how to block multiple hits in same ip in nginx

ref.  https://serverfault.com/questions/611311/restricting-multiple-directories-to-same-ip-ranges

Nagios Setup on centos

Prerequisites
yum install httpd php gcc glibc glibc-common gd gd-devel

Accounts:
/usr/sbin/useradd -m nagios
passwd nagios
/usr/sbin/groupadd nagcmd # Used for Web Interface
/usr/sbin/usermod -a -G nagcmd nagios
/usr/sbin/usermod -a -G nagcmd apache

Download source code
wget https://sourceforge.net/projects/nagios/files/nagios-4.x/nagios-4.1.1/nagios-4.1.1.tar.gz
wget http://www.nagios-plugins.org/download/nagios-plugins-2.1.1.tar.gz

Extract the Nagios source code tarball.
tar -xvzf nagios-4.1.1.tar.gz
cd nagios-4.1.1

Run the Nagios configure and compile source code
./configure --with-command-group=nagcmd
make all
make install
make install-init
make install-config
make install-commandmode

vi /usr/local/nagios/etc/objects/contacts.cfg
Change email address assoicated with install

Nagios web config file

make install-webconf

nagiosadmin account for Nagios web interface

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

service httpd restart

Install the Nagios Plugins
tar xzf nagios-plugins-2.1.1.tar.gz
cd nagios-plugins-2.1.1

./configure --with-nagios-user=nagios --with-nagios-group=nagios
make
make install

Add Nagios services
chkconfig --add nagios
chkconfig nagios on

Verify the sample Nagios configuration files.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
service nagios start


Check SELinux
getenforce

Change to permissive mode.
setenforce 0

Modifiy /etc/selinux/config for system to remain in permission mode

OR  modifiy selinux permissions to allow nagios

chcon -R -t httpd_sys_content_t /usr/local/nagios/sbin/
chcon -R -t httpd_sys_content_t /usr/local/nagios/share/

Log into Nagios web interface
username: nagiosadmin
password: set with htpasswd util

http://localhost/nagios/

iptables
modify /etc/sysconfig/iptables to allow 80 & 443

How to Restrict SFTP Users to Home Directories Using chroot Jail

ref. https://www.tecmint.com/restrict-sftp-user-home-directories-using-chroot/

Git error : The requested URL returned :403 code

This error can appear when the VMware Authorization service is stopped or when the service does not have administrator rights

.

To fix this problem, you just start the service and make sure that it does have administrator rights.

To start the VMware Authorization service

• Press Windows Key + X and type services.msc and click OK.
• Scroll down the list and find that the VMware Authorization service.
• Click Start the service, unless the service is already is showing a status of Started.

usdo access

edit visudo file

## Drivers
# Cmnd_Alias DRIVERS = /sbin/modprobe
######################################
Cmnd_Alias MYCOM = /usr/bin/docker, /usr/bin/git, /usr/bin/systemctl  ---- add command and give
#####################################                                                     driver name



# User_Alias ADMINS = jsmith, mikem

########################################################
User_Alias THY = devops, admin, dev-team   -------  add users
######################################################

## Allow root to run any commands anywhere
###############################
THY ALL=(ALL) MYCOM
###############################

ansible

ref. https://docs.ansible.com/ansible/latest/modules/copy_module.html

How to Install MySQL on CentOS 7 version 5.6

Ref links only 

https://www.linode.com/docs/databases/mysql/how-to-install-mysql-on-centos-7/

https://www.tecmint.com/install-php-5-6-on-centos-7/

yum  install php-mysqlnd php-pgsql php-fpm php-pecl-mongo php-pdo php-pecl-memcache php-pecl-memcached php-gd php-xml php-mbstring php-mcrypt php-pecl-apcu php-cli php-pear
 

how-to-install-sonarqube-on-centos 7

Ref link only : 

https://thegeeksalive.com/how-to-install-sonarqube-on-centos/

https://www.howtoforge.com/tutorial/how-to-install-sonarqube-on-ubuntu-1604/


https://www.howtoforge.com/how-to-install-sonarqube-on-ubuntu-1804/


https://www.vultr.com/docs/how-to-install-sonarqube-on-ubuntu-16-04

How can I fix “cannot find a valid baseurl for repo” errors on CentOS?

