🖥️ Basic SSH Commands

Here is a list of essential SSH commands commonly used when working on a Linux server.

📂 File & Directory Commands

• ls: List files/directories
• ls -al: List all files with details, including hidden ones
• cd /path: Change to a specific directory
• cd ~: Go to home directory
• cd -: Go to the previous directory
• cd ..: Go up one directory
• cat filename.txt: Print file contents
• tail -f /var/log/messages: Continuously view log updates
• more /etc/userdomains: View file one screen at a time
• touch filename: Create an empty file
• rm filename: Delete a file
• rm -rf folder/: Delete folder and all contents (⚠️ dangerous!)
• cp source target: Copy files
• ln -s original linkname: Create a symbolic link

📝 Text Editors

• pico file: Simple editor
• vi file: Advanced editor (steep learning curve)

🔍 Searching & Monitoring

• grep pattern file: Find text pattern in a file
• grep -v pattern file: Exclude lines matching the pattern
• w: Who is logged in and from where
• last: Recent logins
• netstat -an: Active network connections
• Top: Live System Resource Monitor
• ps aux: List all running processes
• ps aux --forest: Hierarchical process list
• kill -9 PID: Force terminate a process

💾 Disk & File Info

• file *: Identify file types
• du -sh: Total disk usage of the current directory
• du -sh *: Disk usage by each item
• wc -l file: Count lines in a file

🛠️ Combining Commands

• command1 | command2: Pipe the output of one into another
• command > file: Redirect output to file (overwrite)
• command >> file: Append output to file
• command < file: Use file as input

Examples:

grep User /usr/local/apache/conf/httpd.conf | more
last -a > /root/lastlogins.tmp
tail -10000 /var/log/exim_mainlog | grep domain.com | more
netstat -an | grep :80 | wc -l
mysqladmin processlist | wc -l
mysqldump -u username -ppassword dbname > file.sql
tar -zcvf archive.tar.gz directory/
tar -zxvf archive.tar.gz
mysql -uusername -ppassword database_name
  

⚠️ Note: Always double-check before running commands like rm -rf or kill -9 to avoid accidental damage.