Arun Bagul – Page 15 – IndianGNU.org

Secure FTP using rssh or scponly with chroot

By Arun Bagul | August 18, 2010 | Comments 0 Comment

Introduction –

In this article we will setup SFTP using rssh with chroot ….

A] How to configure rssh + chroot for SFTP

Step 1) Install RSSH Shell ~

* Ubuntu –

root@me:/home/arunb# apt-get install scponly rssh coreutils17

* Redhat/CentOS

[root@arun.me chroot]# yum install rssh
[root@arun.me chroot]# rpm -qa | grep rssh
rssh-2.3.2-1.2.el5.rf
[root@arun.me chroot]#

Step 2) Your Chroot Setting –

[root@arun.me ~]# cat /etc/rssh.conf
# This is the default rssh config file

logfacility = LOG_USER
###### arun ########
allowsftp
# set the default umask
umask = 022
chrootpath =”/home/chroot”
###### end ########

Step 3) Create user ~

[root@arun.me ~]# mkdir /home/chroot/
[root@arun.me ~]# useradd -d /home/chroot/home/sftp_test -s /usr/bin/rssh sftp_test
[root@arun.me ~]# passwd sftp_test

* Now add following line in “/etc/rssh.conf” file…

user =”sftp_test:022:00010:/home/chroot/sftp_test”

*** [root@arun.me ~]# tail /etc/passwd

sftp_test:x:503:503::/home/chroot/home/sftp_test:/usr/bin/rssh

Step 4) Chroot allow to log via syslogd ~

add following entry in file “/etc/sysconfig/syslog” and restart syslogd

SYSLOGD_OPTIONS=”-m 0 -a /home/chroot/dev/log -a /dev/log”

root@arun.me ~]# /etc/init.d/syslog restart

Step 5) Now setup Chroot ENV –

[root@arun.me ~]# /var/src/arun_rssh_mkchroot.sh /home/chroot/

[root@arun.me ~]# cd /home/chroot/

[root@arun.me chroot]# mknod –mode=600 dev/console c 5 1
[root@arun.me chroot]# mknod –mode=666 dev/null c 1 3

[root@arun.me chroot]# /var/src/arun_shared_lib.sh usr/libexec/openssh/sftp-server

[root@arun.me chroot]# cp /lib/libnss_files.so.2 lib/libnss_files.so.2
[root@arun.me chroot]# cp /lib64/libnss_files.so.2 lib64/libnss_files.so.2

Step 6) Test now ~

arunb@me:~$ sftp sftp_test@192.168.0.1
Connecting to 192.168.0.1…
sftp_test@192.168.0.1’s password:
sftp> pwd
Remote working directory: /home/sftp_test
sftp> ls
arun manoj mayur ravi
sftp>

sftp> ls /
/dev /etc /home /lib /lib64 /usr
sftp>

Step 7) Process for New user ~

a) [root@arun.me chroot]# useradd -d /home/chroot/home/sftp_tmp -s /usr/bin/rssh sftp_tmp
[root@arun.me chroot]# passwd sftp_tmp

b) Add line in file “/etc/rssh.conf”

user =”sftp_tmp:022:00010:/home/chroot”

c) Copy user entry from /etc/{passwd,group,shadow} files TO CHROOT {passwd,group,shadow} files ~

NOTE ~ be careful…

[root@arun.me chroot]# grep sftp_tmp /etc/passwd >> /home/chroot/etc/passwd
[root@arun.me chroot]# grep sftp_tmp /etc/group >> /home/chroot/etc/group
[root@arun.me chroot]# grep sftp_tmp /etc/shadow >> /home/chroot/etc/shadow

[root@arun.me ~]# cat /home/chroot/etc/{passwd,group,shadow}

sftp_tmp:x:504:504::/home/chroot/home/sftp_tmp:/usr/bin/rssh
bin:x:1:bin,daemon
daemon:x:2:bin,daemon
sftp_test:x:503:
sftp_tmp:x:504:
bin:*:14797:0:99999:7:::
daemon:*:14797:0:99999:7:::
sftp_test:$1$Ei5oj.yu$P5FDHHI1POxIIv5562BIm/:14798:0:99999:7:::
sftp_tmp:$1$wZ6Qk3R/$ANRx5MkBA91pjzE/Dr3vK.:14798:0:99999:7:::
[root@arun.me chroot]#