URl Ref : https://unix.stackexchange.com/questions/22924/how-can-i-fix-cannot-find-a-valid-baseurl-for-repo-errors-on-centos


dhclient

Tips / Nginx

Nginx Benchmarking using Siedge

Ref : https://www.scalescale.com/tips/nginx/nginx-benchmarking-using-siedge/#

Web-based Source Code Vulnerability Scanner http://dpnishant.github.io/raptor

Ref : https://github.com/dpnishant/raptor

Security Controls

https://docs.nginx.com/nginx/admin-guide/security-controls/

https://gist.github.com/plentz/6737338

https://www.cyberciti.biz/tips/linux-unix-bsd-nginx-webserver-security.html

https://geekflare.com/nginx-webserver-security-hardening-guide/

Why do I receive the error "ERR_TOO_MANY_REDIRECTS" when redirecting HTTP traffic to HTTPS on my Classic Load Balancer?

REF : https://aws.amazon.com/premiumsupport/knowledge-center/redirect-http-https-elb/

Interview questions on docker and kubernetes

Basic Kubernetes Interview Questions

Ref : https://www.edureka.co/blog/interview-questions/kubernetes-interview-questions/

Ref . : https://www.wisdomjobs.com/e-university/docker-software-interview-questions.html

Ref : https://www.javainuse.com/devops/kubernetes_intvw

ref : https://intellipaat.com/interview-question/kubernetes-interview-questions/

ref : https://www.mytectra.com/interview-question/docker-interview-questions/

Ref : https://tekslate.com/docker-interview-questions/

ref : https://www.quora.com/What-are-the-popular-Docker-interview-questions

ref : https://mindmajix.com/docker-interview-questions

reff :https://codingcompiler.com/kubernetes-interview-questions-answers/

How to Install PHP 7.2, Composer , npm, nodejs, mongodb & mongidb extenston on CentOS 7

npm : 3.10.10    

node : v6.16.0
https://www.rosehosting.com/blog/how-to-install-node-js-and-npm-on-centos-7/


php command package conflict issue
https://webtatic.com/packages/php56/


###Install docker community edition on centos 7
https://docs.docker.com/install/linux/docker-ce/centos/#os-requirements

###composer issue
yum install php-mbstring

Install nginx on centos 7
https://www.nginx.com/resources/wiki/start/topics/tutorials/install/
https://www.tecmint.com/install-nginx-on-centos-7/
https://www.cyberciti.biz/faq/how-to-install-and-use-nginx-on-centos-7-rhel-7/

mongo db installation link
https://www.digitalocean.com/community/tutorials/how-to-install-mongodb-on-centos-7
https://www.linode.com/docs/databases/mongodb/install-mongodb-on-centos-7/
https://linuxize.com/post/how-to-install-mongodb-on-centos-7/
https://docs.mongodb.com/manual/tutorial/install-mongodb-on-red-hat/

How to Install PHP 7.2 on CentOS 7

Ref : https://www.tecmint.com/install-php-7-in-centos-7/
yum install php-mbstring

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-lamp-amazon-linux-2.html

https://www.rosehosting.com/blog/how-to-install-php-7-2-on-centos-7/

 How to install PHP MongoDB driver for Linux?

 Ref : https://support.plesk.com/hc/en-us/articles/213916565-How-to-install-PHP-MongoDB-driver-for-Linux-

yum install php-pear

yum install php-devel

pecl install mongodb 

How To Install and Use Composer on CentOS 7 

https://tecadmin.net/install-php-composer-on-centos/

How To Install Latest Nodejs on CentOS/RHEL 7/6 

https://tecadmin.net/install-latest-nodejs-and-npm-on-centos/

centos7 command
https://www.thegeekdiary.com/centos-rhel-7-how-to-check-the-status-of-a-service-using-systemd/

  Change time zone UTC to IST

https://tecadmin.net/change-timezone-on-centos-and-redhat/

  https://hub.docker.com/_/mongo/

https://www.howtoforge.com/tutorial/how-to-install-and-configure-mongodb-on-centos-7/ 

https://blog.whabash.com/posts/installing-supervisor-manage-laravel-queue-processes-ubuntu

  https://gist.github.com/Integralist/72161a96641fa4a0033d

https://gist.github.com/todgru/14768fb2d8a82ab3f436

 https://www.tutorialspoint.com/redis/redis_lists.htm

https://stackoverflow.com/questions/41615574/mongodb-server-has-startup-warnings-access-control-is-not-enabled-for-the-dat

