ITCwiki - User contributions [en]

Introduction to DOS

2013-05-13T01:05:07Z

JBackley:

'''DOS''', short for "Disk Operating System", is a family of similarly designed computer operating systems originally popularized by Microsoft in the early 1980s which remained in popular use through about the year 2000 as the technology underlying some versions of the Windows graphical user interface. From nearly the beginning there were competing versions of DOS available, the most popular being MS-DOS (by Microsoft) and IBM PC DOS (also originally by Microsoft). Other versions of DOS include DR-DOS, FreeDOS, PTS-DOS, ROM-DOS, JM-OS, and several others. The most popular version of DOS still under active development and maintenance is FreeDOS, an open source, MS-DOS compatible version of DOS. Despite the variety of DOS vendors the systems are generally compatible in that a program written on one version of DOS (usually MS-DOS) will usually run on any other vendor's version. One notable exception to this rule is ProDOS written for Apple II based computers which was incompatible because of underlying differences in the hardware, such as the CPU architecture.

Although DOS has largely fallen out of favor as a mainstream operating system in favor of Windows NT based operating systems it remains a useful tool for any PC technician and at least a basic understanding of DOS is still useful. In addition Windows NT based operating systems still retain a "command line interface" (CLI) which uses familiar DOS commands and conventions to accomplish many system maintenance and repair functions.

== History ==
Early hobbyist personal computers of the late 1970s and early 1980s ran a variety of, often incompatible, operating systems. One of the most popular at the time IBM was developing their original PC was the CP/M operating system by Digital Research which, at the time, ran on the 8-bit Intel 8080 and Zilog Z80 processors. During the development of the IBM PC an operating systems was needed for the Intel 8088 processor around which the system was based. IBM initially approached then Microsoft CEO Bill Gates about developing an 8088 version of CP/M but was directed to Digital Reseach, the owner of CP/M.

For obvious cost reasons IBM was looking for a blanket license to relabel and sell CP/M as IBM PC-DOS with their new computer. Digital Research founder and owner Gary Kildall refused, holding out for a royalty based deal at which time IBM withdrew their offer and returned to Microsoft looking for an alternative operating system. This time Gates approached Seattle Computer Products about a new CP/M like operating system code named "QDOS" which stood for "Quick and Dirty Operating System" developed by Tim Paterson to test Intel 8086 hardware made by Seattle Computer Products. Gates was able to secure a nonexclusive license to QDOS in December of 1980 for $25,000 and soon after hired designer Tim Paterson to port the operating system to the IBM PC which used the less expensive Intel 8088 CPU.

Shortly before the launch of the IBM PC, in the summer of 1981, Microsoft purchased all rights for QDOS (now known as the commercial product 86-DOS) from Seattle Computer Products for $50,000. Microsoft, in-turn, licensed the IBM PC version of 86-DOS to IBM to be sold as IBM PC DOS 1.0. In a stroke of genius the license agreement between Microsoft and IBM was non-exclusive, allowing Microsoft to license the operating system to other PC manufacturers when they arrived some time later.

The original DOS was designed to look and act much like the competing CP/M operating system, and was even compatible with CP/M programs to some extent, but was much less expensive and soon overtook CP/M as the primary operating system of the personal computer.

== Storage Structure ==
DOS uses a ''drive'' and ''directory'' based file storage system. One of the easiest ways to envision this storage system is to think of drives as file drawers in an office and directories as file folders in those drawers. Directories can be ''nested'', that is put inside of each other, creating a sort of family tree style storage system. The main directory on each drive is called the ''root directory'' or ''root'' and is identified in DOS by a single backslash ''\''. This directory can contain both files and other directories, referred to as ''sub-directories''.

Each disk drive in the system is identified by a ''drive letter''. By DOS convention the primary floppy disk drive is identified as ''A'' and the secondary as ''B'' ''Fixed disks'' (more commonly referred to today as ''hard disks'' or ''hard drives'' are identified by drive letters starting with ''C''.

