In their day-to-day work, DevOps Engineers often need to execute numerous Linux commands, and remembering each command can be challenging. Below is a curated list of essential Linux commands covering various topics frequently used by DevOps Engineers:
- VI & Nano Editor Shortcuts
- Common DevOps Tasks
- Linux Networking Commands
- Connectivity Testing Commands
- IP Address Configuration Commands
- Useful Networking Tools
- Commands Related to ACL, ARP, Route Tables, and Namespace Operations
h : Move cursor left
j : Move cursor dow
k : Move cursor up
l : Move cursor right
i : Insert mode (start inserting before the cursor)
a : Append mode (start inserting after the cursor)
x : Delete character at the cursor
dd : Delete the current line
yy : Yank (copy) the current line
p : Paste the yanked or deleted text
h : Move cursor left
j : Move cursor dow
k : Move cursor up
l : Move cursor right
SAVE AND QUIT
h : Move cursor left
j : Move cursor dow
k : Move cursor up
l : Move cursor right
/pattern: Search for 'pattern':s/old/new/g` : Replace 'old' with 'new' in the entire file
u: Undo
Ctrl + r : Redo
v : Enter Visual mode
V : Enter Visual Line mode
y : Yank selected text
0 : Move to the beginning of the line
$ : Move to the end of the line
:n : Move to line number 'n'
0 : Move to the beginning of the line
$ : Move to the end of the line
:n : Move to line number 'n'
:e filename : Open a file
:w filename : Save as a different filename
:q! : Quit without saving changes
Alt + A : Mark text for copying
Ctrl + K : Cut marked text
Ctrl + U : Paste cut text
Ctrl + k : Cut (delete) the current line
Ctrl + u : Paste the cut text
Ctrl + o : Write changes to the file
Ctrl + x : Exit nano
Ctrl + w : Search for text
Ctrl + \ : Replace text
Ctrl + f : Move forward one page
Ctrl + b : Move backward one page
Ctrl + arrow keys : Move cursor by word
Ctrl + k : Cut (delete) the current line
Ctrl + u : Paste the cut text
Ctrl + o : Write changes to the file
Ctrl + x : Exit nano
Alt + ,` : Go to line number
HELP
Ctrl + X : Close nano (it will ask to save changes)
- ls - List Files and Directories: List the contents of a directory.
ls -l- cd - Change Directory: Navigate to a different directory.
bash cd /home/user/documents
- pwd - Print Working Directory: Display the current directory's full path.
pwd- mkdir - Make Directory: Create a new directory.
mkdir new_folder- rm - Remove: Delete files or directories.
rm file.txt- cat - Concatenate and Display: View the content of a file.
cat file.txt- nano - Text Editor: Open a text file for editing.
nano file.txt- grep - Search Text: Search for text patterns in files.
grep "pattern" file.txt- find - Search Files and Directories: Search for files and directories.
find /path/to/search -name "file_name"- chmod - Change File Permissions: Modify file permissions.
chmod 755 file.sh- chown - Change Ownership: Change the owner and group of a file or directory.
chown user:group file.txt- ps - Process Status: Display running processes.
ps aux- top - Monitor System Activity: Monitor system processes in real-time.
top- kill - Terminate Processes: Terminate a process using its ID.
kill PID- wget - Download Files: Download files from the internet.
wget https://example.com/file.zip- curl - Transfer Data with URLs: Transfer data to or from a server.
curl -O https://example.com/file.txt- tar - Archive and Extract: Create or extract compressed archive files.
tar -czvf archive.tar.gz folder- ssh - Secure Shell: Connect to a remote server securely.
ssh user@remote_host- scp - Securely Copy Files: Copy files between local and remote systems using SSH.
scp file.txt user@remote_host:/path- rsync - Remote Sync: Synchronize files and directories between systems.
rsync -avz local_folder/ user@remote_host:remote_folder/- df - Disk Free Space: Display disk space usage.
df -h- du - Disk Usage: Show the size of files and directories.
du -sh /path/to/directory- ifconfig - Network Configuration: Display or configure network interfaces (deprecated, use ip).
ifconfig- ip - IP Configuration: Manage IP addresses and network settings.
ip addr show- netstat - Network Statistics: Display network connections and statistics (deprecated, use ss).