Step 8) Test it now from other linux host

bagul@me:~$ sftp sftp_tmp@192.168.0.1
Connecting to 192.168.0.1…
sftp_tmp@192.168.0.1’s password:
sftp> pwd
Remote working directory: /home/sftp_tmp
sftp>
sftp> ls
sftp> ls
1 2 3 a b c
sftp> pwd
Remote working directory: /home/sftp_tmp
sftp>
sftp>
sftp> ls /
/dev /etc /home /lib /lib64 /usr
sftp> cd /etc
sftp> pwd
Remote working directory: /etc
sftp> ls
group ld.so.cache ld.so.conf localtime nsswitch.conf passwd shadow
sftp>
sftp> get 1
Fetching /home/sftp_tmp/1 to 1
/home/sftp_tmp/1 100% 14 0.0KB/s 00:00
sftp> mkdir arun
sftp> ls
1 2 3 a arun b c
sftp> version
SFTP protocol version 3
sftp> rm c
Removing /home/sftp_tmp/c
sftp>

Step 9) What is required for CHROOT ~

[root@arun.me chroot]# pwd
/home/chroot
[root@arun.me chroot]# ll
drwxr-xr-x 2 root root 4096 Jul 8 07:50 dev
drwxr-xr-x 2 root root 4096 Jul 8 07:50 etc
drwxr-xr-x 4 root root 4096 Jul 8 07:51 home
drwxr-xr-x 2 root root 4096 Jul 8 07:05 lib
drwxr-xr-x 2 root root 4096 Jul 8 07:28 lib64
drwxr-xr-x 5 root root 4096 Jul 8 07:05 usr
[root@arun.me chroot]# ll -ld /home/
drwxr-xr-x 6 root root 4096 Jul 8 08:00 /home/
[root@arun.me chroot]# ll dev/
crw——- 1 root root 5, 1 Jul 8 07:13 console
srw-rw-rw- 1 root root 0 Jul 8 07:50 log
crw-rw-rw- 1 root root 1, 3 Jul 8 07:14 null
[root@arun.me chroot]# ll etc/
-rw-r–r– 1 root root 74 Jul 8 07:55 group
-rw-r–r– 1 root root 81321 Jul 8 07:05 ld.so.cache
-rw-r–r– 1 root root 28 Jul 8 07:05 ld.so.conf
-rw-r–r– 1 root root 3519 Jul 8 07:16 localtime
-rw-r–r– 1 root root 1696 Jul 8 07:16 nsswitch.conf
-rw-r–r– 1 root root 192 Jul 8 07:55 passwd
-r——– 1 root root 180 Jul 8 07:55 shadow
[root@arun.me chroot]# ll lib
-rwxr-xr-x 1 root root 46680 Jul 8 07:28 libnss_files-2.5.so
lrwxrwxrwx 1 root root 19 Jul 8 07:05 libnss_files.so.2 -> libnss_files-2.5.so
[root@arun.me chroot]# ll lib64
-rwxr-xr-x 1 root root 139416 Jul 8 07:10 ld-linux-x86-64.so.2
-rwxr-xr-x 1 root root 10000 Jul 8 07:18 libcom_err.so.2
-rwxr-xr-x 1 root root 1366176 Jul 8 07:18 libcrypto.so.6
-rwxr-xr-x 1 root root 48600 Jul 8 07:18 libcrypt.so.1
-rwxr-xr-x 1 root root 1717800 Jul 8 07:18 libc.so.6
-rwxr-xr-x 1 root root 23360 Jul 8 07:18 libdl.so.2
-rwxr-xr-x 1 root root 9472 Jul 8 07:18 libkeyutils.so.1
-rwxr-xr-x 1 root root 114352 Jul 8 07:18 libnsl.so.1
-rwxr-xr-x 1 root root 53880 Jul 8 07:28 libnss_files.so.2
-rwxr-xr-x 1 root root 145824 Jul 8 07:18 libpthread.so.0
-rwxr-xr-x 1 root root 92736 Jul 8 07:18 libresolv.so.2
-rwxr-xr-x 1 root root 95464 Jul 8 07:18 libselinux.so.1
-rwxr-xr-x 1 root root 247496 Jul 8 07:18 libsepol.so.1
-rwxr-xr-x 1 root root 18152 Jul 8 07:18 libutil.so.1
[root@arun.me chroot]# ll usr/
drwxr-xr-x 2 root root 4096 Jul 8 07:05 bin
drwxr-xr-x 2 root root 4096 Jul 8 07:05 lib64
drwxr-xr-x 3 root root 4096 Jul 8 07:05 libexec
[root@arun.me chroot]# ll usr/bin
-rwxr-xr-x 1 root root 33265 Jul 8 07:05 rssh
-rwxr-xr-x 1 root root 53384 Jul 8 07:05 scp
[root@arun.me chroot]# ll usr/lib64
-rwxr-xr-x 1 root root 190976 Jul 8 07:18 libgssapi_krb5.so.2
-rwxr-xr-x 1 root root 153464 Jul 8 07:18 libk5crypto.so.3
-rwxr-xr-x 1 root root 613896 Jul 8 07:18 libkrb5.so.3
-rwxr-xr-x 1 root root 35728 Jul 8 07:18 libkrb5support.so.0
-rwxr-xr-x 1 root root 229272 Jul 8 07:18 libnspr4.so
-rwxr-xr-x 1 root root 1221496 Jul 8 07:18 libnss3.so
-rwxr-xr-x 1 root root 119696 Jul 8 07:18 libnssutil3.so
-rwxr-xr-x 1 root root 17736 Jul 8 07:18 libplc4.so
-rwxr-xr-x 1 root root 13800 Jul 8 07:18 libplds4.so
-rwxr-xr-x 1 root root 85608 Jul 8 07:18 libz.so.1
[root@arun.me chroot]# ll usr/libexec
drwxr-xr-x 2 root root 4096 Jul 8 07:05 openssh
-rwsr-xr-x 1 root root 69892 Jul 8 07:05 rssh_chroot_helper
[root@arun.me chroot]# ll usr/libexec/openssh
total 56
-rwxr-xr-x 1 root root 53080 Jul 8 07:05 sftp-server
[root@arun.me chroot]#