DOS uses the ''file allocation table'' (''FAT'') ''filesystem'' or the newer ''FAT32'' filesystem for storing data on disks. Each file stored in this filesystem has a ''filename'' of eight characters or less without spaces (though FAT32 allows for longer filenames and spaces) and a ''file extension'' of three characters which identifies the type of file. Because some characters are used by DOS for other purposes such as identifying drives, directories, file extensions, etc. they cannot be used in filenames. The list of invalid characters includes:

. " / \ [ ] : * | < > + = ; , ?

You can pick almost any three character file extension when naming a file except three which are reserved for programs which run on your computer: <code>COM</code>, <code>EXE</code> and <code>BAT</code>. Although there are many possible file extensions there are some which are frequently encountered and are useful to know:

{| class="wikitable"
! Extension || File Type
|-
| <code>BAK</code> || A backup copy of a data file
|-
| <code>BAT</code> || A batch script program file
|-
| <code>COM</code> || A command program file
|-
| <code>DOC</code> || A word processor document file
|-
| <code>EXE</code> || An executable program file
|-
| <code>SYS</code> || A system file
|-
| <code>TXT</code> || A text file
|}

== The DOS Prompt and Running Programs ==
The ''DOS prompt'', sometimes referred to more generically as a ''command prompt'', is the main method of interaction with DOS. It is used to execute programs, change drives, change directories, move files, list directory contents and just about everything else. The default prompt shows the currently active drive followed by a greater than sign looking something like this:

C>

One of the simplest, and most frequently done things from the command prompt is executing a program. As mentioned earlier programs which run on your computer end with one of three file extensions: <code>COM</code>, <code>EXE</code> or <code>BAT</code>. If you are in the directory containing the program all you need to do is enter the program's filename at the prompt and press the Enter or Return key. Programs can be run without entering the extension on the filename, DOS will automatically try to run the program you entered regardless of whether you have entered a file extension. For example, if you are in a directory which contains the Microsoft Word program you could run it by entering the command:

C> MSWORD

and pressing the Enter or Return key. This would ''execute'', or run, the <code>MSWORD.EXE</code> program.

== Navigating Drives and Directories ==
=== Changing Drives ===
DOS can only operate in one directory on one drive at a time so the ability to change the drive and ''working directory'' is important. To move from one drive to another simply enter the drive letter you wish to switch to, followed by a colon, at the prompt and press Enter or Return:

C> A:

This would switch from the C drive to the A drive. The basic prompt would also change to show the drive change. To switch back to the C drive simply enter:

A> C:

Note that you are only able to change to drives which exist and floppy drives which contain a floppy disk. Attempting to change to a drive which does not exist or an empty floppy drive will result in an error.

=== Changing Directories ===
Let's assume that we have a basic system with a root directory and a subdirectory which contains two more subdirectories:

{| class="wikitable"
! Location || Description
|-
| <code>\</code> || The root directory
|-
| <code>\DOCS</code> || The DOCS directory under the root
|-
| <code>\DOCS\WORK</code> || The WORK directory under the DOCS directory under the root
|-
| <code>\DOCS\HOME</code> || The HOME directory under the DOCS directory under the root
|}

To move from one directory to another we need to use the change directory command '''CD'''. Assuming that we are in the root directory of the C drive and wished to change to the <code>DOCS</code> directory we could enter the command:

C> CD DOCS

and press the Enter or Return key. This would change the working directory from the root (''\'') to DOCS (''\DOCS''). If we then wanted to enter the HOME directory (''\DOCS\HOME'') we would enter:

C> CD HOME

To return to the root directory of the current drive enter:

C> CD \

It is also possible to change directories by entering the complete ''path'' to the directory. In this way you are able to quickly move from one location to another on the drive. To move directly from the root to the WORK directory enter:

C> CD \DOCS\WORK

You can also use a special directory command to move back up one level at a time. If you are in the <code>\DOCS\WORK</code> directory and want to move up one level to <code>\DOCS</code> you can use the special "'''..'''" directory which means, effectively, one directory up.

C> CD ..

