Overview
md5sum generates a unique MD5 hash value for a file, allowing for quick detection of any changes. It is primarily used for verifying the integrity of downloaded files and plays a crucial role in confirming if a file is identical to its original.
Key Features
- Calculate file MD5 checksums
- Verify integrity using checksum files
- Support for standard input/output
Key Options
The main options for the md5sum command control how checksums are calculated and verified.
Operation Control
Generated command:
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Description:
`md5sum` Executes the command.
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Usage Examples
Learn how to verify file integrity through various usage examples of the md5sum command.
Calculate MD5 checksum of a file
md5sum my_document.txtCalculates and outputs the MD5 checksum for a specified file.
Save checksum to a file
md5sum my_document.txt > my_document.md5Calculates the MD5 checksum of a file and saves the result to a separate file.
Verify integrity using a saved checksum file
md5sum -c my_document.md5Verifies the integrity of the original file using a previously saved `.md5` file. Outputs 'OK' on success and 'FAILED' on failure.
Calculate checksums for multiple files
md5sum file1.txt file2.txt file3.txtCalculates MD5 checksums for multiple files at once.
Calculate MD5 from standard input
echo "Hello World" | md5sumCalculates the MD5 checksum of text passed via standard input instead of a file.
Show warnings on verification failure and continue
md5sum -c --warn my_files.md5When a checksum file has multiple entries, this option displays warnings for failures but continues with the remaining verifications.
Tips & Precautions
Points to note and useful tips when using md5sum.
MD5 Security Vulnerabilities
MD5 is known to be vulnerable to collision attacks, meaning two files with different content can have the same MD5 checksum. Therefore, for security-critical applications, it is recommended to use stronger hash algorithms like SHA-256 instead of MD5.
Alternative Hash Algorithms
For higher security requirements, consider the following commands:
- sha256sum: Calculate and verify SHA-256 checksums
- sha512sum: Calculate and verify SHA-512 checksums
Utilizing Standard Input
md5sum can calculate checksums from data received via standard input (stdin) through a pipe (|). This is useful for checking the checksum of data that is not saved to a file.