Thank you,
Arun Bagul

Happy Independence Day ~ 2010

By Arun Bagul | August 15, 2010 | Comments 0 Comment

How to change Xsplash theme in Ubuntu

By Arun Bagul | May 20, 2010 | Comments 0 Comment

Introduction –

Xsplash is the theme which you will see during ubuntu booting process!

Step 1] Go to the directory – “/usr/share/images/xsplash”

root@me:~# cd /usr/share/images/xsplash
root@me:/usr/share/images/xsplash#

*** Take backup of original theme –

root@me:/usr/share/images/xsplash# cp -fr /usr/share/images/xsplash/ /usr/share/images/xsplash-original

Step 2] Download Xsplash themes –

URL – “http://gnome-look.org/content/show.php/Fusion-GX-v00+%5B200911-21%5D?content=115833” OR “http://espiralx.org/05-Compartir/09-Gnome.html”

Step 3] Copy this theme files to /usr/share/images/xsplash/ directory and check the xsplash using ‘xsplash’ command.

root@me:~# xsplash

Thank you,
Arun Bagul

Xen virtualization on CentOS linux

By Arun Bagul | May 14, 2010 | Comments 0 Comment

Introduction ~

What is Virtualization? ~ virtualization is technique of running multiple operating system (OS) on same physical hardware at same time.
There are three types of Virtualization technologies

1) Full virtualization –
a) Hardware emulation – KQEMU
b) Binary translation – VirtualBox
c) Classic virtualization – OpenVZ
2) Para-virtualization
3) OS-level virtualization – Linux-VServer and OpenVZ

** Xen is an open-source para-virtualizing virtual machine monitor (VMM), or “hypervisor”,for a variety of processor. Xen can securely execute multiple virtual machines on a single physical system with near native performance.

