ServerServer, it is just a machine(host/guest vm) which is configured with some services or running instances of an application (software) capable of accepting requests from the client and giving responses accordingly.

We use Linux serversLinux is a kernel, on which basis there are number of OS flavours are avaiilable

● Ubuntu● RedHat● CentOS● Debian & etc

Principle of linux1. Everything is a file :2. Configuration data of the system is stored in text usually named with extension, .conf3. Connection pipes for standard I/O to chain programs

echo $SHELL

/bin/bash

chsh

1. /etc/group File – Group Information:Holds 4 information delimited by colon(:) in the following format.

group_name:x:group_id:users

2. /etc/passwd File – User Information:It holds 7 information delimited by colon(:).

user_login:x:user_id:user_primary_group_id:comment_or_user_name:home_directory_path:default_login_shell

3. /etc/shadow File – User Login Information:• User name : It is your login name.• Password: It your encrypted password. The password should be minimum 6-8 characters long including special characters/digits• Last password change (lastchanged): Days since Jan 1, 1970 that password was last changed.• Minimum: The minimum number of days required between password changes i.e. the number of days left before the user is

allowed to change his/her password.• Maximum: The maximum number of days the password is valid (after that user is forced to change his/her password).• Warn : The number of days before password is to expire that user is warned that his/her password must be changed.• Inactive : The number of days after password expires that account is disabled.• Expire : days since Jan 1, 1970 that account is disabled i.e. an absolute date specifying when the login may no longer be used.

● A system user is intended to be used by programs (applications).● A normal user is intended to be used by people (like you and me).

Syntax:# useradd options user_name

Syntax:# useradd -D

Syntax :# useradd -u 106 -g 508 -c “This is a linux group” -d /home/vivek -s /bin/bash vivek

Syntax:# usermod -s /bin/sh vivek

Syntax:# userdel vivek

Command Group-Id Home Directory

ShellCommentUser_id

UserName

Syntax:# groupadd options group_name

-F : If the group is already available then it should display.-g : Group ID is supplied by this actions.-o : giving ID which is not unique-r : Add to system account.

Syntax:# groupdelete group_name

Syntax:# passwd

Output:Changing password for test.(current) UNIX password: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully

Syntax:# pwd

Syntax:# cd

Syntax:# ls options arguments

Command Result

ls List the files in the working directory

ls /bin List the files in the /bin directory (or any other directory you care to specify)

ls -l List the files in the working directory in long format

ls -l /etc /bin

List the files in the /bin directory and the /etc directory in long format

ls -la .. List all files (even ones with names beginning with a period character, which are normally hidden) in the parent of the working directory in long format

O/P $ pwd/Users/vivek

viveks-MacBook-Pro:~ vivek$ cd /usr/X11R6viveks-MacBook-Pro:X11R6 vivek$ pwd/usr/X11R6

The "." symbol refers to the working directory and the ".." symbol refers to the working directory's parent directory.

viveks-MacBook-Pro:~ vivek$ ls -la

-rw------- 1 root wheel 576 Apr 17 1998 vivek.txtdrwxr-xr-x 6 root wheel 1024 Oct 9 1999 Projects-rw-rw-r-- 1 root wheel 276480 Feb 11 20:41 vivek.sql-rw------- 1 root wheel 5743 Dec 16 1998 .Xauthority---------- ------- ------- -------- ------------ ------------- | | | | | | | | | | | File Name | | | | | | | | | +--- Modification Time | | | | | | | +------------- Size (in bytes) | | | | | +----------------------- Group | | | +-------------------------------- Owner | +---------------------------------------------- File Permissions

Syntax:# less file_name

Syntax:# find path pattern

Syntax:# find . -name foo

Syntax:# locate pattern

Syntax:# locate finger

Syntax:# which command

Syntax:# which gedit

/usr/bin/gedit

Syntax:# whereis command

Syntax:# whereis find

/usr/bin/find /usr/share/man/man1p/find.1p.gz /usr/share/man/man1/find.1.gz

The above command searches through the current working directory for all files with "foo" in their name.

The search results could include a file called finger.txt, a file called pointerfinger.txt, a directory named /fingerthumbnails/, and so on. To learn more about locate, read the locate man page.

which returns the location of binary, or executable, shell commands. The information provided by which is useful for creating application launchers.

