40 Useful Linux commands for Everyone:
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➊ pwd
Print Working Directory
❯ pwd
# Shows the absolute path of
# the working directory
➋ mkdir
Make Directory
❯ mkdir reports/
# Creates a single directory
❯ mkdir -p reports/finance/yearly/
# Creates entire directory structure
➌ cd
Change Directory
❯ cd icons
# Switch to the “icons” directory
❯ cd –
# Switch to the previous directory
❯ cd ..
# Switch to the parent directory
❯ cd
# Switch to the home directory
➍ ls
List
❯ ls
# For current working directory
❯ ls /home/
# For /home/
❯ ls -a
# Includes hidden files
❯ ls -R
# Recursively for subdirectories
❯ ls -l
# Lists in detail
❯ ls -ltr
# Sorted. Latest modified one is at the top.
➎ cp
Copy
❯ cp file1.txt file2.txt
# Copies the file file1.txt to file2.txt
❯ cp -r dir1/ dir2/
# Copies entire directory “dir1” to “dir2”
➏ mv
Move
❯ mv file1.js images/
# Moves the file to images/
❯ mv file1.js file2.js
# Renames the file1.js to file2.js
➐ touch
❯ touch new_file
# Creates a new empty file “new_file”
❯ touch -m old_file
# Changes the modification time
➑ cat
Concatenate
⬙ It is used to view, create, and concatenate files.
❯ cat file.txt
# Lists the contents of file1.txt to std output
❯ cat > file.txt
# Creates a new file
❯ cat file1 file2 > file3
# Concatenates file1 & file2 to file3
➒ rm
Remove
❯ rm file1.txt
# Removes a file
❯ rm -r dir1
# Removes an empty directory
❯ rm -rf dir2
# Removes any directory
➓ find
Search based on a regular expression
❯ find ./ -name “xyz”
# Finds files and directories whose name is xyz
❯ find ./ -type f -name “*.java”
# Finds files whose name ends with .java
➊➊ grep
Global Regular Expression Print
❯ grep “hello” message.txt
# Lists all lines of “message.txt”
# that contain “hello”
❯ grep -c “hi” message.txt
# Outputs the number of lines in
# “message.txt” that contain “hi”
➊➋ head
❯ head message.txt
# Outputs first 10 lines of message.txt
❯ head -n 5 message.txt
# Outputs first 5 lines of message.txt
➊➌ tail
❯ tail message.txt
# Outputs last 10 lines of message.txt
❯ tail -n 5 message.txt
# Outputs last 5 lines of message.txt
❯ tail -f app.log
# Shows new entries in app.log
# as and when they get added
➊➍ diff
Difference
❯ diff /dir1/package.json /dir2/package.json
# Compare the contents of the two files
# line by line and lists out all differences
➊➎ alias
❯ alias lsa=”ls -a”
# Creates a new alias “lsa” for “ls -a” command
❯ alias
# Lists all aliases for the current session
— More Useful Commands —
❯ echo
Displays the given text in the terminal
❯ which
Shows the directory where the command is present
❯ whoami
Displays the username of who currently is using this session
❯ man
Displays the manual page of any command
❯ tar
Creates and extracts an archive file
❯ chmod
Changes the mode (permission) of a file
❯ chown
Changes the ownership
❯ du
Checks how much space a file or a directory takes
❯ ps
Lists the processes that the current shell session is running
❯ kill
Kills (terminates) a process
❯ free
Shows the amount of free memory
❯ vmstat 10
Every 10 seconds, show statistics
❯ iotop
Displays the disk IO usage details
❯ systemctl
Manages systemd and services
❯ journalctl
Views systemd, kernel, and journal logs
❯ env
Prints list of environment variables
❯ host
Does DNS lookup operations
❯ hostname
Obtains the DNS name
❯ ping
Checks the network connectivity b/w host and server
❯ curl
Transfers data to or from a server
❯ wget
Retrieves/downloads content from the internet
❯ history
Displays all the commands used in the past
❯ clear
Clears the terminal window
❯ sudo
Allows the current user to act as a superuser or, a root user for running a specific command
❯ exit
Ends a shell session and closes the terminal