** Xen Prerequisites –

1) iproute2 package
2) Linux bridge-utils (/sbin/brctl)
3) Linux hotplug system (/sbin/hotplug and related scripts)

Step 1) How to install Xen on Centos ~

[root@arun ~]# yum install xen.i386 xen-devel.i386 xen-libs.i386 libvirt.i386 libvirt-devel.i386 libvirt-python.i386 virt-manager.i386 virt-clone.i386

Step 2) How to install Xen Kernel for Centos ~

[root@arun ~]# yum install kernel-xen.i686 kernel-xen-devel.i686

* Once installation is completed; Please check the CentOS boot loader configuration file ie “/boot/grub/grub.conf”… and make sure that the first boot entry should look like this…

title CentOS (2.6.18-164.15.1.el5xen)
root (hd0,4)
kernel /boot/xen.gz-2.6.18-164.15.1.el5
module /boot/vmlinuz-2.6.18-164.15.1.el5xen ro root=LABEL=/ rhgb quiet
module /boot/initrd-2.6.18-164.15.1.el5xen.img

Step 3) Reboot the system so that system will boot with Xen Kernel….

That’s it Xen infrastructure is installed on CentOS.

[[root@arun ~]# rpm -qa | egrep “xen|virt” | sort
kernel-xen-2.6.18-164.15.1.el5
kernel-xen-devel-2.6.18-164.15.1.el5
libvirt-0.6.3-20.1.el5_4
libvirt-devel-0.6.3-20.1.el5_4
libvirt-python-0.6.3-20.1.el5_4
python-virtinst-0.400.3-5.el5
virt-manager-0.6.1-8.el5
xen-3.0.3-94.el5_4.3
xen-devel-3.0.3-94.el5_4.3
xen-libs-3.0.3-94.el5_4.3
[[root@arun ~]#
Step 4 ) Test Xen setup – make sure that “libvirtd” service is running

Step 5) Install first Guest CentOS –

* Create Disk as file as shown below….

[[root@arun ~]# dd if=/dev/zero of=/var/xen-disk/centOS.hdd bs=4k seek=2048k count=0
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000191 seconds, 0.0 kB/s
[[root@arun ~]# mke2fs -j /var/xen-disk/centOS.hdd
mke2fs 1.39 (29-May-2006)
/var/xen-disk/centOS.hdd is not a block special device.
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1048576 inodes, 2097152 blocks
104857 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2147483648
64 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[[root@arun ~]# mount -o loop /var/xen-disk/centOS.hdd /mnt/
[[root@arun ~]# df -h
Filesystem            Size Used Avail Use% Mounted on
/dev/sda5              55G   12G   41G 22% /
tmpfs                 829M   12K 829M   1% /dev/shm
/dev/sda2              23G   15G 7.8G 65% /mydata
none                  829M 104K 829M   1% /var/lib/xenstored
/var/xen-disk/centOS.hdd
7.9G 147M 7.4G   2% /mnt
[[root@arun ~]#

* We are going to install guestOS from CD/DVD image so we will export this image via FTP so let us
configure ftp server….

* We have copied Centos CD/DVD in “/home/CentOS5.0/” location….

