Play with Linux Commands.

Command to view what's written inside a file?

cat <filename>

The "cat" command shows the content written inside the file.

Example: Suppose, we have one file named "file1.txt" and inside this file "Hello DevOps" is written. So, to view what is written inside the file command should be like this

cat file1.txt

Command to change the access permission of a file?

chmod 777 file1.txt

The Above command gives all permissions i.e. read, write and execute permissions to all ( Users, Groups and Others ).

In the above screenshot, file1.txt has all the permission ( Read, Write, Execute )

Let's Understand how to provide permissions to a file in detail,

So, suppose you want to provide executable permission to groups, write permission to users and read permission to others, then the command should be like this,

executable permission to groups i.e. octal "1"

write permission to users i.e. octal "2"

read permission to others i.e. octal "4"

command: chmod 124 file1.txt

Command to check which commands you have run till now.

history

history command shows us what all commands we have you till now.

Command to remove Directory/Folder in Linux?

To remove an empty directory,

rmdir <directory-name>

To remove non-empty directories,

rm -r <directory-name>

Here, -r means recursively.

Command to create a fruits.txt file and to view the content?

To create a file "touch" command is used

touch <filename>

To view the content of a file, the "cat" command is used,

cat <filename>

Command to Add content in devops.txt (One in each line) - Apple, Mango, Banana, Cherry, Kiwi, Orange, Guava.

First create a file with "touch" command,

Example: touch devops.txt

Open devops.txt file with vim editor,

vim, nano editors are used to add content to a file.

Example: vim devops.txt

Press "i" to go into insert mode and add contents to the file,

and press "Esc + :wq" to save and exit from the file.

Command to show only top three fruits from the file?

head -3 <filename>

In the above command, the "head" command gives us first part of a file.

-3, --shows the top 3 lines of a file.

Command to Show only the bottom three fruits from the file.

tail -3 <filename>

In the above command, the "tail" command gives us last part of a file.

-3, --shows the bottom 3 lines of a file.

Command to create another file Colors.txt and to view the content.

touch <filename>

To see the content of a file,

cat <filename>

Command to add content in Colors.txt (One in each line) - Red, Pink, White, Black, Blue, Orange, Purple, Grey.

Open colors.txt file with vim editor,

vim, nano editors are used to add content to a file.

Example: vim colors.txt

Press "i" to go into insert mode and add contents to the file,

and press "Esc + :wq" to save and exit from the file.

Command to find the difference between fruits.txt and Colors.txt files.

diff <file1> <file2>

"diff" command is used to check difference between two files.

Let's understand with the help of the below screenshot,

Here, in "devops.txt" file we have content,

• Apple

• red

• blue

• yellow

• green

• maroon

• and in "colors.txt" file we have,

• red

• blue

• yellow

• green

• maroon

diff command shows the difference between two files