Linux

Linux Commands

command	Description
mkdir	Create a new directory with given name
ls	List the content in the directory
cd	Change to directory
touch	Create empty files
cat > fileName	Create a new file & write content into file “& Ctrl+D to save
cat fileName	Display content of a file
cat file1 file2 file 3	Copy 2 file and write it into a new file
pwd	Current working directory
cp	Copy a file into a new file. cp file3.txt file4.txt
mv	Moves a file/directory
head	The top ten lines of a file. sudo head vamsi.txt
tail	Get last 10 lines of a file
tae	Reverse order of contents of a file
more	Similar to cat, we can display large content by using Enter
id	Display id of user /group
vi	Text editor
grep	Search pattern
diff	This command is used to display the differences in the files by comparing the files line by line.
ping	Status of server
history	Review all commands
hostname	To know the host name of the server
hostname -i	Ip address
ch mod	Change the user/group permission to access files ch mod u =r file2.txt
nl	Display the line numbers
wc	No. of lines ,words ,characters
uniq	Remove duplicates of file content
It will remove only continuous duplicates.
rmdir	Remove the specified directory if the directory is empty
Rm	Remove file/directory.
chown	Assign directory/file to a specific user

User Creation in Linux:

To create user groups: sudo groupadd groupName

sudo useradd username

sudo passwd password

To get all users list cat /etc/passwd

To Delete a user: sudo userdel -r username

To delete group: sudo groupdel groupName

Mapping a user to a group: sudo usermod -a -G groupName username

File Permissions:

1.Read (r) 2.Write(w) 3.Execute (x)

3 Roles- Owner, Group, Others

ll -> command to know the permissions of file/folders in the root

ls -l -> to know the file /folder permissions in the current directory

drwx r-x user, group, others, d -> type of file