9. Basic File Management Commands

Effective file management is fundamental to navigating and operating within any command-line environment, especially Linux and Unix-like systems. This section covers essential commands for listing, viewing, manipulating, and organizing files and directories.

9.1. Listing Directory Contents

The ls command is used to list files and directories. It offers various options to customize the output.

Command	Description
ls	List the contents of the current directory.
ls *	List contents of the current directory along with subdirectories.
ls -l	List contents in a long format, showing owner, permissions, date, and size.
ls -a	List all files, including hidden files (those starting with a dot).
ls -t	List files sorted by last modified date in descending order.
ls -rt	List files sorted by last modified date in ascending order.
ls -R	Recursively list files of the current directory and all subdirectories.
ls /path/to/directory	List files in the specified directory.

9.2. Displaying File Contents

These commands allow you to view the content of files, which is crucial for inspecting configuration files, logs, or source code.

Command	Description
cat demo.txt	Display the entire contents of a file. Best for small files.
head demo.txt	Display the first few lines of a file (default is 10).
tail demo.txt	Display the last few lines of a file (default is 10).
tail -f demo.txt	Follow the file, displaying new lines as they are appended. Useful for monitoring logs.
less demo.txt	Display file contents one screen at a time, allowing navigation.
less -p "pattern" demo.txt	Display file contents, starting from the first occurrence of "pattern".
strings -a binaryfile	Extract and print all printable character sequences from a file, useful for examining binary files.
diff file1 file2	Show the differences between two files line by line.
comm file1 file2	Compare two sorted files line by line, showing lines unique to file1, unique to file2, and common to both.

9.3. File Handling Operations

This section covers the core commands for managing files and directories: copying, moving, renaming, and deleting.

9.3.1. Copying Files and Directories

The cp command is used to duplicate files and directories.

Command	Description
cp file1 file2	Copy file1 to a new file named file2.
cp file1 file2 directory1	Copy file1 and file2 into directory1.
cp -R directory1 directory2	Recursively copy the contents of directory1 to directory2.
cp *.txt directory1	Copy all files ending with .txt into directory1.

9.3.2. Moving or Renaming Files and Directories

The mv command is used for both moving files/directories and renaming them.

Command	Description
mv file1 file2	Rename file1 to file2.
mv file1 directory1/	Move file1 into directory1.
mv *.jpg directory1/	Move all files ending with .jpg into directory1.

9.3.3. Deleting Files and Directories

The rm command is used to remove files and directories. Use with caution, as deleted items are typically not recoverable.

Command	Description
rm file1	Remove (delete) file1.
rm file1 file2	Remove both file1 and file2.
rm *.png	Remove all files ending with .png.
rm -d emptyDirectory	Remove an empty directory.
rm -r directory1	Recursively remove directory1 and all its contents (files and subdirectories).

9.3.4. File Linking

Linking allows you to create references to files or directories. There are two main types of links:

• Hard Link: An additional name for an existing file. It points directly to the file's inode. If the original file is deleted, the hard link still provides access to the data.
• Soft Link (Symbolic Link): An indirect pointer to a file or directory. It stores the path to the original file. If the original file is deleted, the soft link becomes broken.

Command	Description
ln file1 link1	Create a hard link named link1 to file1.
ln -s file1 link1	Create a symbolic (soft) link named link1 to file1.

9.3.5. Changing Directory

The cd command is used to navigate between directories in the file system.

Command	Description
cd	Change to the home directory.
cd ~	Change to the home directory.
cd -	Change to the previously current directory.
cd ..	Change to the parent directory (one level up).
cd /	Change to the root directory of the file system.
cd ~/dir1/dir2	Change to a directory relative to the home directory.

9.3.6. Displaying Disk Usage

The du command estimates and displays the disk space used by files and directories.

Command	Description
du	Estimate and display disk space usage for files and directories.
du -h *	Display disk usage in a human-readable format (e.g., KB, MB, GB) for all items in the current directory.

9.3.7. File Ownership and Permissions

Managing file permissions and ownership is critical for security and access control.

Command	Description
chmod	Change file mode bits (permissions).
chown	Change file owner and group.

Understanding and utilizing these basic file management commands will significantly enhance your productivity and control when working with the command line.