Analyzing disk usage and space allocation on Linux and Unix-like operating systems

• options: Various options to customize the output, such as -h for human-readable sizes or -s for summary.
• directory or file: The directory or file for which you want to calculate disk usage. If not specified, du starts from the current directory.

Example 1: Calculating Disk Usage of a Directory

To calculate the disk usage of a directory, simply provide the directory path as an argument to the du command. For example:

du /home/user/documents

This command will display the disk space used by the /home/user/documents directory and its subdirectories.

Example 2: Human-Readable Output

The -h option (or --human-readable) can be used to display sizes in a more human-friendly format, such as kilobytes (KB), megabytes (MB), or gigabytes (GB). For instance:

du -h /var/log

This command will provide a human-readable summary of the disk usage within the /var/log directory.

Automating Disk Space Analysis in Shell Scripts

To automate disk space analysis within a shell script, you can capture the du command’s output and use it for various purposes, such as generating reports or triggering actions based on space usage. Here’s an example shell script that calculates and displays the disk space used by a directory:

#!/bin/bash
TARGET_DIRECTORY="/data/storage"
SPACE_USED=$(du -sh "$TARGET_DIRECTORY" 2>/dev/null)

if [ $? -eq 0 ]; then
    echo "Disk space used by $TARGET_DIRECTORY:"
    echo "$SPACE_USED"
else
    echo "Error: Directory not found or permission denied."
fi

In this script:

• We specify the target directory in the TARGET_DIRECTORY variable.
• We use du -sh to calculate the disk usage of the target directory and suppress any error messages by redirecting them to /dev/null.
• We check the exit status of the du command using $? to determine if the directory was found and accessible.
• Depending on the exit status, we either display the disk space usage or an error message.

Advanced du Command Options

The du command offers several advanced options to customize its behavior and tailor the output to specific requirements. Some useful options include:

• -c or --total: Display a total sum of all sizes in the specified directories.
• -a or --all: Display sizes for all files and directories, not just directories.
• --exclude: Exclude specific directories or files from the calculation.
• -d or --max-depth: Limit the depth of the directory tree to analyze.

Example: Finding the Largest Files in a Directory

To find the largest files within a directory and its subdirectories, you can use the find command in conjunction with du. Here’s a script that lists the top N largest files within a directory:

#!/bin/bash
TARGET_DIRECTORY="/data/documents"
NUM_FILES=5  # Change this value to the desired number of files to list

echo "Top $NUM_FILES largest files in $TARGET_DIRECTORY:"
find "$TARGET_DIRECTORY" -type f -exec du -h {} + | sort -rh | head -n "$NUM_FILES"

This script uses find to locate files within the specified directory, and then for each file found, it calculates its disk usage with du. The results are sorted in descending order by size, and the top N largest files are displayed.

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