Use of md5sum in linux

The MD5 algorithm is often used to verify the integrity of network file transmission and prevent file tampering. MD5 is short for packet digest algorithm (Message-DigestAlgorithm5), this algorithm for any length of information by bit calculation, generate a binary length of 128 bits (hexadecimal length is 32 bits... the MD5 algorithm is often used to verify the integrity of network file transmission and prevent file tampering. MD5
Message Digest Algorithm (Message-Digest Algorithm)
5), this algorithm computes information of any length by bit, and generates a binary length of 128 bits (the hexadecimal length is 32 bits) "fingerprint" (or "message digest") of, different files are generated
The possibility of the same message digest is very small.
In linux or Unix, md5sum is a tool program used to calculate and verify the file message digest. Generally, after Linux is installed, the md5sum tool runs directly on the command line terminal.
1. run the following command to generate a fingerprint (packet Digest) using md5sum:

Md5sum file> file. md5

Or
Md5sum file> file. md5
You can also output the message digest of multiple files to an md5 file. the wildcard * is used. for example, there are several iso files in a directory, output the abstract of these iso files to iso. in the md5 file, the command is as follows:

Md5sum *. iso> iso. md5
2. use the md5 message digest to verify the file. There are two methods:
Put the downloaded file and the file. md5 digest file of the file in the same directory, and then run the following command for verification:
Md5sum-c file. md5
Then, if the verification is successful, the output is correct.



Md5sum passwd. bak/etc/passwd