Enabling the Public-DNS of EC2 Instance

Have a look at the step-by-step instructions: For Enabling the Public-DNS of EC2 Instance

Go to console.aws.amazon.com
Go To Services -> VPC
Open Your VPCs
select your VPC connected to your EC2 and
select Actions => Edit DNS Hostnames ---> Change DNS hostnames: to YES

error package docker-ce requires container-selinux = 2.9 centos 7

yum list | grep docker-ce

yum remove docker \
                  docker-common \
                  container-selinux \
                  docker-selinux \
                  docker-engine

yum install --setopt=obsoletes=0 \
     docker-ce-17.03.2.ce-1.el7.centos.x86_64 \
     docker-ce-selinux-17.03.2.ce-1.el7.centos.noarch

ref : https://github.com/docker/for-linux/issues/20

Ref : https://docs.docker.com/install/linux/docker-ce/centos/#uninstall-old-versions

Earning Linux is very easy, Just follow the sequence below.

1. Introduction to Linux -- http://bit.ly/Introcudtion_to_Linux

2. Linux Architecture -- http://bit.ly/Linux_Architecture

3. Windows Vs Linux Comparision -- http://bit.ly/Windows_Vs_Linux

4. Bash Shell features -- http://bit.ly/bash_shell

5. Linux Directory Structure -- http://bit.ly/Linux_Directory_structure

6. Linux Boot Process Detailed explanation - http://bit.ly/LinuXboot_process

7. Basic and Common Commands - http://bit.ly/Basicommands

8. All Linux Commands with there description - http://bit.ly/Linux_commands

9. Linux Text Editors - http://bit.ly/Text_Editors

10. Linux Operating System Installation - http://bit.ly/Linux_OS_Installation

11. User Profile Management - http://bit.ly/User_Profile_management

12. User Administration (User Creation, Modification and deletion) - http://bit.ly/User_Administration

13. Access Control List - http://bit.ly/Linux_acl

14. Head, Sort, Tail, Uniq, Paste, Cut, Tr, Sed and diff commands with examples - http://bit.ly/String_commands

15. Soft Link Vs Hard Link - http://bit.ly/Soft_vs_hard_link

16. Search related commands Grep, find and locate - http://bit.ly/search_commands

17. Task Automation using crontab and at - http://bit.ly/Linux_crontab

18. File system and Creating Standard partitions - http://bit.ly/Creating_partition

19. Logical Volume Manager (LVM - Part1) - http://bit.ly/Linux_LVM

20. Logical Volume Manager (LVM - Part2) - http://bit.ly/Linux_LVM2

21. Disk quota management - http://bit.ly/Disk_quota

22. RPM / YUM - http://bit.ly/Linux_YUM

23. All RAID Levels explained - http://bit.ly/RAID_Levels

24. Creating and Managing Software RAID - http://bit.ly/Manage_RAID

25. Neworking installing and configuring the Network Card - http://bit.ly/Linux_networking

26. Remote Server Management (VNC Server) - http://bit.ly/Remote_server

27. Network File System (NFS) - http://bit.ly/TT_NFS

28. Samba Server (SMB) - http://bit.ly/sambaServer

29. File Transfer Protocol (FTP) - http://bit.ly/FileServerFTP

30. Web Server / Apache (HTTPD) - http://bit.ly/WEBServer

31. Mail Server configuration (SMTP) - http://bit.ly/1QopUJy

32. DHCP Server installation and configuration - http://bit.ly/1HLeHQu

33. DNS Server installation and configuration - http://bit.ly/1H2F7Nw

34. NIS Server - http://bit.ly/1NxgsgE

35. PAM - http://bit.ly/1MPioAB

36. Backup and Restore - http://bit.ly/1PtQl0c

37. SQUID Proxy Server - http://bit.ly/1SQUNoo

38. VNC Server - Centos - http://bit.ly/1WThXAf

39. Recovering ROOT Password - http://bit.ly/1kW6tuv

40. Netapp MPIO installation and configuration in Linux - http://bit.ly/1O9nsTL

41. Local YUM Server configuration - http://bit.ly/1lpfjBm

42. Kick Start Server installation and configuration - http://bit.ly/1SQVfmw

43. Process Management - http://bit.ly/1kW70fO

 