The following command returns the locations of: the binary of find, the location of the source code, and the location of the find man page.

Syntax:# cp [options] source dest

Syntax:# mv [options] source destination

viveks:~ vivek$ cp -u *.html /testonly copy all the HTML files that did not exist in the test directory or were newer than the versions in the destination directory

Syntax:# rm [options] file_name/directory_name

Syntax:# mkdir diectory

Syntax:# touch [options] file_name

Syntax:# cat [options] file_name

Syntax:# cat > file_name

Syntax:# cat >> file_name

Syntax:# cat -n file_name

Syntax:# sort filename

$ ls -lt | sort -n -k 5

-rw-r--r-- 1 vivek vivek 0 2012-12-03 00:09 1sampleFile.txt

total 44

-rw-r--r-- 1 vivek vivek 6 2012-12-03 01:03 file

-rw-r--r-- 1 vivek vivek 6 2012-12-03 01:04 file2

-rw-r--r-- 1 vivek vivek 6 2012-12-03 01:10 sfile

-rw-r--r-- 1 vivek rupali 15 2012-12-03 01:12 strfile2

-rw-r--r-- 1 vivek vivek 21 2012-12-03 01:13 strfile

Syntax:# wc [options] file_name

wc -l : Prints the number of lines in a file.wc -w : prints the number of words in a file.wc -c : Displays the count of bytes in a file.wc -m : prints the count of characters from a file.wc -L : prints only the length of the longest line in a file.

viveks:~ vivek$ ls -l /bin/bash

-rwxr-xr-x 1 root root 316848 Feb 27 2013 /bin/bash

●●●●●

Syntax:# chmod 600 some_file

Syntax:# su

Syntax:# chown [OPTION] [OWNER][:[GROUP]] FILE

Syntax:# chown -r vivek:staff /home/vivek/projects

Syntax:# ps

PID PPID PGID TTY UID STIME COMMAND

2152 1 2152 con 1000 13:19:07 /usr/bin/bash

2276 2152 2276 con 1000 14:53:48 /usr/bin/ps

$ ./analyze results*.dat

...a few minutes pass...

^C

$ ./analyze results*.dat &

[1] 6891

$ jobs

[1] ./analyze results01.dat results02.dat results03.dat

$ fg

Show background processes

Bring background job to foregroundUse fg %1, fg %2, etc. if there are

several background jobs

$ ./analyze results01.dat

^Z

[1] Stopped ./analyze results01.dat

$ bg %1

$ sleep 120; echo “I am awake.”

$ kill %1

[1]+ Terminated ./analyze results01.dat

$ kill pid

$ killall ./analyze

$ killall -9 ./analyze

$ nohup ./analyze results01.dat &

Stand

Syntax:# > MyFile.txt

MyFile

Syntax:# ls > MyFile.txt

Syntax:# sort > MyFile.txt

Syntax:# command 1>output_file 2>error_file

Syntax:#

Syntax:# Syntax:# command >&output_file

Syntax:# ls -lR >everything 2>/dev/null

Syntax:# cat MyFile.txt | sort | lpr

PIPE

PIPE

><>>2>

Redirect the output of a command, input to a command, or diagnostic

output into some file or I/O device.

|Redirect the output of a command to

become the input to anothercommand.

Program What it does

sort Sorts standard input then outputs the sorted result on standard output.

uniq Given a sorted stream of data from standard input, it removes duplicate lines of data (i.e., it makes sure that every line is unique).

grep Examines each line of data it receives from standard input and outputs every line that contains a specified pattern of characters.

head Outputs the first few lines of its input. Useful for getting the header of a file.

tail Outputs the last few lines of its input. Useful for things like getting the most recent entries from a log file.

sed Stream editor. Can perform more sophisticated text translations than tr.

awk An entire programming language designed for constructing filters. Extremely powerful.

