A practical guide to the Linux command line

# Where am I?
pwd
 
# List files (with details)
ls -la
 
# Change directory
cd /path/to/directory
 
# Go up one level
cd ..
 
# Go to home directory
cd ~
 
# Go to previous directory
cd -

# Create a file
touch newfile.txt
 
# Create a directory
mkdir my-project
 
# Create nested directories
mkdir -p projects/my-app/src
 
# Copy a file
cp source.txt destination.txt
 
# Copy a directory
cp -r source-dir/ destination-dir/
 
# Move or rename
mv oldname.txt newname.txt
 
# Delete a file
rm unwanted-file.txt
 
# Delete a directory and its contents
rm -rf old-project/

# Show entire file
cat config.yaml
 
# Show first 20 lines
head -20 logfile.txt
 
# Show last 20 lines
tail -20 logfile.txt
 
# Follow a file as it updates (great for logs)
tail -f /var/log/syslog
 
# Search inside a file
grep "error" logfile.txt
 
# Search recursively in a directory
grep -r "TODO" ./src/

# Make a script executable
chmod +x script.sh
 
# Set specific permissions (owner: read/write/execute, others: read/execute)
chmod 755 script.sh
 
# Change file owner
chown user:group file.txt

# Show running processes
ps aux
 
# Find a specific process
ps aux | grep nginx
 
# Kill a process by PID
kill 12345
 
# Kill a process by name
pkill nginx
 
# Show system resource usage
htop

# Find all TypeScript files containing "useState"
grep -r "useState" ./src/ | grep ".tsx"
 
# Count the number of files in a directory
ls | wc -l
 
# Sort a file and remove duplicates
sort names.txt | uniq
 
# Save command output to a file
ls -la > file-list.txt
 
# Append to a file
echo "new line" >> file.txt