Interview questions and answers - PArt1- http://bit.ly/1NRnpMv

Interview questions and answers - PArt2 - http://bit.ly/1NtRXp9

Interview questions and answers - PAr3 - http://bit.ly/1Sr7juF

mount: Arugument list too Long - http://bit.ly/1Lg4qqm

Book Linux Hands on Guide - http://bit.ly/1MeDyuH

Rsync (Remote Sync): 10 Practical Examples of Rsync Command in Linux

rsync is a file transfer program capable of efficient remote update via a fast differencing algorithm.Usage: rsync [OPTION]... SRC [SRC]... DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST:DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST::DEST
  or   rsync [OPTION]... SRC [SRC]... rsync://[USER@]HOST[:PORT]/DEST
  or   rsync [OPTION]... [USER@]HOST:SRC [DEST]
  or   rsync [OPTION]... [USER@]HOST::SRC [DEST]
  or   rsync [OPTION]... rsync://[USER@]HOST[:PORT]/SRC [DEST]
The ':' usages connect via remote shell, while '::' & 'rsync://' usages connect
to an rsync daemon, and require SRC or DEST to start with a module name.

Options
-v, --verbose	increase verbosity
-q, --quiet	suppress non-error messages
--no-motd	suppress daemon-mode MOTD (see manpage caveat)
-c, --checksum	skip based on checksum, not mod-time & size
-a, --archive	archive mode; equals -rlptgoD (no -H,-A,-X)
--no-OPTION	turn off an implied OPTION (e.g. --no-D)
-r, --recursive	recurse into directories
-R, --relative	use relative path names
--no-implied-dirs	don't send implied dirs with --relative
-b, --backup	make backups (see --suffix & --backup-dir)
--backup-dir=DIR	make backups into hierarchy based in DIR
--suffix=SUFFIX	set backup suffix (default ~ w/o --backup-dir)
-u, --update	skip files that are newer on the receiver
--inplace	update destination files in-place (SEE MAN PAGE)
--append	append data onto shorter files
--append-verify	like --append, but with old data in file checksum
-d, --dirs	transfer directories without recursing
-l, --links	copy symlinks as symlinks
-L, --copy-links	transform symlink into referent file/dir
--copy-unsafe-links	only "unsafe" symlinks are transformed
--safe-links	ignore symlinks that point outside the source tree
-k, --copy-dirlinks	transform symlink to a dir into referent dir
-K, --keep-dirlinks	treat symlinked dir on receiver as dir
-H, --hard-links	preserve hard links
-p, --perms	preserve permissions
-E, --executability	preserve the file's executability
--chmod=CHMOD	affect file and/or directory permissions
-A, --acls	preserve ACLs (implies --perms)
-X, --xattrs	preserve extended attributes
-o, --owner	preserve owner (super-user only)
-g, --group	preserve group
--devices	preserve device files (super-user only)
--copy-devices	copy device contents as regular file
--specials	preserve special files
-D	same as --devices --specials
-t, --times	preserve modification times
-O, --omit-dir-times	omit directories from --times
--super	receiver attempts super-user activities
--fake-super	store/recover privileged attrs using xattrs
-S, --sparse	handle sparse files efficiently
-n, --dry-run	perform a trial run with no changes made
-W, --whole-file	copy files whole (without delta-xfer algorithm)
-x, --one-file-system	don't cross filesystem boundaries
-B, --block-size=SIZE	force a fixed checksum block-size
-e, --rsh=COMMAND	specify the remote shell to use
--rsync-path=PROGRAM	specify the rsync to run on the remote machine
--existing	skip creating new files on receiver
--ignore-existing	skip updating files that already exist on receiver
--remove-source-files	sender removes synchronized files (non-dirs)
--del	an alias for --delete-during
--delete	delete extraneous files from destination dirs
--delete-before	receiver deletes before transfer, not during
--delete-during	receiver deletes during the transfer
--delete-delay	find deletions during, delete after
--delete-after	receiver deletes after transfer, not during
--delete-excluded	also delete excluded files from destination dirs
--ignore-errors	delete even if there are I/O errors
--force	force deletion of directories even if not empty
--max-delete=NUM	don't delete more than NUM files
--max-size=SIZE	don't transfer any file larger than SIZE
