Basic Linux Commands Part2

Hi guys! In previous article, I described you about some basic commands and editors of Linux. If you are new to this series you can read that from below link-

Basic Linux Commands Part2

Most of us are well familiar with windows OS. Linux is also good platform. If you will start working on it, you will realize it.

Note : Most of the issues in Big Data came from Linux security section. I will try to cover it too. Today we will learn new topics under Linux basics. Be careful, Linux is case sensitive.

echo command:

                This is used to print some statements.

                Eg. user@machine:~$echo “This is sample statement by vimal”

We have few concepts for defining and saving standard input, output and error.

0 – for standard input

1 – for standard output

2 – for standard error

Please look into below image to understand it - 

Mail command:

To send a mail, we will use mail command.

user@machine:~$ mail –s”This is subject” user<messagebody.txt

grep command:

                grep is searching finding filtering tool. It can do things like pattern matching  & mapping

                eg. user@machine:~$ grep sometext file.txt

                       user@machine:~$ grep sometext ./*

                       user@machine:~$ grep sometext ./* | unique | cut –d: -f1

Pipes & Directional operators:

è user@machine:~$Program1 | Program2

§  This means output of program1 works as input for program2

§  Eg.

§  user@machine:~$ ps aux                             (to check processes)

§  user@machine:~$ ps aux | less | uniq | sort

è user@machine:~$Program1 && Program2

§  This means when program1 true then program2 execute

§  Eg.

§  user@machine:~$ ls filenotexist.txt && echo “Unsuccessful”

Package management with apt-get:

                apt-get mainly used for installation of softwares, packages

§  user@machine:~$ apt-get update

o   It may prompt permission denied. To avoid this we will use-

§  user@machine:~$ sudo apt-get update

§  user@machine:~$ sudo apt-get upgrade

§  user@machine:~$ sudo apt-get install  <applicationname>

o   To install any software or application

§  user@machine:~$ apt-cache search editor

o   To find editor

§  user@machine:~$ sudo apt-get remove  <applicationname>

o   To remove software or application

Basic Linux Commands Part1

Hi guys, I am writing series of article on Big Data. Industry mostly uses Linux or Unix for deploying their Big Data solution. So here I am covering some basics of Linux-

In Linux most of the work is done with command prompt, for this we use terminal. Other works are done with editors, it is same like notepad in windows.

Please find some useful commands and their use-

Sno.	Command Prompt	Command	Use
1	user@machine:~$	pwd	Print working directory
2	user@machine:~$	ls	List
3	user@machine:~$	ls -a	All listing
4	user@machine:~$	ls -al	All listing having permission to user
5	user@machine:~$	ls -alh	Human readable a long listing like 4 KB size
6	user@machine:~$	cd <directory>	Change directory
7	user@machine:~$	mkdir <dirname>	Make directory
8	user@machine:~$	mkdir -p <coolfolder/child/nested>	To create complete path
9	user@machine:~$	ls Desktop/Coolfolder<tab>	To get data
10	user@machine:~$	rm -r coolfolder	Remove recursive
11	user@machine:~$	rm -I coolfile.txt	To notify for remove
12	user@machine:~$	man <command>	Help or knowledge
13	user@machine:~$	touch <filename>	To create a file
14	user@machine:~$	mv tet.txt somefolder/	To move file
15	user@machine:~$	cp somefolder/text.txt /testcopy.txt	To copy
16	user@machine:~$	mv test.txt newName.txt	To rename
17	user@machine:~$	cd ..	Move up a dir
18	user@machine:~$	cd ../..	Move two up
19	user@machine:~$	cd <home/username>
20	user@machine:~$	cd ~	To home dir
21	user@machine:~$	cat <filename>	To read file
22	user@machine:~$	cat <filename1> <filename2>	To concat two files output

Editors :

1.      nano <filename>

                                                              i.      use ^X  (ctrl+X) to exit, it will prompt to save the file

                                                            ii.      ^W to search some data

2.      vi <filename>

                                                              i.      for creating files

                                                            ii.      for modifying & appending some text on already existing file

                                                          iii.      for displaying the content of file

                                                          iv.      use :wq to save and exit

                                                            v.      :q! to exit without save

Note : vi editior works on three modes

            Esc mode (Press Esc)

            Insert mode (Press i)

            Colon mode (press shift + ;)

3.      emacs <filename>

                                                              i.      Fast & mostly used by programmers

4.      vim <filename>

                                                              i.      Secure & mostly used by sysadmins

Cat command:

            This is one of the important command. It is mostly used for displaying the file contents, but it has so many other uses too.

o   cat>                 for creating files

o   cat>>               creating files if it is not exit or appending extra text if it is already exist

user@machine:~$ cat > file.txt

Write your content here

o   Press ctrl+d to save and exit

o   Press ctrl+c exiting file without saving

o   But you can’t change the content in previous line