[root@arun ~]# ls /home/CentOS5.0/
CentOS            RELEASE-NOTES-cz.html RELEASE-NOTES-fr       RELEASE-NOTES-nl.html     repodata
EULA              RELEASE-NOTES-de       RELEASE-NOTES-fr.html RELEASE-NOTES-pt          RPM-GPG-KEY-beta
GPL               RELEASE-NOTES-de.html RELEASE-NOTES-it       RELEASE-NOTES-pt_BR       RPM-GPG-KEY-CentOS-5
images            RELEASE-NOTES-en       RELEASE-NOTES-it.html RELEASE-NOTES-pt_BR.html TRANS.TBL
isolinux          RELEASE-NOTES-en.html RELEASE-NOTES-ja       RELEASE-NOTES-pt.html
NOTES             RELEASE-NOTES-es       RELEASE-NOTES-ja.html RELEASE-NOTES-ru
RELEASE-NOTES-cz RELEASE-NOTES-es.html RELEASE-NOTES-nl       RELEASE-NOTES-ru.html
[root@arun ~]#

* I have changed anonymous FTP home from default one to “/home/CentOS5.0/” Please details below….

[root@arun ~]# grep ftp /etc/passwd
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
[root@arun ~]# vi /etc/passwd
[root@arun ~]# grep ftp /etc/passwd
ftp:x:14:50:FTP User:/home/CentOS5.0:/sbin/nologin
[root@arun ~]#

* Now, restart FTP server and try to access to ftp with IPaddress assigned to bridge “virbr0”. In my case it is “ftp://192.168.122.1”

* Start installation now using “virt-install”

[root@arun ~]# virt-install –name arunOS –os-type=linux –ram=300 –file /var/xen-disk/centOS.hdd –location ftp://192.168.122.1 –nographics –bridge=virbr0

Starting install…

* Welcome to CentOS

<Tab>/<Alt-Tab> between elements | <Space> selects | <F12> next screen

* Welcome to CentOS

<Tab>/<Alt-Tab> between elements | <Space> selects | <F12> next screen

* Welcome to CentOS

<Space>,<+>,<-> selection | <F2> Add drive | <F12> next screen

* Welcome to CentOS

+—————————-+ Partitioning +—————————-+
|                                                                        |
|      Device        Start    End     Size       Type     Mount Point    |
| /dev/xvda                                                            ^ |
|   Free space            1    1045    8192M Free space               # |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      v |
|                                                                        |
|    +—–+   +——+   +——–+   +——+   +—-+   +——+      |
|    | New |   | Edit |   | Delete |   | RAID |   | OK |   | Back |      |
|    +—–+   +——+   +——–+   +——+   +—-+   +——+      |
|                                                                        |
|                                                                        |
+————————————————————————+

F1-Help F2-New F3-Edit F4-Delete F5-Reset F12-OK

* Welcome to CentOS

+—————————-+ Partitioning +—————————-+
|                                                                        |
|      Device        Start    End     Size       Type     Mount Point    |
| /dev/xvda                                                            ^ |
|   xvda1                 1     829    6502M ext3        /            # |
|   xvda2               830     893     502M swap                     : |
|   Free space          894    1044    1184M Free space               : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      : |
|                                                                      v |
|                                                                        |
|    +—–+   +——+   +——–+   +——+   +—-+   +——+      |
|    | New |   | Edit |   | Delete |   | RAID |   | OK |   | Back |      |
|    +—–+   +——+   +——–+   +——+   +—-+   +——+      |
|                                                                        |
|                                                                        |
+————————————————————————+

F1-Help F2-New F3-Edit F4-Delete F5-Reset F12-OK

* Same way configure TZ,root password,packages,boot loader options etc…

* Welcome to CentOS

+———————+ Formatting +———————-+
|                                                         |
| Formatting / file system…                             |
|                                                         |
|                           70%                           |
|                                                         |
+———————————————————+

<Tab>/<Alt-Tab> between elements | <Space> selects | <F12> next screen

That’s it!

Thank you,
Arun Bagul

What’s new in GRUB-2?

By Arun Bagul | April 19, 2010 | Comments 0 Comment

Introduction ~ GRUB is perfect boot loader for Linux/Unix system! GRUB-2 supports several features that are important for every system admin.

* Platform support – GRUB 2 is intended to work across a wider range of architectures.
* Partition tables – GRUB-2 supports MBR partitioning scheme and GUID Partition Table (GPT).
* RAID and LVM – Now GRUB is supports both redundant array of independent disks (RAID) and Logical Volume Manager (LVM).
* File system support – GRUB 2 supports some additional non-Linux file systems, such as Apple’s Hierarchical File System Plus, NTFS and ZFS file systems…

* Configuring GRUB 2 –

GRUB 2 configuration file is different from legacy GRUB….