--min-size=SIZE	don't transfer any file smaller than SIZE
--partial	keep partially transferred files
--partial-dir=DIR	put a partially transferred file into DIR
--delay-updates	put all updated files into place at transfer's end
-m, --prune-empty-dirs	prune empty directory chains from the file-list
--numeric-ids	don't map uid/gid values by user/group name
--timeout=SECONDS	set I/O timeout in seconds
--contimeout=SECONDS	set daemon connection timeout in seconds
-I, --ignore-times	don't skip files that match in size and mod-time
--size-only	skip files that match in size
--modify-window=NUM	compare mod-times with reduced accuracy
-T, --temp-dir=DIR	create temporary files in directory DIR
-y, --fuzzy	find similar file for basis if no dest file
--compare-dest=DIR	also compare destination files relative to DIR
--copy-dest=DIR	... and include copies of unchanged files
--link-dest=DIR	hardlink to files in DIR when unchanged
-z, --compress	compress file data during the transfer
--compress-level=NUM	explicitly set compression level
--skip-compress=LIST	skip compressing files with a suffix in LIST
-C, --cvs-exclude	auto-ignore files the same way CVS does
-f, --filter=RULE	add a file-filtering RULE
-F	same as --filter='dir-merge /.rsync-filter'
	repeated: --filter='- .rsync-filter'
--exclude=PATTERN	exclude files matching PATTERN
--exclude-from=FILE	read exclude patterns from FILE
--include=PATTERN	don't exclude files matching PATTERN
--include-from=FILE	read include patterns from FILE
--files-from=FILE	read list of source-file names from FILE
-0, --from0	all *-from/filter files are delimited by 0s
-s, --protect-args	no space-splitting; only wildcard special-chars
--address=ADDRESS	bind address for outgoing socket to daemon
--port=PORT	specify double-colon alternate port number
--sockopts=OPTIONS	specify custom TCP options
--blocking-io	use blocking I/O for the remote shell
--stats	give some file-transfer stats
-8, --8-bit-output	leave high-bit chars unescaped in output
-h, --human-readable	output numbers in a human-readable format
--progress	show progress during transfer
-P	same as --partial --progress
-i, --itemize-changes	output a change-summary for all updates
--out-format=FORMAT	output updates using the specified FORMAT
--log-file=FILE	log what we're doing to the specified FILE
--log-file-format=FMT	log updates using the specified FMT
--password-file=FILE	read daemon-access password from FILE
--list-only	list the files instead of copying them
--bwlimit=KBPS	limit I/O bandwidth; KBytes per second
--write-batch=FILE	write a batched update to FILE
--only-write-batch=FILE	like --write-batch but w/o updating destination
--read-batch=FILE	read a batched update from FILE
--protocol=NUM	force an older protocol version to be used
--iconv=CONVERT_SPEC	request charset conversion of filenames
--checksum-seed=NUM	set block/file checksum seed (advanced)
-4, --ipv4	prefer IPv4
-6, --ipv6	prefer IPv6
--version	print version number
(-h) --help	show this help (-h is --help only if used alone)

10 Practical Examples of Rsync Command in Linux

Remote Sync is a most commonly used command for copying and synchronizing files and directories remotely as well as locally in Linux systems. With the help of rsync command you can copy and synchronize your data remotely and locally across directories, across disks and networks, perform data backups and mirroring between two Linux machines.

You don’t need to be root user to run rsync command.

Advantages and features of Rsync
It efficiently copies and sync files to or from a remote system.
Supports copying links, devices, owners, groups and permissions.
It’s faster than scp (Secure Copy) because rsync uses remote-update protocol which allows to transfer just the differences between two sets of files. First time, it copies the whole content of a file or a directory from source to destination but from next time, it copies only the changed blocks and bytes to the destination.
Rsync consumes less bandwidth as it uses compression and decompression method while sending and receiving data both ends

We can install rsync package with the help of following command.

