Basic Linux commands

lsLists all files and directories in the present working directory
ls-RLists files in sub-directories as well
ls-aLists hidden files as well
ls-alLists files and directories with detailed information like permissions,size, owner, etc.
cd or cd ~Navigate to HOME directory
cd ..Move one level up
cdTo change to a particular directory
cd /Move to the root directory
cat > filenameCreates a new file
cat filenameDisplays the file content
cat file1 file2 > file3Joins two files (file1, file2) and stores the output in a new file (file3)
mv file “new file path”Moves the files to the new location
mv filename new_file_nameRenames the file to a new filename
sudoAllows regular users to run programs with the security privileges of the superuser or root
rm filenameDeletes a file
manGives help information on a command
historyGives a list of all past commands typed in the current terminal session
clearClears the terminal
mkdir directorynameCreates a new directory in the present working directory or a at the specified path
rmdirDeletes a directory
mvRenames a directory
pr -xDivides the file into x columns
pr -hAssigns a header to the file
pr -nDenotes the file with Line Numbers
lp -nc , lpr cPrints “c” copies of the File
lp-d lp-PSpecifies name of the printer
apt-getCommand used to install and update packages
mail -s ‘subject’ -c ‘cc-address’ -b ‘bcc-address’ ‘to-address’Command to send email
mail -s “Subject” to-address < FilenameCommand to send email with attachment

File Permission commands

ls-lto show file type and access permission
rread permission
wwrite permission
xexecute permission
-=no permission
Chown userFor changing the ownership of a file/directory
Chown user:group filenamechange the user as well as group for a file or directory

Environment Variables command

echo $VARIABLETo display value of a variable
envDisplays all environment variables
VARIABLE_NAME= variable_valueCreate a new variable
UnsetRemove a variable
export Variable=valueTo set value of an environment variable

User management commands of linux

sudo adduser usernameTo add a new user
sudo passwd -l ‘username’To change the password of a user
sudo userdel -r ‘username’To remove a newly created user
sudo usermod -a -G GROUPNAME USERNAMETo add a user to a group
sudo deluser USER GROUPNAMETo remove a user from a group
fingerShows information of all the users logged in
finger usernameGives information of a particular user

Networking command

SSH username@ip-address or hostnamelogin into a remote Linux machine using SSH
Ping hostname=”” or =””To ping and Analyzing network and host connections
dirDisplay files in the current directory of a remote computer
cd “dirname”change directory to “dirname” on a remote computer
put fileupload ‘file’ from local to remote computer
get fileDownload ‘file’ from remote to local computer

Process command

bgTo send a process to the background
fgTo run a stopped process in the foreground
topDetails on all Active Processes
psGive the status of processes running for a user
ps PIDGives the status of a particular process
pidofGives the Process ID (PID) of a process
kill PIDKills a process
niceStarts a process with a given priority
reniceChanges priority of an already running process
dfGives free hard disk space on your system
freeGives free RAM on your system

VI Editing Commands

iInsert at cursor (goes into insert mode)
aWrite after cursor (goes into insert mode)
AWrite at the end of line (goes into insert mode)
ESCTerminate insert mode
uUndo last change
UUndo all changes to the entire line
oOpen a new line (goes into insert mode)
ddDelete line
3ddDelete 3 lines
DDelete contents of line after the cursor
CDelete contents of a line after the cursor and insert new text. Press ESC key to end insertion.
dwDelete word
4dwDelete 4 words
cwChange word
xDelete character at the cursor
rReplace character
ROverwrite characters from cursor onward
sSubstitute one character under cursor continue to insert
SSubstitute entire line and begin to insert at the beginning of the line
~Change case of individual character