=== Changing the Prompt ===
With all this moving around from one directory to another it can be difficult to remember the working directory (the directory you're currently in). Luckily, the default prompt which shows the drive you're working on can be changed to also show the working directory. This is done using the '''PROMPT''' command. One of the most useful prompts is simply displaying the current drive and directory path. This is done by entering the command:

C> PROMPT $p$g

This will change the prompt to something like:

C:\>

which shows that you are in the root directory of the C drive, in the DOCS directory this would look like:

C:\DOCS>

Clearly, this is more useful than the standard prompt but to return to the standard prompt just enter the PROMPT command without any options:

C:\> PROMPT

which will return you to the basic prompt. The prompt command can be used with many other options to, for example, display the date and time along with the working directory but such long prompts are usually avoided because of the limited amount of area on the monitor.

=== Viewing Directory Contents ===
Another useful tool is the '''DIR''' command which allows you to list the contents of a directory, including both files and subdirectories, on the screen. To display a list of files and directories in the current working directory enter the '''DIR''' command:

C:\> DIR

Sometimes the list of files is so long that the beginning of the list scrolls off the top of the screen before you can read the filenames. To prevent this you can add the <code>/P</code> option to the command:

C:\> DIR /P

This will cause the system to pause after each screen and ask you to press a key to see the next screen of files. While the basic DIR command will provide you with the filenames as well as sizes, dates and times the file was created or modified it is possible to see more files on each screen by using the <code>/W</code> option:

C:\> DIR /W

The <code>/W</code> option means use a wide display, giving only the filenames. It is also possible to list the files in another directory or on another drive without switching to that drive:

C:\> DIR A:

Here the files from the root directory of the A drive will be listed without changing the working directory. The various options can also be combined:

C:\> DIR /W/P

will display files in a wide listing as well as pause between each screen of filenames.

===Moving and Deleting files===
To move the contents of folder A to folder B you would use the move command:

C:\>Move C:\A\*.* C:\B\

With the Move command you can use the /Y switch to say yes to any messages about over writing files.

To delete the contents of folder A you would use the del command:

C:\>Del C:\A\*.*

To override messages about deleting read only files use the /F switch.

To delete a specific file you have use the same del command without the asterisks:

C:\>Del C:\A\OldFile.txt

===Networking===
To view the current network settings use the ipconfig command:

C:\>ipconfig

To view a detailed version of the current networks settings use the /all switch

C:\>ipconfig /all

To flush the DNS records from the computers cache use the /flushdns:

C:\>ipconfig /flushdns

To reregister all DNS names and to renew the DHCP lease you can use /registerdns switch:

C:\>ipconfig /registerdns

To set the IPv4 address of your Local Area Connection you must use the netsh command:

C:\>netsh interface ip set address name="Local Area Connection" static 192.168.1.2 255.255.255.0 192.168.1.1

You can also use netsh to set the Local Area Connection to use DHCP:

C:\>netsh interface ip set address "Local Area Connection" dhcp

To specify a different DNS server you can use the set dns part of netsh:

C:\>netsh interface ip set dns "Local Area Connection" static 192.168.1.1

===Shutting down the computer===
To shutdown the PC you can use the shutdown command:

C:\>Shutdown

To restart the computer you also use the Shutdown command but with the -r switch.

C:\>Shutdown -r

To specify how long to wait to shutdown or restart use the -t switch followed by the number of seconds to wait.

C:\>Shutdown -r -t 60

Sometimes you have applications that need responses before exiting (Outlook). You can use the -f switch to force the applications to close.

C:\>Shutdown -s -t 0 -f

Chapter 5 Study Guide

2012-03-29T23:10:41Z

JBackley: /* Floppies */

==/Dev directoy==
The /dev directory contains the special device files that control access all the devices. Two main types of devices under all systems:

'''Character devices'''

Data transfers character by character to and from the device.

'''Block devices'''

Transfers chunks or blocks of information at a time by using physical memory to buffer the transfer

To view the type of the file use the following command
ls -l/dev/dsk

Major and minor numbers are associated with the device special files in the /dev directory and are used by the operating system to determine the actual driver and device to be accessed by the user-level request for the special device file.