# yum install rsync (On Red Hat based systems)
# apt-get install rsync (On Debian based systems)



Basic syntax of rsync command

# rsync  <options>  <source>  <destination>

rsync commands options
-v : verbose
-r : copies data recursively (but don’t preserve timestamps and permission while transferring data
-a : archive mode, archive mode allows copying files recursively and it also preserves symbolic links, file permissions, user & group ownerships and timestamps
-z : compress file data
-h : human-readable, output numbers in a human-readable format

========================================================
1. Copy/Sync Files and Directory Locally

This following command will sync a single file on a local machine from one location to another location.
Example, a file name test.log.1.gz needs to be copied or synced to /tmp/data_backup/ folder.
---------------------------------------------------------
[root@localhost mnt]# rsync -zvh    test.log.1.gz     /tmp/data_backup/
created directory /tmp/data_backup
test.log.1.gz

sent 1.35K bytes  received 31 bytes  2.77K bytes/sec
total size is 1.27K  speedup is 0.92
---------------------------------------------------------
In above example, you can see that if the destination is not already exists rsync will create a directory automatically for destination
========================================================
The following command will transfer or sync all the files of from one directory to a different directory in the same machine

1.1 Copy/Sync Files and Directory Locally
---------------------------------------------------------
[root@localhost mnt]# rsync -avzh test/ /tmp/data_backup/
sending incremental file list
./
test.log.1.gz
test.log.2.gz
test.log.3.gz

sent 4.04K bytes  received 72 bytes  2.74K bytes/sec
total size is 3.82K  speedup is 0.93
========================================================
2. Copy/Sync Files and Directory to or From a Server

This command will sync a directory from a local machine to a remote machine.
---------------------------------------------------------
[root@localhost]$ rsync -avz test/ root@192.168.10.11:/home/
root@192.168.10.11's password:
sending incremental file list
./
test.log.1.gz
test.log.2.gz
test.log.3.gz
sent 4993369 bytes  received 91 bytes  399476.80 bytes/sec
total size is 4991313  speedup is 1.00
========================================================
2.1 Copy/Sync a Remote Directory to a Local Machine

This command will help you sync a remote directory to a local directory
---------------------------------------------------------
[root@tecmint]# rsync -avzh root@192.168.10.11:/home/test /tmp/backup/
root@192.168.10.11's password:
receiving incremental file list
created directory /tmp/backup
test.log.1.gz
test.log.2.gz
test.log.3.gz
sent 91 bytes  received 4.99M bytes  322.16K bytes/sec
total size is 4.99M  speedup is 1.00
========================================================
3. Rsync Over SSH   

Copy a File from a Remote Server to a Local Server with SSH

To specify a protocol with rsync you need to give “-e” option with protocol name you want to use.
Here in this example, We will be using “ssh” with “-e” option and perform data transfer.

[root@localhost]# rsync -avzhe ssh root@192.168.10.11:/var/log/mgimx/access.log /tmp/
========================================================
3.1 Copy a File from a Local Server to a Remote Server with SSH

[root@localhost]# rsync -avzhe ssh backup.tar root@192.168.10.11:/tmp/backups/
========================================================
4. Show Progress While Transferring Data with rsync

[root@localhost]# rsync -avzhe ssh --progress /home/demo.test root@192.168.0.100:/root/demo.test
root@192.168.0.100's password:
sending incremental file list
created directory /root/demo.test
demo.test/
demo.test/httpd-2.2.3-82.el5.centos.i386.rpm
1.02M 100%        2.72MB/s        0:00:00 (xfer#1, to-check=3/5)
demo.test/mod_ssl-2.2.3-82.el5.centos.i386.rpm
99.04K 100%  241.19kB/s        0:00:00 (xfer#2, to-check=2/5)
demo.test/nagios-3.5.0.tar.gz
1.79M 100%        1.56MB/s        0:00:01 (xfer#3, to-check=1/5)
demo.test/nagios-plugins-1.4.16.tar.gz
2.09M 100%        1.47MB/s        0:00:01 (xfer#4, to-check=0/5)
sent 4.99M bytes  received 92 bytes  475.56K bytes/sec
total size is 4.99M  speedup is 1.00
========================================================
5. Use of –include and –exclude Options

These two options allows us to include and exclude files by specifying parameters
with these option helps us to specify those files or directories which you want to
include in your sync and exclude files and folders with you don’t want to be transferred.

Here in this example, rsync command will include those files and directory only which
starts with ‘php’ and exclude all other files and directory.

