Appendix B — Linux Cheat Sheet

B.1 Getting help

# Print the manual of the command <ls>
man ls

# Print examples of the command <ls>
curl https://cheat.sh/ls

B.2 Working w/ directories

B.2.1 Directory content

# List the content of the current directory
ls .

# List the content of the current directory (shortcut)
ls

# List the content of the folder <sancho> (relative path)
ls sancho

# List the content of the folder <sancho> (absolute path)
ls /media/sancho

# List the content including hidden files
ls -a

# List the content in a table-like format
ls -l

# List the content in a table-like format with hidden files
ls -al

# List the content recursively
ls -R

# List the content in a table-like format and human-readable
ls -lh

# List the content in a tree-like format
tree

# List the content including hidden files
tree -a

# Limit to two levels
tree -L 2

B.2.2 Directory navigation

# Print the current directory
pwd

# Go to your home directory
cd /home/jdoe

# Go to your home directory (shortcut)
cd ~

# Go to your home directory (shortcut)
cd

# Move one level up (parent directory)
cd ..

# Move two levels up
cd ../..

# Go to a directory (relative path)
cd .ssh

# Go to a directory (absolute path)
cd ~/.ssh

# Go to a subdirectory (absolute path)
cd /media/sancho

B.2.3 Creating directories

# Create the directory <foo> in the current directory
mkdir ./foo

# Create the directory <foo> in the current directory (shortcut)
mkdir foo

# Create nested directories
mkdir -p foo/bar/baz

# Create <foo/bar> and <foo/baz> directories
mkdir -p foo/{bar,baz}

B.2.4 Copying directories

# Copy a directory and its content
# (if bar/ exists foo/ is copied inside)
cp -r foo bar

# Copy only the content of a directory
# (bar/ must exist)
cp -r foo/* bar/

# Copy a directory and ask before overwriting
cp -i -r foo/* bar/

B.2.5 Moving directories

# Move a directory into an existing directory
mv source existing_directory

B.2.6 Renaming directories

# Rename a directory (the target is not an existing directory)
mv source target

B.2.7 Deleting directories

# Delete a directory and its content
rm -r foo

# Delete a subdirectory
rm -r foo/bar

# Delete a directory and its content (force mode)
rm -rf foo

B.3 Working w/ files

B.3.1 Creating files

# Create a new empty file in the current directory
touch newfile.txt

# Create a new file and add content on-the-fly
echo 'Line 1\nLine 2' > newfile.txt

# Create and open a new file in the NANO text editor
# (press CTRL + X, then Y and ENTER to save and exit)
nano newfile.txt
                                         
# Create a new file and add content interactively
# (press CTRL + D to save the file)
cat > newfile.txt

B.3.2 Editing files

# Add content at the end of an existing file
echo 'Line 3\nLine 4' >> file.txt

# Open an existing file in the NANO text editor
# (press CTRL + X, then Y and ENTER to save and exit)
nano file.txt

# Add content interactively to an existing file
# (press CTRL + D to save the file)
cat >> file.txt

B.3.3 Printing file content

# Print file content
cat file.txt

# Open a file for interactive reading
less file.txt

# Print the first 10 lines of a file
head file.txt

# Print the first 6 lines of a file
head -n 6 file.txt

# Print the last 10 lines of a file
tail file.txt

# Print the last 6 lines of a file
tail -n 6 file.txt

# Dynamic - Useful for logs
tail -f file.txt

B.3.4 Copying files

# Copy a file in the same location
cp file.txt copy.txt

# Copy a file in a different directory
cp file.txt folder/copy.txt

B.3.5 Moving files

# Move a file to a new location
mv file.txt new/location/

B.3.6 Renaming files

# Rename a file
mv file.txt new_name.txt

# Move and rename a file
mv file.txt new/location/new_name.txt

B.3.7 Deleting file

# Delete a file
rm file.txt

# Delete a file (force mode)
rm -f file.txt

B.3.8 Joining files

# Merge two files in one
cat file-1.txt file-2.txt > file-3.txt

B.4 Useful commands

# Clear the terminal
clear

# Get the size of the current directory
du -sh .

# Print the command lines history
history

# Search for a previous command
# CTRL + R and type some characters of the command

# Create a new screen
screen -S screen_name

# Detach a screen
# (press CTRL + A + D to leave the screen)

# Reattach a screen
screen -r screen_name

# List existing screens
screen -ls

# Kill all R processes for a specific user
killall -u jdoe R

# Kill all RStudio processes for a specific user
killall -u jdoe rsession

# System monitoring utilities
top
htop
btop

# Count number of files (and folders) in the current directory
ls | wc -l

# List all files/folders matching a pattern
ls | grep "\\.md$"

# List all files/folders matching a pattern (case insensitive)
ls | grep -i "\\.md$"

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