Session5 Theory

8/11/2019 Session5 Theory

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ADVANTAGE PROChennais Premier Networking Training Centre


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Partitioning

In Linux, partitions can be created by either of the following three

utilities

fdisksfdisk

disk druid (only available during installation)

GNU parted


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fdisk

fdisk

- Fixed Disk

- Menu driven programs to create and delete partitions

Before starting fdisk, identify the hard disk type that is whether

primary master or slave and secondary master or slave by using

command fdisk -l.


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Red Hat Linux Filesystems

Red Hat supports following filesystems.

- ext2

- ext3

- minux

- reiserFS (under research)


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ext filesystems

ext : Extended filesystem.

ext2 : Older standard Linux file system supporting for filenames

and large file sizes.

ext3 : Standard Red Hat Linux file system, used for all hard disk

volumes under Red Hat Linux by default.

It is the extension of ext2 with the feature of journaling (aware ofunexpected power outages and disk errors)


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minux & reiserFS

Minux : This file system is small , simple and mostly used for

floppy disk .It support filenames up to 30 characters.

ReiserFS : It is advanced journaling filesystem still under

development for Linux.

Its main difference between ext3 and reiserFS .Its use disk

resource efficiently and is particularly effective with file system

containing many small files and large directories


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Creating file system

Once you create a partition, you have to create a file system on it.

To do this, use the mkfs command. To build the Linux file system

and pass the name of the harddisk partition as a parameter.

Syntax:

mkfs -t



Creation of file system

Current partitions are

displayed here



`

Hdb6,7and 8 are

newly created

partitions.


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To view the file system type

Dumpe2fs : this command is used to view which file system we are

using.

Syntax :

dumpe2fs

Example:

dumpe2fs /dev/hda1



To view the file system type

It displays the file

system

information's.

Sparse_superrepresents the

ext2 file system.


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Tune2fs command

tune2fs : It is a command used to converting from ext2 to ext3

file system without un mounting..

Syntax :

tune2fs j

Example

tune2fs -j /dev/hda1


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View the file system type.

Ext2 is the current file

system for the device

hdb6.


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Repair Filesystem

e2fsck : This command checks the consistency of the file system and

repair it if it is damaged, you can use file system checking tools.

Example : e2fsck /dev/hda1fsck : This command checks and repair a Linux file system.

Example : fsck /dev/hda1

The main difference is e2fsck it will work in ext2 and ext3 filesystem

and fsck will work only in ext3 file system.


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Repair Filesystem

fsck and e2fsck are

the command used to

check and repair the

file system.


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Disk usage

df and du are used to check the disk usage.

df : It reports the amount of space used and available on a

mount file system as reported.

du : It displays directories entries and the number of data block

assigned to them.


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Performance tools

free command lists the free ram memory and as well as what is used for

buffers and swap memory.

top command lists the most CPU intensive processes.

Vmstat shows the performance of system components.


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Some process start at boot time and continue running until thesystem is shutdown. Such process are known as daemon processes.

Two types of daemon process:

standalone daemon

Transient daemon

Daemon Process


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Standalone daemon are a program that run all the time and are

started up either directly by init or by a startup script under /etc/rc.d.

Transient daemon are only started up when they are needed, and are

controlled by a standalone daemon called xinetd.

Daemon Process


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chkconfig command

The chkconfig command can also be used to activate and deactivate

services.

The chkconfig --list command displays a list of system services and

whether they are started (on) or stopped (off) in runlevels 0-6.

At the end of the list is a section for the services managed by

xinetd.


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chkconfig can also be used to configure a service to be started (or

not) in a specific run level. For example, to turn httpd off inrunlevels 3, 4, and 5, use the following command:

chkconfig --level 345 httpd off

chkconfig command


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Mount command

Mount

-Used to mount a file system

-It takes two argument : the storage device and the

mounting point.

-The device is a special device file that connects the system

to the hardware device.

- Mounting point is directory on which the storage device is

to be mounted.


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Syntax:

mount [options]

Options:

-w mount the file system with read/write permission.

-r mount the file system with read permission.

-t to specify the type of file system to be mounted.

-a mounts all the file systems listed in /etc/fstab.

Mount command


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umount command

It un mounts the mounted file system.

The removable media like floppy disk, and cd are un mounted

after use, by using umount command.

Syntax:

umount


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Mounting CD-ROM

To mount the

CDROM on the

mounting point/mnt/cdrom


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Mounting CD-ROM

Now we can access the

CDROM contents from

the mounting point.


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Unmounting cd-rom

Unmount the

CDROM after

access


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Unmounting cd-ROM

To eject the

CD from the

CD Drive.


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Mount /unmount floppy

To mount the

floppy on the

mounting point/mnt/floppy.

Unmount the

floppy after

access.


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File Compressions

Several compression utilities are available for use on Linux and

Unix system.

But most software for Linux system use three compression

utilities.

1 - compress

2 - GNU gzip

3 - bzip2.


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Compression command

This

compresses

the file a.

The actual

size of file is

107 bytes.

Thus the file size is

compressed to 39

bytes.

The compressed file is

indicated by the .z

extension.

This

uncompressthe file a.


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Compression with gzip

gzip utility compresses file .

gunzip decompresses them.

To compress a file, enter the command gzip and the filename.this

replace the file with compressed version of it,with the extension .gz.

To decompresses a gzip file use command gunzip.

Syntax:

gzip filename (compression)

gunzip filename.gz (decompression)


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Compression with gzip

The actual

size of file is

107 bytes.gzip command

compresses the

file a.


indicated by the .gz

extension.


compressed to 38bytes.

Thisuncompress

the file a.

C i ith b i 2


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It compresses files using the burrows-wheeler block-sorting text

compression algorithm and huffman coding.You compresses files using the bzip2 command and decompresses

with bunzip2.

The bzip2 command create a file with the extension .bz2

Syntax:

bzip2 filename (compression)

bunzip2 filename.bz2 (decompression)

Compression with bzip2


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Compression with bzip2

This

uncompressthe file a .

The actual

size of file is

107 bytes.bzip2 command

compresses the file

a.


indicated by the .bz2

extension.


compressed to 51

bytes.

i hi


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Creating Archives

Tar:

tar command is used to create archives on device or files.

Originally, tar was used to create archives on tape devices, hence

its name stands for tape archive.When creating a file for a tar archive, the filename is usually

given the extension .tar.

While tar is seldom used to back up entire file system.

S f d


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Syntax for tar command

Syntax for tar command:

tar [option] archivename.tar filenames- and-directories

Options:

c - create new archive.

v - produce verbose message.

f - archivename,a name of new file.

x - archive will be extracted in the current directory.

t - displays a list of file in the archive

d


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tar command

tf options

display all the

file in backup .

tvf options

displays along

with the userand group

names.


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Session5 Theory