Compressing/Uncompress file or directoriestargzipzip

Copy/Transfer file or directory to remote serverrsyncscp

Syntax:# bzip2 MyFile.txt

Syntax:# bunzip2 MyFile.txt.bz2

Compression Tool File Extension Decompression Tool

bzip2 .bz2 bunzip2

gzip .gz gunzip

zip .zip unzip

Syntax:# gzip MyFile.txt

Syntax:# gunzip MyFile.txt.gz

Syntax:# gzip -r MyFile.gz file1 file2 file3 /home/vivek/work

Syntax:# zip MyFile.txt

Syntax:# gunzip MyFile.txt.zip

●●

●●●●●

Syntax:# tar -cvf filename.tar directory/file

Syntax:# tar -tvf filename.tar directory/file

Syntax:# tar -tvf filename.tar directory/file

Syntax:# tar -czvf filename.tgz file

Compressing Files

Syntax Description Example(s)

gzip {filename}

Gzip compress the size of the given files using Lempel-Ziv coding (LZ77). Whenever possible, each file is replaced by one with the extension .gz.

gzip mydata.docgzip *.jpgls -l

bzip2 {filename}

bzip2 compresses files using the Burrows-Wheeler block sorting text compression algorithm, and Huffman coding. Compression is generally considerably better than that achieved by bzip command (LZ77/LZ78-based compressors). Whenever possible, each file is replaced by one with the extension .bz2.

bzip2 mydata.docbzip2 *.jpgls -l

zip {.zip-filename} {filename-to-compress}

zip is a compression and file packaging utility for Unix/Linux. Each file is stored in single .zip {.zip-filename} file with the extension .zip.

zip mydata.zip mydata.doczip data.zip *.docls -l

tar -zcvf {.tgz-file} {files}tar -jcvf {.tbz2-file} {files}

The GNU tar is archiving utility but it can be use to compressing large file(s). GNU tar supports both archive compressing through gzip and bzip2. If you have more than 2 files then it is recommended to use tar instead of gzip or bzip2.-z: use gzip compress-j: use bzip2 compress

tar -zcvf data.tgz *.doctar -zcvf pics.tar.gz *.jpg *.pngtar -jcvf data.tbz2 *.docls -l

Syntax Description Example(s)

gzip -l {.gz file} List files from a GZIP archive gzip -l mydata.doc.gz

unzip -l {.zip file} List files from a ZIP archive unzip -l mydata.zip

tar -ztvf {.tar.gz}tar -jtvf {.tbz2}

List files from a TAR archive tar -ztvf pics.tar.gztar -jtvf data.tbz2

Syntax Description Example(s)

gzip -d {.gz file}gunzip {.gz file}

Decompressed a file that is created using gzip command. File is restored to their original form using this command.

gzip -d mydata.doc.gzgunzip mydata.doc.gz

bzip2 -d {.bz2-file}bunzip2 {.bz2-file}

Decompressed a file that is created using bzip2 command. File is restored to their original form using this command.

bzip2 -d mydata.doc.bz2gunzip mydata.doc.bz2

unzip {.zip file} Extract compressed files in a ZIP archive.

unzip file.zipunzip data.zip resume.doc

tar -zxvf {.tgz-file}tar -jxvf {.tbz2-file}

Untar or decompressed a file(s) that is created using tar compressing through gzip and bzip2 filter

tar -zxvf data.tgz tar -zxvf pics.tar.gz *.jpgtar -jxvf data.tbz2

Syntax:# vmstat 3

Display Memory Utilization SlabinfoSyntax:# vmstat -m

Get Information About Active / Inactive Memory PagesSyntax:# vmstat -a

Syntax:# w user_name

Syntax:# w vivek

Syntax:# uptime

18:02:41 up 41 days, 23:42, 1 user, load average: 0.00, 0.00, 0.00

Syntax:# uptime

Cloud and Servers

Webserver A web server is a computer system that processes requests via HTTP, In sinpme word - The basic network protocol used to distribute information on the World Wide Web.

We use - Apache & NginxApache The Apache HTTP Server Project is an effort to develop and maintain an open-source HTTP server for modern operating systems including UNIX and Windows NT

Rails App - Load PassengerPHP App - Load PHP modulePython APP - Load PYthon FCGI Module

NginxNginx (pronounced engine-x) is a free, open-source, high-performance HTTP server and reverse proxy, Nginx dosen’t include any module to interpret server side script. Always need to configure a service to interpret server side scripting.

Rails App - Unicorn, passengerPHP App - PHP-FPM, PHP-FastCGIPython App - WSCGI

Sample Vhost Configuration

<VirtualHost *:80>DocumentRoot /var/www/example1

ServerName www.example.com

# Other directives here

</VirtualHost>

server {listen 80;server_name www.example.com;

root /var/www/example.com;

index index.html index.htm;

# Other directives here}

Server Security

Its a terminology which defines the machine connected to internet & stands to server some kind of request that should be secured. Securing server also knowns as a server hardening

In a simple word● No access to unauthorized user● Secure from hacker attacks● Apply security & PCI compliance policies● Secure app from sql injection attacks● Use secure protocol if sending confidential data over the network● Apply firewall rules.