The major number identifies the device class or group, such as a controller for several terminals. The major number is assigned, sequentially, to each device driver by the Installable Driver Tools during driver installation.

The minor number identifies a specific device, such as a single terminal. Minor numbers are assigned to special files by the driver writer in another system configuration file called the Node file.

==Filesystems==
'''Filesystem:'''
The organization imposed on a physical storage medium that is used to manage the storage, store, retrieve, and update data on device. All filesystems have three common components: the superblock, the inode table, and the data blocks. Together they organize files and allow rapid access to and retrieval of data.

Filesystems used by most linux distributions:

Extended Filesystem - ext (Linux)

Second Extended Filesystem - ext2 (Linux)

Third Extended Filesystem - ext3 (Linux, journalling)

Reiser Filesystem - reiserfs (Linux, journalling)

IS0 9660 Filesystem - iso9660 (CD-ROM)

Minix Filesystem - Minix (Minix. first filesystem used by Linux)

FAT 16 bit - msdos (DOS, Windows)

Virtual Fat Fielsystem - vfat (DOS, Windows) Supports long filenames

Network Filesystem - NFS

Uniform Filesystem - ufs ( BSD, Solarius, NeXTStep)

UMSDOS Filesystem - umsdos (Unix filesystem on DOS)

jfs (Linux, journalling)

ntfs - Used by Windows

==Mounting==

'''Mounting''' the process used to associate a device with a directory in the logical directory tree such that users can store data on that devices.

A '''mount point''' is a physical location or a directory in the partition used as a root filesystem.

==Floppies==

Used to transfer small amounts of information from computer to computer in the past
Not available on all systems today
Each disk must be formatted with a filesystem prior to being used to store files
After formatting then you must mount it on the directory tree before it can be used

Use the mkfs (make file system) command to format the floppy disk
Specify the filesystem type with a –t switch
Specify a different file system name after the –t option such as the DOS FAT filesystem:

mkfs –t msdos /dev/fd0

If you don’t specify the filesystem then the default assumed is the ext2 file system: mkfs /dev/fd0

To mount a device on the directory tree use the mount command with options to specify the filesystem type to mount the directory.

For example:
mount -u /media/floppy

To unmount use the following command: unmount /media/floppy

==CDs and DVDs==

Can be mounted with mount and unmounted with umount commands.
Device files used by these drives are different than Floppies

Standard Configurations:
Primary master (dev/had)
Primary slave (dev/hdb)
Secondary master (dev/hdc)
Secondary slave (dev/hdd)

If you have SATA or SCSI drive then Linux uses different names
First SATA/SCSI drive (/dev/sda, /dev/scd0, /dev/sr0, and /devsg0)
Second SATA/SCSI drive ( /dev/sdb, /dev/scd1, /dev/sr1, and /dev/sg1)
Third SATA/SCSI drive ( /dev/sdc, /dev/scd2, /dev/sr2, and /dev/sg2

Symbolic Links
/dev/cdrom- 1st CD-ROM drive
/dev/cdrw 1st CD-RW drive
/dev/dvd 1st DVD-ROM drive
/dev/dvdrw 1st DVD-RW drive

==ISO 9660 File System==
CDs, and DVDs, use this filesystem type.

Are read-only when accessed using a Linux

You must use a disk-burning software to record to a CD, or DVD.

To mount a CD or DVD to a directory use this filesystem type and add the –r (read only) option to the command

For example:
mount –r –t iso9660 /dev/cdrom /media/cd

Not limited to CDs, and DVDs.

You can also create ISOs.

To create an ISO image from a directory of files use the mkisofs command.

For example:
mkisofs –RJ –o newimage.iso/data
mount –o loop –t iso9660 newimage.iso /mnt

==Hard Disks==
3 Flavors of Hard Disks: PATA, SATA, SCSI

'''PATA'''

Primary master (/dev/hda)

Primary slave (/dev/hdb)

Secondary master (/dev/hdc)

Secondary slave (/dev/hdd)

'''SATA/SCSI'''

/dev/sda

/dev/sdb

/dev/sdc

Etc.

