Essential Linux Commands (+100)

A comprehensive list of essential Linux commands for file operations, networking, process management, system monitoring, and more.

Table of Contents

1. File Operations
2. Directory Operations
3. Process Operations
4. File Permissions
5. Networking
6. Archives & Compression
7. Text Processing
8. Disk Usage
9. System Info
10. Package Management
11. Shell Scripting
12. System Monitoring
13. Search & Find
14. Compression & Archives
15. Others

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1. File Operations

ls                 # List files in the current directory  
ls -R              # List files including subdirectories  
ls -a              # Show hidden files  
ls -al             # Detailed list view with permissions  
cd directoryname   # Change directory  
cd ..              # Move one level up  
pwd                # Display current directory  
cat > filename     # Create a new file  
cat filename       # Display file content  
cat file1 file2 > file3  # Merge two files into a third file  
touch filename     # Create or modify a file  
rm filename        # Delete a file  
cp source destination  # Copy files  
mv source destination  # Move or rename files  
find / -name filename  # Find a file by name  
file filename      # Show file type  
less filename      # View file content page-by-page  
head filename      # View the first 10 lines of a file  
tail filename      # View the last 10 lines of a file  
lsof               # Show opened files by processes  
du -h --max-depth=1  # Show directory sizes  
fdisk              # Disk partition management  

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2. Directory Operations

mkdir directoryname    # Create a directory  
rmdir directoryname    # Delete an empty directory  
cp -r source destination  # Copy directories recursively  
mv olddir newdir      # Rename or move directories  
find / -type d -name directoryname  # Find a directory  

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3. Process Operations

ps                    # Show active processes  
top                   # Show running processes in real-time  
kill pid              # Kill a process by ID  
pkill name            # Kill a process by name  
bg                    # Resume a suspended process in background  
fg                    # Bring a process to the foreground  
fg n                  # Bring job 'n' to foreground  
renice +n [pid]       # Change process priority  

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4. File Permissions

chmod octal filename  # Change file permissions (0-7)  
chown owner filename  # Change file owner  
chgrp group filename  # Change group owner  

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5. Networking

ping host              # Test connectivity  
whois domain           # Get domain WHOIS info  
dig domain             # Get DNS info  
netstat -pnltu         # Show network stats  
ifconfig               # Show network interfaces  
ssh user@host          # Remote login  
scp source dest        # Secure file transfer  
wget url               # Download a file  
curl url               # Send a web request  
traceroute domain      # Trace the route to a domain  
mtr domain             # Real-time network diagnostic tool  
ss                     # Investigate sockets (modern netstat)  
nmap                   # Network scanner  

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6. Archives & Compression

tar cf file.tar files  # Create tar archive  
tar xf file.tar        # Extract tar archive  
gzip file              # Compress file  
gzip -d file.gz        # Decompress file  
zip -r file.zip files  # Create zip archive  
unzip file.zip         # Extract zip archive  

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7. Text Processing

grep pattern files     # Search for pattern in files  
grep -r pattern dir    # Recursively search in directory  
echo 'text'           # Print text  
sed 's/old/new/g' file  # Replace text in file  
diff file1 file2       # Compare files  
wc filename           # Count lines, words, characters  
cut -d':' -f1 /etc/passwd  # Extract first field  

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8. Disk Usage

df                     # Show disk usage  
du                     # Show directory space usage  
free                   # Show memory and swap usage  
whereis app            # Locate installed applications  

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9. System Info

date                  # Show date/time  
cal                   # Show calendar  
uptime                # Show system uptime  
w                     # Show logged-in users  
whoami                # Show current user  
uname -a              # Show system/kernel info  
df -h                 # Show human-readable disk usage  
free -m               # Show memory usage in MB  

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10. Package Management

sudo apt-get update      # Update package list  
sudo apt-get upgrade     # Upgrade all packages  
sudo apt-get install pkg # Install package  
sudo apt-get remove pkg  # Remove package  

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11. Shell Scripting

#!/bin/bash              # Define script interpreter  
$0, $1, ..., $9         # Access script arguments  
if [ condition ]; then ... fi  # If condition  
for i in {1..10}; do ... done  # For loop  
while [ condition ]; do ... done  # While loop  
function name() {...}    # Define function  

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12. System Monitoring

iostat                  # CPU and I/O statistics  
vmstat                  # Process, memory stats  
htop                    # Interactive process viewer  

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13. Search & Find

locate filename         # Find file  
whereis programname     # Locate binary/source/man files  
which commandname       # Show command path  

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14. Compression & Archives

tar -cvf archive.tar dirname/  # Create tar archive  
tar -xvf archive.tar           # Extract tar archive  
tar -jcvf archive.tar.bz2 dirname/  # Create bz2 archive  
tar -jxvf archive.tar.bz2      # Extract bz2 archive  

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15. Others

yes > /dev/null &       # Max out CPU usage  
:(){ :|:& };::          # Fork bomb (Do NOT run!)  

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Usage

• Use man command to get detailed information about a specific command.
• These commands are useful for daily system administration and automation tasks.

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Contributing

Feel free to submit pull requests for improvements and additional commands.

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License

This list is open-source and available under the MIT License.