NeuralBlitz Unix & Linux — Command Reference
Covers: File Operations · Process Management · Text Processing · Networking · Scripting · System Administration
File System Operations
File Navigation and Listing
The Unix file system follows a hierarchical tree structure with the root directory "/" at the top. Understanding how to navigate this structure efficiently is fundamental to working with Unix systems. Modern Unix systems maintain a consistent directory structure following the Filesystem Hierarchy Standard (FHS).
Common directories include: /bin for essential binaries, /etc for system configuration, /home for user directories, /var for variable data like logs, /tmp for temporary files, /usr for user programs, and /proc for process information.
# Basic navigation
cd /home/user/projects # Change directory
cd ~ # Go to home directory
cd - # Go to previous directory
pwd # Print working directory
ls # List files
ls -la # List all files with details
ls -lh # Human-readable file sizes
ls -lt # Sort by modification time
ls -lS # Sort by file size
ls -R # Recursive listing
ls -1 # One file per line
ls -d */ # List directories only
# Using ls with various options
ls -a # Show hidden files (starting with .)
ls -A # Show hidden files except . and ..
ls -F # Append file type indicators (* / @ |)
ls --color=auto # Colorize output by type
# Advanced listing
ls -l | grep '^d' # List directories only
ls -l | awk '{print $9}' # List just filenames
ls -t | head -n 10 # 10 most recently modified files
find . -type f -ls # Detailed listing with find
File Creation and Manipulation
# Create files
touch newfile.txt # Create empty file
touch -t 202312251200 file # Create with specific timestamp
echo "content" > file.txt # Create with content (overwrite)
echo "content" >> file.txt # Append content
printf "Line1\nLine2\n" > f # Create with newlines
cat > file.txt << EOF # Here-document creation
Multi-line
content
here