In basic practices, follow the below mentioned rules in given manner.Firewall rules(iptables in linux), UFW, Fail2banSelinux (If exist)Secure server at service levelSpecial permissions (ACL)Simple permission/ User level permissions

Log Management

Log management (LM) comprises an approach to dealing with large volumes of computer generated log messages. To ensure rotate unwanted logs file to avoid unwanted disk space consumption.

There are two approaches for log managementRotate logs on the local system(on the same machine)rsync the computer generated log to some other location/Server.

Some time these issues create critical situations like crashing servers, service not able to generate files, no disk space left but inode is free etc.Linux provides a service called logrotate. which helps to manage logs on local system. And rsyslog to transfer logs to remote server

In our practicesRotates the log file(App log, service logs, system logs etc) according to size, weekly rotation, daily rotation.Purging old log files which are no more needed.

Installing software on Linux involves package managers and software repositories or install from source code.Different flavour of linux based OS have its own package manager.

Debian,Ubuntu - apt-get or dpkgFedora, CentOS - yum, rpmOpensuse - Zypper

To list installed packages -: dpkg -l (ubuntu), rpm -qa (centOS)

To install package -: apt-get install <packagename>(ubuntu), yum install <packagename>(CentOS)

To remove packages -: apt-get remove/purge <packagename>(ubuntu), yum remove/purge <packagename>(CentOS)

Virtualization

Virtualization, in computing, refers to the act of creating a virtual (rather than actual) version of something, including but not limited to a virtual computer hardware platform, operating system (OS), storage device, or computer network resources.

Type of virtualization -:Full-VirtualizaTion

Almost complete simulation of the actual hardware to allow software, which typically consists of a guest operating system, to run unmodified.

Para-virtualizationA hardware environment is not simulated; however, the guest programs are executed in

theirown isolated domains, as if they are running on a separate system. Guest programs need to bespecifically modified to run in this environment.

Cloud

The practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer.

Cloud computing is computing in which large groups of remote servers are networked to allow the centralized data storage, and online access to computer services or resources. Clouds can be classified as public, private or hybrid.

Public Cloud - A cloud is called a "public cloud" when the services are rendered over a network that is open for public use. Public cloud services may be free or offered on a pay-per-usage model.

Private Cloud - Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party, and hosted either internally or externally.

Hybrid CLoud - Hybrid cloud is a composition of two or more clouds (private, community or public) that remain distinct entities but are bound together

Cloud Server A cloud server is a logical server that is built, hosted and delivered through a cloud computing platform over the Internet. Cloud servers possess and exhibit similar capabilities and functionality to a typical server but are accessed remotely from a cloud service provider.

Most used ones are -:AWS(Amazon Web Service)Rackspace cloudsometime other cloud provider

AWS S3 service Amazon S3 (Simple Storage Service) is an online file storage web service offered by Amazon Web Services. Amazon S3 provides storage through web services interfaces (REST, SOAP, and BitTorrent).

Block storageExtra block storage which can we create on-demand and attach it to the server instance

for additional state.

SnapshotThis is just clone of the server attached block storage, which is taken as a backup. From this

snapshot we can create new ebs from that.

Configuration management is a techniques to manage server/nodes from a central location/workstation. By which you can manage users, groups, packages & deployments rather than the files that manage those on each type of server you have.

Configuration management also store everything in a central place, which allows admins to quickly verify or change services across the network, automate their monitoring infrastructure, and gather data about the state and status of their network

I prefer to use chef Chef turns infrastructure into code. With Chef, you can automate how you build, deploy, and manage your infrastructure. From 6 months back, we are using chef to setup server infra.

Using forServer setupEnabling MonitoringEnabling securitySetup backups

Sharing static data between servers

Synchronize static data & data storage across the pool of real servers. Which is used bythe application to store data like images, audio etc.

Most use protocol is -:NFS server - The protocol which enabled file sharing between servers. S3 - AWS simple storage service which allow us to store data on cloud using REST, s3cmd etc

.

Thank You!