Each partition can contain separate filesystems

Can be mounted to different mount point directories

Linux always requires two partitions

One for the root and One for the swap (virtual memory)

Partitions decrease the likely hood of corruption in the file system

Partitions are definitions stored in the first readable sector, known as the Master Boot Record (MBR)

Large drisks > 2TB use a GUID Partition Table (GPT) to allow for additional addressing of the sectors

Hard Disks can only contain up to four primary partitions but you can created extended partitions to overcome this.Extended partitions can then contain many more subpartitions called logical drives.Partitions can be created specific to a certain file system. You can create partitions at installation using the graphical installation program or you can create partitions after the install using the fdisk command.

==fdisk Options==
Some of the more common options for fdisk.

-h, --help
displays a help message.

-v, --version
displays the program’s version.

-L, --linux-fdisk
turns on Linux fdisk compatibility mode. This is the same as running lfdisk.

-G, --gnu-fdisk
turns off Linux fdisk compatibility mode.

-i, --interactive
where necessary, prompts for user intervention.

-p, --script
never prompts for user intervention.

-l, --list
lists the partition table on the specified device and exits. If there is no device specified, lists the partition tables on all detected devices.

-r, --raw-list
displays a hex dump of the partition table of the disk, similar to the way Linux fdisk displays the raw data in the partition table.

-u, --sector-units
use sectors, instead of cylinders for a default unit.

-s, --size=DEVICE
prints the size of the partition on DEVICE is printed on the standard output.

-t, --list-partition-types
displays a list of supported partition types and features.

'''cfdisk''' will give you the GUI based fdisk program.

Reboot to save changes to the MBR or GPT.

After reboot, you can use the mkfs, mount, and unmount commands specifying the partition device file as an argument

Swap partitions must be prepared to swap partitions and activate them for use on Linux.

Use the mkswap command to prepare the swap partition.

Use the swapon command to activate it.

Use '''Logical Volume Manager (LVM)''' to create volumes

Volumes can contain filesystems and mounted to directories within the Linux filesystem hierarchy

More flexible than using partitions

You can use free space from any partitions on any hard disks to create the volume

Additional hard disks can easily be added to the LVM

LVM components:

'''Physical Volumes (PVs)''' Unused partitions LVM uses to store info

'''A Volume Group (VG)''' Contains one or more PVs. Represents the pool of hard disk storage space that is
available to the LVM for creating logical volumes

'''Logical Volumes (LVs)''' The usable volumes created by the LVM from the storage within a VG. LVs contain a filesystem and are mounted to a directory in the hierarchy. LVs can be resized easily by the LVM to use more or less storage space.

LVM Commands
pvcreate /dev/sda4
pvdisplay
vgcreate vg00 /dev/sda4
vgdisplay
lvcreate –L 15GB –n data vg00
lvdisplay

You then work with these files you created as you would any other partition device file.

==USB and Fireware based storage==
Used because of their large capacity and portability. Devices which typically connect to your PC via high speed USB or Firewire cables are: flash memory drives, external hard drives, digital cameras (that contain flash memory cards), media players.

==Monitoring Filesystems==
Keep at least 10% of the “/” filesystem free otherwise performance can suffer.

/usr should have enough free space for the software you want installed.

/var grows with log files so delete old logs.

/usr grows with what you save there.

Easiest method to monitor free space is to use the df (Disk free) command.

df –h
displays in an easier to read format showing in gigs or megabytes.

df only views mounted filesystems so mount them prior to using df.

If you are running out of space you can use the du command to see directory sizes.

du can be used with | more or less
du -s

will show in a summary format

du -h
will show in gigs and megabytes like df

Filesystem corruption happens on all OS’s
The most common corruption occurs when shutting down a computer and the memory gets saved to the hard drive (known as syncing). Some areas of a hard drive can go bad and not be readable by the system.

To check for errors use the fsck command (filesystem check). If you do not specify a filesystem type it will try to automatically detect one.