netstat -tuln- systemctl - System Control: Manage system services using systemd.
systemctl start service_name- journalctl - Systemd Journal: View system logs using systemd's journal.
journalctl -u service_name- cron - Schedule Tasks: Manage scheduled tasks.
crontab -e- at - Execute Commands Later: Run commands at a specified time.
echo "command" | at 15:30- ping - Network Connectivity: Check network connectivity to a host.
ping google.com- traceroute - Trace Route: Trace the route packets take to reach a host.
traceroute google.com- curl - Check Website Connectivity: Check if a website is up.
curl -Is https://example.com | head -n 1- dig - Domain Information Groper: Retrieve DNS information for a domain.
dig example.com- hostname - Display or Set Hostname: Display or change the system's hostname.
hostname- who - Display Users: Display currently logged-in users.
who- useradd - Add User: Create a new user account.
useradd newuser- usermod - Modify User: Modify user account properties.
usermod -aG groupname username- passwd - Change Password: Change user password.
passwd username- lsof - List Open Files: List open files and processes using them.
lsof -i :port - nc - Netcat: Networking utility to read and write data across network connections.
echo "Hello" | nc host port - scp - Secure Copy Between Hosts: Copy files securely between hosts.
scp file.txt user@remote_host:/path - sed - Stream Editor: Text manipulation using regex.
sed 's/old/new/g' file.txt - awk - Text Processing: Pattern scanning and text processing.
awk '{print $2}' file.txt - cut - Text Column Extraction: Extract specific columns from text.
cut -d"," -f2 file.csv Purpose: Query DNS to obtain domain-related information. Example:
nslookup example.comExplanation: Useful for troubleshooting DNS issues, checking domain information, and resolving IP addresses.
Purpose: A versatile DNS tool for querying DNS servers. Example:
dig example.comExplanation: Provides detailed DNS information, useful for debugging and obtaining specific record types.
Purpose: Connect to a remote server to test network connectivity. Example:
telnet example.com 80Explanation: Useful for checking if a specific port on a remote server is reachable.
Purpose: Trace the route packets take to reach a destination. Example:
traceroute example.comExplanation: Helps identify network issues and understand the path packets take through the internet.
Purpose: Display and configure network interfaces. Example:
ifconfigExplanation: View current network interface configurations and assign IP addresses.
Purpose: A versatile command for network configuration. Example:
ip addr show Explanation: Provides more detailed information than ifconfig and allows advanced network configuration.
Purpose: Establish TCP/UDP connections, making it a versatile networking tool. Example:
nc -zv example.com 80 Explanation: Useful for checking if a port is open and for simple network testing.
Purpose: Display network statistics and connections. Example:
netstat -tulpnExplanation: Helps monitor active network connections, ports, and routing tables.
Purpose: Capture and analyze network traffic. Example:
tcpdump -i eth0Explanation: Useful for debugging network issues, analyzing packets, and monitoring network activity.
Purpose: Download files from the internet. Example:
wget https://example.com/file.txtExplanation: Simplifies downloading files, and is useful for fetching resources from the web.
Purpose: Transfer data from or to a server. Example:
curl https://example.com/api Explanation: Supports a variety of protocols and is handy for testing APIs and fetching web content.
Purpose: Set permissions on files or directories. Example:
setfacl -m u:jane:rw file.txtExplanation: Allows fine-grained control over file and directory permissions.
Purpose: Display or manipulate the ARP cache. Example:
bash `arp -a
Explanation: Shows a mapping between IP addresses and MAC addresses on the local network. .
Purpose: Display or manipulate the IP routing table. Example:
route -n Explanation: Helps monitor active network connections, ports, and routing tables.
sudo ip link add 'myns-1-eth0' type veth peer name 'myns-2-eth0'sudo ip link set 'myns-1-eth0' netns 'mynamespace-1'
sudo ip link set 'myns-2-eth0' netns 'mynamespace-2'sudo ip netns exec 'mynamespace-1' ip addr add 192.168.1.1/24 dev eth0sudo ip link set 'myns-1-eth0' netns 'mynamespace-1'
sudo ip link set 'myns-2-eth0' netns 'mynamespace-2'sudo ip netns exec 'mynamespace-1' ip link set 'lo' up
sudo ip netns exec 'mynamespace-1' ip link set 'eth0' up