[root@localhost]# rsync -avze ssh --include 'php*' --exclude '*' root@192.168.0.101:/var/www/html/ /tem/demo
========================================================
6. Use of –delete Option

If a file or directory not exist at the source, but already exists at the destination,
you might want to delete that existing file/directory at the target while syncing.

We can use ‘–delete‘ option to delete files that are not there in source directory.

Source and target are in sync. Now creating new file test.txt at the target.
-------------------------------------------------------------
[root@localhost]# touch test.txt
[root@localhost]# rsync -avz --delete root@192.168.10.11:/var/www/html/  .
Password:
receiving file list ... done
deleting test.txt
./
sent 26 bytes  received 390 bytes  48.94 bytes/sec
total size is 45305958  speedup is 108908.55
 ----------------------------------------------------------

Target has the new file called test.txt, when synchronize with the source with ‘–delete‘ option, it removed the file test.txt.
 ========================================================
7. Set the Max Size of Files to be Transferred
You can specify the Max file size to be transferred or sync.
You can do it with “–max-size” option. Here in this example,
ax file size is 200k, so this command will transfer only those files which are equal or smaller than 200k.

[root@localhost]# rsync -avzhe ssh --max-size='200k' /var/www/html/ root@192.168.0.100:/tmp/backup 
========================================================

8. Automatically Delete source Files after successful Transfer
Now, suppose you have a main web server and a data backup server,
you created a daily backup and synced it with your backup server,
now you don’t want to keep that local copy of backup in your web server.

So, will you wait for transfer to complete and then delete those local backup
file manually? Of Course NO. This automatic deletion can be done using ‘–remove-source-files‘ option.

[root@localhost]# rsync --remove-source-files -zvh backup.tar /tmp/backups/
backup.tar
sent 14.71M bytes  received 31 bytes  4.20M bytes/sec
total size is 16.18M  speedup is 1.10
[root@tecmint]# ll backup.tar
ls: backup.tar: No such file or directory

========================================================
9. Do a Dry Run with rsync
If you are a newbie and using rsync and don’t know what exactly your command going do.
Rsync could really mess up the things in your destination folder and then doing an undo can be a tedious job.

Use of this option will not make any changes only do a dry run of the command and shows the
output of the command, if the output shows exactly same you want to do then you can
remove ‘–dry-run‘ option from your command and run on the terminal.

root@localhost]# rsync --dry-run --remove-source-files -zvh backup.tar /tmp/backups/
backup.tar
sent 35 bytes  received 15 bytes  100.00 bytes/sec
total size is 16.18M  speedup is 323584.00 (DRY RUN)

========================================================
10. Set Bandwidth Limit and Transfer File
You can set the bandwidth limit while transferring data from one machine to another machine with the the help of ‘–bwlimit‘ option. This options helps us to limit I/O bandwidth.
----------------------------------------------------------
[root@localhost]# rsync --bwlimit=100 -avzhe ssh  /var/www/html/  root@192.168.0.100:/tmp/backups/
root@192.168.10.11's password:
sending incremental file list
sent 324 bytes  received 12 bytes  61.09 bytes/sec
total size is 38.08M  speedup is 113347.05
----------------------------------------------------------
Also, by default rsync syncs changed blocks and bytes only, if you want explicitly want to sync whole file then you use ‘-W‘ option with it.
----------------------------------------------------------
[root@localhost]# rsync -zvhW backup.tar /tmp/backups/backup.tar
backup.tar
sent 14.71M bytes  received 31 bytes  3.27M bytes/sec
total size is 16.18M  speedup is 1.10
 =====================================================
 How to Sync Two Apache Web Servers/Websites Using Rsync
 =====================================================
How to Use Rsync to Sync New or Changed/Modified Files in Linux 
 =====================================================