'''The filesystem must be UNmounted before you can check it'''

fsck –a or –y
to automatically fix errors

fsck –C
displays a progress line

fsck –f
to perform a full scan, if you do not it will be a quick scan

==Hard Disk Quotas==
If you have a lot of users you might want to limit the amount of disk space they can use
Two types of quotas:

'''Soft Quotas:''' Users can go over their quota for a period of time

'''Hard Quotas:''' Cannot be passed.

quotaon
turns it on

-a for all mounted filesystems

-u or –g for users and groups

quotaoff
turns it off

-u or –g as above

-a ends all quotas

edquota
to edit a quota that exists

repquota
displays quota report

Sources:
[http://www.linux-tutorial.info/modules.php?name=MContent&pageid=243 Supported File Systems]

[http://manpages.ubuntu.com/manpages/hardy/man8/fdisk.8.html fdisk options]

Chapter 7 Study Guide

2012-02-29T21:51:23Z

JBackley: /* Shell Scripts */

==Command input and output==
'''Bash Shell'''
Responsible for providing user interface

Interprets commands entered on command line

Can manipulate command input and output

'''Input and Outputs of commands'''
Represented by labels know as file descriptors. There are 3 file descriptors:

'''Standard input''' (stdin) information processed by the command during execution

'''Standard output''' (stdout) refers to the normal output of a command

'''Standard error''' (stderr) refers to any error messages generated by the command

Both stdout and stderr are displayed on the terminal screen by default

Use the BASH shell to redirect stdout and stderr from the terminal screen to a file on filesystem

Use the > shell metacharacter followed by absolute or relative pathname of the file

ls /etc/hosts /etc/h 1>goodoutput

Use the < to redirect a file to the stdin

cat </etc/issue

Redirection only occurs between a command and a file. However you can send stdout of 1 command to another command as stdin. You can do this by using the pipe shell metacharacter "|" This symbol can be created by pressing the shift key along with the \ key. Common use for piping is to reduce the amount of information displayed.

==Shell variables==
A BASH shell has several variables in memory at one time. A variable is a reserved portion of memory containing info that might be accessed. Most variables in the shell are referred to as environmental variables because they are typically set by the system and contain info that the system and programs access regularly. Users can also create custom variables. Special variables can also be used for executing commands and creating new files and directories.

'''Environmental Variables'''
Many are set by default in the BASH shell. To see a list of these variables and their values use the set command. Other variables used to set the user’s work environment:
PS1 – The default shell prompt

HOME – The absolute pathname to the user’s home directory

PWD – The present working directory in the directory tree

PATH – A list of directories to search for executable programs

'''Home Variable'''
Used by programs that require pathname to the current user’s home directory. If root user logs in, the HOME variable is set to /root. If user logs in, the HOME variable is set to /home/user.

SHOULD NOT BE CHANGED!

''' PWD Variable'''
PWD stores the current user’s location in the directory tree. It is affected by the cd command and used by other commands, such as pwd, when the current directory need to be identified.

SHOULD NOT BE CHANGED!

'''Path Variable'''
One of the most important variables in the BASH shell. It allows users to execute commands by typing the command name alone. If the executable file is in a directory not listed in the PATH variable (such as the /root directory)the user must specify either the absolute or relative pathname to the executable file.

'''User Defined Variables'''
To create a variable, specify the name of the variable followed by = and the new contents. Variable identifies can contain alphanumeric characters, the "–" character, or the "_" character. They must not start with a number. They are typically capitalized to follow convention (HOME, PATH, etc.). To create a variable called MYVAR with the contents “This is a sample variable” you would use these command:
MYVAR="This is a sample variable"

'''Environmental Files'''
To ensure that variables are accssible to a shell at all times, you must place variables in a file that is executed each time a user logs in and starts a BASH shell. These are called environmental files.
Some common BASH shell environment files and the order in which they are executed are:

~/.bashrc Typically used to set aliases and variables that must be present in each BASH shell. It is executed immediately after login for all users as well as when a new BASH shell is created after login

/etc/profile Always executed after login for all users on the system and sets most environmental variables

~/.bash_profile

~/.bash_login

~/.profile

==Shell Scripts==
A set of commands saved in a text file used to automate common tasks. Any command you can use in the command line can be used in a script. hashpling (#! /bin/bash) specifies the pathname to the shell that interprets the script. “#” by itself is a comment in the script.