The default location for the GRUB 2 configuration file is /boot/grub/grub.cfg

* Sample GRUB 2 configuration file

root@me:~# cat /boot/grub/grub.cfg

set timeout=10
set default=0

menuentry “Ubuntu, Linux 2.6.31-20-generic” {
set quiet=1
insmod ext2
set root=(hd0,6)
search –no-floppy –fs-uuid –set 7699852c-2a04-4da2-82e8-a69969f16bf2
linux /boot/vmlinuz-2.6.31-20-generic root=UUID=7699852c-2a04-4da2-82e8-a69969f16bf2 ro quiet splash
initrd /boot/initrd.img-2.6.31-20-generic
}

Thanks,
Arun Bagul

How to install GNOME themes in Ubuntu

By Arun Bagul | March 9, 2010 | Comments 0 Comment

Introduction – There are many beautiful GNOME desktop themes available for Ubuntu and other linux….

Step 1] Add repository –

root@me:~# add-apt-repository ppa:bisigi/ppa

*** Add following two lines in “/etc/apt/sources.list” file.

root@me:~# vi /etc/apt/sources.list

deb http://ppa.launchpad.net/bisigi/ppa/ubuntu karmic main
deb-src http://ppa.launchpad.net/bisigi/ppa/ubuntu karmic main

Step 2] Add the gpg key of repository –

root@me:~# gpg –keyserver hkp://keyserver.ubuntu.com:11371 –recv-key 881574DE && gpg -a –export 881574DE | apt-key add –

Step 3] Update the repo list and install the themes….

root@me:~# apt-get update

* To install all available themes plz run this command….

root@me:~# apt-get install bisigi-themes

* To install indivisual themes.. (few best themes)

root@me:~# apt-get install showtime-theme

root@me:~# apt-get install balanzan-theme
root@me:~# apt-get install infinity-theme
root@me:~# apt-get install wild-shine-theme
root@me:~# apt-get install tropical-theme
root@me:~# apt-get install ubuntu-sunrise-theme
root@me:~# apt-get install aquadreams-theme

Step 4] How to activate/select theme.

Go to “System” –> “Preferences” –> “Appearance” and select your theme!!

** Enjoy

Thank you,
Arun Bagul

Как установить & настроить VNC Server на CentOS

By Arun Bagul | January 15, 2010 | Comments 0 Comment

Как установить VNCSERVER На CentOS

Yum groupinstall “GNOME Desktop Environment”
Yum Xterm Установить VNC-сервера VNC

удалить существующий файл с править & ‘/ ETC / sysconfig / VNCSERVERS “и добавьте следующие строки в нем

VNCSERVERS = “2: Root”
VNCSERVERARGS [2] = “-геометрия 800 × 600-nolisten TCP-nohttpd-LocalHost”

установить VNC пароль для открытия VNC для пользователей корня (Вы должны Войти как корень)
vncpasswd

установить VNC пароль для открытия VNC для пользователей (Вы должны Войти как обычный пользователь, как это создаст файл Xstartup в $ HOME / .vnc)
vncpasswd

Теперь запустите vncserver качестве суперпользователя
/ и т.д. / init.d / vncserver начало

Теперь убейте vncserver proocesses используя ‘PS AUX | Grep VNC | xargs убить -9’
Введение ~
и начать VNC Server, выполнив команду
vncserver

проверить указанный путь, чтобы открыть VNC-дисплей в качестве примера приводятся в
Appserver.ravi.com Новая ‘: 3 (корень)’ рабочий стол appserver.ravi.com: 3

Перед открытой VNCViewer удалить файл ‘/ tmp/.X1-lock’

Теперь откройте VNC дисплее вы получите по умолчанию ‘Xterm “открытые на нем.

Спасибо,
Рави Bhure

Happy New Year 2010!