SYSTEM ADMINISTRATOR TASK - INTERVIEW QUESATIONS

.................     TASKS  .........
01. Try different types of editor (pico, nano, vi, vim, mc, emac)
02. Set e2fsck 0 and e2fsck 2 and reboot the system
03. Reinstall “/” format but do not format other partitions
04. Extend swap 2 way (1 partition way, 2 file way using dd command)
05. Convert script to binary format
06. ps 15 examples
07. netstat 15 examples
08. tcpdump tool 5 examples
09. rsync command 15 examples
10. Find command 15 examples
11. Create 1 ubuntu 1 vm and try to use
12. CentOs 7 1 Vm and try to use
13. grep 15 examples
14. Try to view initrd.img
15. 2 partition 1 mount point and 1 partition 2 mount point
16. Install rdesktop via (source code download from internet)
17. Create LVM snapshot + (techmint website)
18. Go to rescue mode and reduce ‘/’ Partition
19. Try yum priority plugin
20. Configure local repo for yum
21. tune2fs 10 flags
22. Run job in sec in crond
23. kernel compilation and (ntfs enable & sound disable)
24. Implement sftp Server
25. vi sudo configure use sudoers
26. dd cmd 15 examples
27. top 5 flags examples
28. vmstat 10 examples
29. mpstat 10 examples
30. sar 10 examples
31. iostat 10 examples
32. Try capture network packages using tcpdump & wireshark
33. Set a path and umask for specific user
34. Where history and cd command located
35. rm –rf /bin/bash
36. To view MBR use ‘od’ command
37. Change MAC ID and try access
38. Persist IP aliasing
39. Create any user without using useradd command
40. Hiren boot cd
41. Try skip and reboot in rescue mode
42. How to make SSH password less
43. Try samba 4
44. How to clone HDD to HDD
45. Make your system in readonly mode
46. Give 5 interview ( Fail )
47. Try to install all partition ( 5 times )
48. Installation “ / “ in single partition ( 5 times )
49. Try to do installation in minimal / text based way ( 5 times )
50. Create ISO file from DVD using magic ISO
51. Copy the history in Pen drive
52. How to do data pre append in beginning
53. Use the multiple zip command on single file ( gzip & bzip2 )
54. Try rm –rf /*
55. Try to switch different run level
56. Try schedule shutdown & use all flags of shutdown
57. How to switch safe mode in windows boot ( press fn8 )
58. Go to single user mode and change root password
59. Change the default run level to 3
60. Go to inittab file and change the default run level to 6 and solve the reboot issue
61. How to secure the single user mode
62. Try logout from root and login new user using switch user command
63. Try to change permission of file by using chmod command ( u , g , o )
64. Create a file test in /usr/local
Condition
1. Joe user should be able to rwx
2. Rahul , Sachin and Ramu users should be able to r-x
3. Harry user able to rwx
4. Shamu and other users should be able to read only
65. Install VMware tools
66. Create 4 partition 100MB, 50MB, 200MB, 150MB
1. Second partition should be extended
2. Mount first 2 partition on / part1, /part2 respectively
3. 3rd and 4th partition on /usr/local/part3 and /usr/local/part4
67. Create 3 partitions using parted tool
68. Convert msdos/mbr to gpt and vice versa
69. Make the 4 partition and delete it
70. Take a snapshot and delete the fstab file and check the error
71. Move all commands to opt directory and test all the commands
72. Try rm –rf /lib/libc.so.6 and check the error
73. Format only “ / “ partition and reinstall it
74. Find the 5 flags of dmidecode & biosdecode
75. Rename the inittab file and check the error
76. Go to /etc/rc.sysinit and change the hostname
77. Change OK to HOI and FAILED to NAPASS in boot process
78. Change OK color green to yellow in boot process
79. Video recording of boot process
80. NFS service start in run level 3 and should not start in run level 5
81. Go to /etc/redhat-release file and change welcome screen name
82. How to exclude in rm –rf
83. Write power off /etc/rc.local and see what happened
84. Go to /etc/rc0.d file and change halt to reboot and
In /etc/rc6.d file change reboot to halt
85. With the help of nc command we can chat peer to peer chatting
86. Run winamp with win tool in Linux
87. How lvm migration
88. Try lvm stripping
89. Add additional repository under yum
90. Write all in /etc/hosts.allow and /etc/hosts.deny and check the what happened
91. Delete all the partition and see the error and resolve it by using testdisk tool
92. How to remove first stage of boot process
93. How to set suid , sgid , sticky bit and setfacl do practice
94. Change splash screen image
95. Try awk sort grep trap exit, gawk cut egrep break sed
96. Change directory color to yellow and file color to white
97. How to fast boot using splash screen
98. Make Linux non case sensitive
99. When a user logout you should receive a mail