Sample Script:
#!/bin/bash
#this is a comment
echo “The date is:”
date
echo “ “
echo “People logged in:”
who

'''Escape Sequences''
Used to change output of text in the terminal.

Common ones:
\??? -A 3 digit ASCII character (in octal)
\\ -Backslash
\a –ASCII beep
\b –Backspace
\c –prevents a new line between commands
\n –New Line
\t –Horizontal Tab
\v –Vertical Tab

'''Read Command'''
Saves user’s input and places it in a variable used by a script. In the example the script asks for a name, when you type it in it is saved to the NAME variable.

Echo –e “Who are you? \c”
Read NAME
Echo “Hello $NAME”

Who are you? '''Jason''' <--User's typed response
Hello Jason

'''Decision Constructs'''
Not all scripts will run straight through, sometimes you need to see if something installed or the user typed something. Decision constructs allow a script to do different things in different scenarios.

Format of an If construct:
If “something is true”
Then
Do these commands
Else
Do these commands

Example:

if [ $NAME = “Jason”]
then
echo –e “Hello, Jason”
else
echo –e “Go Away”

If the variable NAME is "Jason" it will say Hello, Jason. If it is anything else it will echo "Go Away"

Test Functions:

-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]

-ne is not equal to 5 != 6 if test 5 -ne 6 if [ 5 -ne 6 ]

-lt is less than 5 < 6 if test 5 -lt 6 if [ 5 -lt 6 ]

-le is less than or equal to 5 <= 6 if test 5 -le 6 if [ 5 -le 6 ]

-gt is greater than 5 > 6 if test 5 -gt 6 if [ 5 -gt 6 ]

-ge is greater than or equal to 5 >= 6 if test 5 -ge 6 if [ 5 -ge 6
]
string1 = string2 string1 is equal to string2

string1 != string2 string1 is NOT equal to string2

string1 string1 is NOT NULL or not defined

-n string1 string1 is NOT NULL and does exist

-z string1 string1 is NULL and does exist-s file Non empty file

-f file Is File exist or normal file and not a directory

-d dir Is Directory exist and not a file

-w file Is writeable file

-r file Is read-only file

-x file Is file is executable

[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]

'''Case Constructs''
You can use the case command for multiple outcomes of a variables Start statement with “Case” End a case statement with “Esac” case backwards

Example:

echo –e “What is the Capital of France?
Milan (a)
Frankfurt (b)
Paris (c)”
read ANSWER
case $ANSWER in
a | A ) echo –e “Incorrect”
,,
b | B) echo –e “Incorrect”
,,
c | C) echo –e “Correct”
,,
esac

Will ask the question "What is the capital of France?" and list 3 choices. The user then types in their response (a | A means it will accept capitalized response or not). If "a", "A", "b", or "B" are typed it will say "Incorrect". If "c" or "C" are typed it will say "Correct".

'''&& and ||'''
&& and || are tests for if a command ran successfully or not

Format: command1 (&& or ||) command2

&& means if command 1 ran then run command2

|| means if command1 did not then run command 2

'''Loops'''
Sometimes you need to run something multiple times. This is what a loop is for. A loop will keep running a set of commands until it is told to stop.

For Loops will run the set commands for each string listed after the variable.

for NAME in bob sue mary jane frank lisa
do
mail –s “here is your schedule” <newschedule $NAME
echo “$NAME was emailed successfully”

This script will email bob, sue, mary, jane, frank, and lisa. It will also print when they are emailed successfully.

While Loops will run while something is true and stop once they become false.

counter=0
while [ $COUNTER –lt 7 ]
do
echo “All work and no play makes Jack a dull boy” >> /tmp/redrum COUNTER=‘expr $COUNTER + 1’
done

This script sets a counter to 0 and then adds 1 to the counter each time the commands are run. It will continue running until the counter is equal to 7. So the output would look like:

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

All work and no play makes Jack a dull boy

[http://www.youtube.com/watch?v=t30ifxc5rtg&feature=related Example Video!]

