Linux Command Reference #

# Check current shell
echo $SHELL
echo $0
env | grep SHELL
ps

type    # Show how a command name is interpreted
which   # Show which executable will be used
man     # Display manual pages
apropos # Search manual pages
info    # Display info pages
whatis  # Display one-line manual page descriptions
alias   # Create command aliases

# View file contents
cat file.txt
head file.txt    # Show first lines
tail file.txt    # Show last lines
less file.txt    # Interactive file viewer

# Text manipulation
cut             # Cut sections from each line
tr              # Translate or delete characters
sort            # Sort lines of text
uniq            # Report or omit repeated lines
wc              # Print line, word, and byte counts
grep            # Print lines matching a pattern

# Basic tar operations
tar -czf archive.tar.gz file1 file2    # Create compressed archive
tar -tzf archive.tar.gz                # List archive contents
tar -xvzf archive.tar.gz               # Extract archive

# Tar with progress (Linux)
tar cf - /folder | pv -s $(du -sb /folder | awk '{print $1}') | gzip > archive.tar.gz

# Tar with progress (macOS)
tar cf - /folder | pv -s $(($(du -sk /folder | awk '{print $1}') * 1024)) | gzip > archive.tar.gz

cp -r sourceFolder targetFolder        # Copy directory recursively
cp source dest                         # Copy file
scp sourceFile user@host:remotePath    # Secure copy to remote host
rsync -av source/ dest/                # Efficient file synchronization

ps              # Display process status
top             # Display and update sorted process information
jobs            # List jobs
bg              # Run job in background
fg              # Run job in foreground
kill            # Send signal to process
killall         # Kill processes by name
shutdown        # Shutdown or restart system

env             # Display environment variables
printenv        # Print environment variables
clear           # Clear terminal screen
history         # Display command history
dmesg           # Display kernel messages

id              # Display user identity
chmod           # Change file mode
umask           # Set default file permissions
su              # Switch user
sudo            # Execute command as superuser
chown           # Change file owner
chgrp           # Change file group
passwd          # Change user password
chsh            # Change login shell
echo $SHELL     # show current shell

# Get yesterday's date
date -d "yesterday 13:00" '+%Y-%m-%d'

# Format date
date '+%Y-%m-%d %H:%M:%S'

sips -s format [image type] [file name] --out [output file]

# Convert image format
sips -s format jpeg input.png --out output.jpg

# Number range
for i in {1..10}
do
    echo $i
done

# Conditional statements
echo "One for ${1:-you}, one for me."

# Using tr
cat file.txt | tr '\n' ','

# Using awk
cat file.txt | awk 'BEGIN{ORS=","}{print}'

# Using xargs and sed
cat file.txt | xargs | sed 's/ /,/g'

cat > test.txt
# Type content
# Press Ctrl+D to finish