the
disk is:
tar xvbf 20 $Xenixdev$
Using System Resources|Using Magnetic Disks|6-3.12|13,54
The command to restore all of the files on the
disk is:
cpio -i [Bcdmrtuv] < device name
For example: cpio -icBdv < $Unixdev$
The command to restore the files lesson and
accept.c into the current directory from the floppy
disk is:
cpio -icdBv < $Unixdev$ lesson accept.c
TOPIC4
Using Magnetic Tape
P17
Using System Resources|Using Magnetic Tape|6-4.1|14,54
The commands for reading and writing to magnetic
tape are similar to those for floppy disks. The
difference is the name of the device file associated
with the magnetic tape drive.
If your system has the tar utility and a magnetic
tape drive, then your magnetic tape drive is the default
archiving device for tar. For example, to archive all
the files in the current directory and in all the
directories below it onto the default archiving device,
mount a blank tape and type:
tar c
P18
Using System Resources|Using Magnetic Tape|6-4.2|6,54
In Topic 3, Using Magnetic Disks, you saw a few
examples using the cpio command to copy files on and
off of magnetic disks. This command can also be used
to copy files to and from magnetic tapes; only the name
of the device will change from that of the disk drive
to that of the tape drive.
P19
Using System Resources|Using Magnetic Tape|6-4.3|6,54
If you are using a Hewlett-Packard computer, you
can optimize the data transfer rate between some data
cartridge units and your computer, and reduce wear
and tear on your data cartridges and drives by using
the tcio command in conjunction with the cpio
command.
P20
Using System Resources|Using Magnetic Tape|6-4.3|16,54
The syntax of the tcio command is:
tcio [-ir] -l # -n # tape drive name | cpio ...
where
-i stands for copy in
-r unloads the tape from the tape drive
-l # for multi-cartridge drives, starts by loading
cartridge number #
-n # for multi-cartridge drives, specifies the maximum
number (#) of cartridges to be used in a multi-tape
transfer
The command will read the Command Set 80 Cartridge Tape Unit
and write the data to the standard output which then sends
it to cpio.
TOPIC5
The UNIX Mail System
P18
Using System Resources|The UNIX Mail System|6-5.1|12,54
Your UNIX system provides you with the
capability of sending electronic mail to other users
on your system.
You may be able to send electronic mail to the
users on another UNIX system as well; see your system
administrator for details.
Here, we'll show you how to send mail to the
local users.
P19
Using System Resources|The UNIX Mail System|6-5.2|14,54
The command to send mail is mail.
To send a mail message to the user joan
the command would be:
mail joan <CR>
The system will prompt you with: Subject:
To which you should type in a subject followed by <CR>
On the next line you can type your message. Terminate
your message with <CONTROL-d> and you should get your
shell prompt back.
P20
Using System Resources|The UNIX Mail System|6-5.3|15,54
If you have a mail message, after you log in you
will be prompted with:
You have mail
To read your mail you type:
mail <CR>
You will get a note specifying the sender, the date and
the subject.
By typing <CR> you can read mail messages in the order
they were received.
MAIL