By Arun Bagul | January 1, 2010 | Comments 1 comment

Dear All,

We wish you Happy new year 2010 to all of you!

Regards,

IndianGNU.org & openlsm

Happy New Year 2010!

By Arun Bagul | January 1, 2010 | Comments 0 Comment

Dear All,

We wish you Happy new year 2010 to all of you!

Regards,

IndianGNU.org & openlsm

BASH Scripting ~ learning by examples

By Arun Bagul | December 31, 2009 | Comments 1 comment

Introduction ~

—————————————–
Program (1) ~ array.sh
—————————————–

#!/bin/bash
echo “==============”
declare -a myarr[0]=”Arun”
declare -a myarr1
myarr1=(arun bagul bangalore mumbai raju santhosh)
myarr[1]=”Bagul”

echo “my name is ${myarr[0]} ${myarr[1]}”
echo “————————–”
echo “${myarr1[*]}”
echo ${myarr1[2]}
echo ${myarr1[@]}
echo “————————–”
echo “Total no of elements in array – ${#myarr1[*]}”
echo “Total no of elements in array – ${#myarr1[@]}”
echo “Size of word ‘${myarr1[2]}’ is – ${#myarr1[2]}”
echo ${#myarr1[1]}
echo ${#myarr1[0]}

echo “————————–”

#how to delete element in array
unset myarr[1]
echo “myarr is – ${myarr[*]}”

#how to assign element in array
myarr[1]=”- System Engineer!”
echo “myarr is – ${myarr[*]}”

echo ${myarr}

————————————————————————
Program (2) ~ command_line_arguments.sh
————————————————————————

#!/bin/bash

echo “Script/command name => $0”
echo “arg1 => $1”
echo “arg2 => $2”
echo “arg3 => $3”
echo “Total No of argument = $#”

echo “Script PID is => $$”
echo “Status of previous command – $?”

name=$myname
echo “Name – $name”

read n

————————————————-
Program (3) ~ default_value.sh
————————————————-

#!/bin/bash

#start=’123′
#start=${1:-$start}

start=${1:-‘123’}

echo “Value of ‘start’ variable is ==> $start”

—————————————————
Program (4) ~ echo_example.sh
—————————————————

#!/bin/bash

name=”Arun”

echo -e “My Name is $name_arun and \n”
echo -e “My Name is ${name}_arun and \n”

echo -e ‘My Name is $name and \n’

—————————————–
Program (5) ~ elif.sh
—————————————–

#! /bin/bash

if [ $1 -eq $2 ];then
echo “good”
elif [ $2 -eq $3 ];then
echo “Fine”
elif [ $1 -eq $3 ];then
echo “OK”
else
echo “NO”
fi

————————————————————
Program (6) ~ for_loop_example-1.sh
————————————————————

#!/bin/bash

i=1
while [ $i -le 512 ]
do
temp=$i
echo “What is => $i | $temp”
i=$(expr $i + 32)
for (( j=$temp; $j<=$i; j++ ))
do
echo -n ” $j”
done
done

———————————————————–
Program (7) ~ for_loop_example-2.sh
———————————————————–

#!/bin/bash
#for val in $(ls -1 /tmp)
sum=0
#for val in {1..5}
#for val in {$1..$2}
for((val=$1;$val<=$2;val++))
do
#echo “$val”
sum=$(expr $sum + $val )
#sum=`expr $sum + $val`
done

echo “$0 # Sum of $1 to $2 => $sum”

————————————————————
Program (8) ~ for_loop_example-3.sh
————————————————————

#!/bin/bash

for i in {1..9}
do
echo $i
done

—————————————–
Program (9) ~ function.sh
—————————————–

#!/bin/bash

function my_function()
{
name=”Arun Bagul”
echo “‘my_function’ body ~ $name”
return 1;
}
##########

myfunc()
{
echo “Another way of defining the function”
}

##########################

echo “Starting function program”
echo “——————————”

#calling function here
my_function
##
myfunc

echo -e “\n end of program”

—————————————————————————————
Program (10) ~ how_to_pass_argument_to_function.sh
—————————————————————————————