Chapter 7 Study Guide

2012-02-29T21:48:06Z

JBackley:

2012-02-29T21:26:34Z

JBackley: /* Shell variables */

Chapter 7 Study Guide

2012-02-29T21:24:44Z

JBackley: /* Shell variables */

Chapter 7 Study Guide

2012-02-29T21:19:06Z

JBackley: /* Command input and output */

2012-02-15T01:16:21Z

JBackley:

Chapter 5 Study Guide

2012-02-15T01:10:49Z

JBackley:

Franske CNT-2311 SP12 Chapter Groups

2012-02-13T18:11:33Z

JBackley: /* Chapter 7 */

=Chapter 1=
* N/A - Read on Your Own
=Chapter 2=
*Clay Wilson
*Mike Garin
*Rob Klaers
*Todd Baily
=Chapter 3=
*Randy Oye
*Tracy Ryder
*Dave Litke
*Dan Madigan
=Chapter 4=
*Andrew Powell
*Jesse Bruhn
*Sean Bencker
*Scott Pomerleau
*Laprice Ali
=Chapter 5=
*Thu Nguyen
*Tyler Gray
*Jason Backley
*Matt Obermuelle
=Chapter 6=
*Kevin
*George
*Bill
*Ryan
=Chapter 7=
*Jason Backley
*Tyler Gray
*Matt Obermueller
BAM!!!!!

=Chapter 8=
* Sean Bencker
*laprice ali
* Rob Klaers

=Chapter 9=
*Randy Oye
*Dave Litke
*Tracy Stoltz

=Chapter 10=
*
*
*
=Chapter 11=
*
*
*
=Chapter 12=
* Ben Franske
=Chapter 13=
*
*
*
=Chapter 14=
* Andrew Powell
* Jesse
* Scott

Franske CNT-2311 SP12 Chapter Groups

2012-02-13T18:11:23Z

JBackley: /* Chapter 7 */

=Chapter 1=
* N/A - Read on Your Own
=Chapter 2=
*Clay Wilson
*Mike Garin
*Rob Klaers
*Todd Baily
=Chapter 3=
*Randy Oye
*Tracy Ryder
*Dave Litke
*Dan Madigan
=Chapter 4=
*Andrew Powell
*Jesse Bruhn
*Sean Bencker
*Scott Pomerleau
*Laprice Ali
=Chapter 5=
*Thu Nguyen
*Tyler Gray
*Jason Backley
*Matt Obermuelle
=Chapter 6=
*Kevin
*George
*Bill
*Ryan
=Chapter 7=
This group can only have three members!
*Jason Backley
*Tyler Gray
*Matt Obermueller
BAM!!!!!

=Chapter 8=
* Sean Bencker
*laprice ali
* Rob Klaers

=Chapter 9=
*Randy Oye
*Dave Litke
*Tracy Stoltz

=Chapter 10=
*
*
*
=Chapter 11=
*
*
*
=Chapter 12=
* Ben Franske
=Chapter 13=
*
*
*
=Chapter 14=
* Andrew Powell
* Jesse
* Scott

Chapter 5 Study Guide

2012-02-10T17:25:06Z

JBackley: /* /Dev directoy */

Chapter 5 Study Guide

2012-02-10T17:24:33Z

JBackley:

2011-08-30T21:20:47Z

JBackley: Created page with "=This is just a test= ==sub thingy== ==sub thingy 2== = what does this do?= ==word== ==word== ===wooooord== =hmmmmmmm= ==interesting== ==two equal signs== === 3 equal signs=== 'i..."

=This is just a test=
==sub thingy==
==sub thingy 2==
= what does this do?=
==word==
==word==
===wooooord==
=hmmmmmmm=
==interesting==
==two equal signs==
=== 3 equal signs===
'italic'
''bold''

===test picture===
[[File:chart.png]]

# 1
## 1.1
### 1.1.1?
## two
## two
## two
### three
### three
### three
### three
#### four
#### four
[[File:Example.jpg]]