50-linux-productions-level-powerfull-commands

50 linux productions level powerfull commands. these commands are very usefull in real environment in devops, sysops, linux-administrator roles, and in shell scripting

Linux Powerfull Commands:::::::::::::::::::

50 Linux commands that are very useful for DevOps tasks, along with brief explanations and examples:

rsync - Remote File Copy:

Efficiently copy files between local and remote systems.

rsync -avz /local/path user@remote:/remote/path

awk - Text Processing:

A powerful text processing tool for pattern scanning and reporting.

#cat logfile | awk '/error/ {print $1, $2}'

sed - Stream Editor:

Perform text transformations on input streams.

#cat file.txt | sed 's/old/new/g' 4. find - Search for Files:

Search for files in a directory hierarchy.

find /path/to/search -name "*.txt"

tar - Archive and Compress:

Create compressed archive files.

tar -czvf archive.tar.gz /path/to/directory

curl - Transfer Data with URLs:

Transfer data from or to a server.

curl -O https://example.com/file.txt

lsof - List Open Files:

List information about files opened by processes.

lsof -i :80

iptables - IP Packet Filter:

Configure IP packet filter rules.

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

grep - Search Text Patterns:

Search for patterns in files.

grep "pattern" /path/to/search

awk '{print $NF}' - Extract Last Column:

Extract and print the last column from a file.

cat data.txt | awk '{print $NF}'

tee - Redirect Output to File and Terminal:

Redirect output to a file and display it on the terminal.

command | tee output.txt

htop - Interactive Process Viewer:

Display an interactive process viewer.

Htop

netstat - Network Statistics:

Display network connections, routing tables, interface statistics, masquerade connections, etc.

netstat -tulpn

awk '!seen[$0]++' - Remove Duplicate Lines:

Remove duplicate lines from a file.

awk '!seen[$0]++' file.txt

tail -n 20 - Display Last 20 Lines:

Display the last N lines of a file.

tail -n 20 logfile.txt

du -h - Show Disk Usage:

Display disk usage of files and directories.

du -h /path/to/directory

ps aux | grep process_name - List Processes:

List all processes and filter by name.

ps aux | grep nginx

watch -n 1 command - Execute Command Periodically:

Run a command repeatedly at a specified interval.

watch -n 1 "ps aux | grep process_name"

df -h - Display Free Disk Space:

Show free disk space on mounted filesystems.

df -h

nc -l 8080 - Simple Netcat Server:

Start a simple server using netcat.

nc -l 8080

cut -d' ' -f1 - Extract First Column:

Extract and print the first column from a file.

cut -d' ' -f1 file.txt

journalctl - View System Logs:

Query and display messages from the journal.

journalctl -xe

chmod +x filename - Make File Executable:

Grant execute permission to a file.

#chmod +x script.sh

chown user:group filename - Change File Owner:

Change the owner and group of a file.

chown user:group file.txt

nohup command & - Run Command in Background:

Run a command that keeps running even after logging out.

nohup ./script.sh &

head -n 10 - Display First 10 Lines:

Display the first N lines of a file.

head -n 10 file.txt

fdisk -l - List Partitions:

Display the partition table for all disks.

fdisk -l

history - View Command History:

Display the command history for the current session.

History

uptime - Check System Uptime:

Display how long the system has been running.

Uptime

crontab -e - Edit Cron Jobs:

Edit the crontab file to schedule jobs.

crontab -e

ip a - Show IP Addresses:

Display network interfaces and their IP addresses.

ip a

systemctl status service_name - Check Service Status:

View the status of a systemd service.

systemctl status ssh

echo "Hello, World!" > file.txt - Write to File:

Write text to a file (overwrites existing content).

echo "New content" > file.txt

useradd username - Add User:

Add a new user to the system.

useradd john_doe

passwd username - Set User Password:

Set or change the password for a user.

passwd john_doe

ps -ef - Show All Processes:

Display information about all processes.

ps -ef

kill -9 process_id - Forcefully Kill Process:

Terminate a process forcefully.

kill -9 12345

scp file.txt user@remote:/path - Secure Copy:

Copy files securely between local and remote systems.

#scp localfile.txt user@remote:/path

free -m - Display Free Memory:

Show the amount of free and used memory.

free -m

systemctl restart service_name - Restart Service:

Restart a systemd service.

systemctl restart apache2

echo $VARIABLE - Display Environment Variable:

Display the value of an environment variable.

echo $HOME

ps aux | sort -rk 3,3 - Top CPU Consuming Processes:

List processes sorted by CPU usage.

ps aux | sort -rk 3,3

tail -f /var/log/auth.log - Monitor Authentication Logs:

Continuously monitor authentication logs.

tail -f /var/log/auth.log

systemctl stop service_name - Stop Service:

Stop a systemd service.

systemctl stop nginx

wget - Download Files from the Web:

Download files from the internet.

wget https://example.com/file.txt

grep -i "error" /path/to/log/*.log - Case-Insensitive Search:

Search for errors in logs regardless of case.

grep -i "error" /path/to/log/*.log

df -Th - Display Disk Space Usage with Type:

Show disk space usage with filesystem type.

df -Th

journalctl --since "2023-01-01" - View Logs Since Date:

Display journal logs since a specific date.

journalctl --since "2023-01-01"

systemctl enable service_name - Enable Service at Boot:

Enable a systemd service to start at boot.

systemctl enable apache2

awk -F: '//home/ {print $1, $7}' /etc/passwd - Extract

User and Home Directory:

Extract and print username and home directory from /etc/passwd.

awk -F: '//home/ {print $1, $7}' /etc/passwd

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