#!/bin/bash

function my_function()
{
echo “Total number of argument ~ $#”
echo “Arg1 => $1”
echo “Arg2 => $2”
echo “Arg3 => $3”
return 0;
}
##########

echo “Starting function program”
echo “——————————”

#calling function here
my_function arun bagul 1234

————————————————————————-
Program (11) ~ how_to_take_hidden_input.sh
————————————————————————-

#!/bin/bash

echo -n “Enter User Name :”
read username
echo -n “Enter Password :”
read -s mypwd

echo -e “\nI am $username and my password is – $mypwd”

——————————————————————————
Program (12) ~ how_to_take_input_from_user.sh
—————————————————————————–

#!/bin/bash

echo -ne “Enter the Name:- ”
read name
echo -n -e “Enter the Number:- ”
read num

echo “——————————”

add=$(expr $num + 10)

echo “Name is ~ $name”
echo “Number is ~ $add”

—————————————–
Program (13) ~ ifthen.sh
—————————————–

#!/bin/bash

if [ “arun” == “arun” ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ 2 == 2 ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ “arun” = “arun” ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ 2 -eq 2 ];then
echo “true!”
else
echo “false”
fi

——————————————————
Program (14) ~ non-interactive.sh
——————————————————

#!/usr/bin/expect -f
spawn ssh arun@192.168.0.1
expect “password:”
sleep 1
send “pwd\r”
interact

—————————————————————-
Program (15) ~ read_file_line_by_line.sh
—————————————————————-

#!/bin/bash

file_name=”/etc/hosts”

while read myvar
do
echo “Line => $myvar”
done < $file_name

echo “#################################################”

for myvar1 in $(cat $file_name)
do
echo “Line => $myvar1”
done

——————————————————
Program (16) ~ reverse-number.sh
——————————————————

#!/bin/bash

declare -a date_array
num=$1
i=$(expr $(echo $num | wc -c) – 1 )

while [ $num -gt 10 ]
do
temp=$( expr $num % 10 )
num=$( expr $num / 10);
echo “Digit($i) => $temp”
date_array[$i]=”${temp}”
i=$(expr $i – 1)
done
echo “Digit($i) => $num”
date_array[$i]=”${num}”

echo ${date_array[*]}

——————————————————–
Program (17) ~ string-operation.sh
——————————————————–

#! /bin/bash

echo “Arun Bagul:-”
string=”/root/arun/bagul/image.gif”
echo “string=> $string”
echo “String=> ${string##/*/}”
echo “String=> ${string#/*/}”

echo “String=> ${string%.*}”
echo “String=> ${string%%.*}”
#str=”/home/y/conf/arunbagul/daily_market_0.conf”
str=”${str##/*conf/}”
echo “String=> ${str%/*}”

#done

mystr=”keyword_summary_exact_arunsb”
echo $mystr
echo ${mystr%_*}

echo “$*”

—————————————–
Program (18) ~ switch.sh
—————————————–

#!/bin/bash

echo ” Switch program | arg1 => $1″
echo ” ——————————-”
case $1 in

123)
echo “Case is 123”
;;

arun)
echo “Case is ‘arun'”
;;

pri*)

echo “Case is ‘pri*'”
;;

*)
echo ” * Usage: $0 ”
echo ” Default case (nothing is matched)”
exit 0;
;;
esac

—————————————————————–
Program (19) ~ while_loop_example-1.sh
——————————————————————

#!/bin/bash

mywait=wait

while [ “${mywait}” = “wait” ]
do
echo “arun”
done

——————————————————————-
Program (20) ~ while_loop_example-2.sh
——————————————————————–

#! /bin/bash

## on command line -> i=0 && while [ $i -le 10 ] ; do echo $i; i=$(expr $i + 1); done

i=0
while [ $i -le 10 ]
do
echo $i
i=$(expr $i + 1)
done

——————————————————————–

* Please download PDF file http://www.slideshare.net/arunbagul/bash-learning-by-examples/

Regards,
Arun