md5sum Check Command

MD5 is the abbreviation of Message-digest algorithm 5 (Information-Digest algorithm), which is widely used in encryption and decryption technology, which can be said to be the "digital fingerprint" of the file. Any file, whether executable, image, temporary, or any other type of file, no matter how large it is, has and has only one unique MD5 value, and if the file is modified, its MD5 value will change. Therefore, we can verify whether the file has been "tampered" by comparing the MD5 value of the same file.

What's the use of MD5?

When we download the file, if you want to know the download of this file and the original file of the site is the same, you can give yourself to download the file to do a MD5 check. If the obtained MD5 value is the same as the site publication, you can confirm that the downloaded file is complete. If there is a difference, the file you downloaded is incomplete: either an error occurred during the download of the network, or the file has been modified by someone else. It is best not to use a virus to prevent others from changing the file.

When we use e-mail to send a friend a file, you can send the file's MD5 value to tell each other, so that the friend receives the file can be verified, to determine whether the file is safe.

Another example: After the installation of the system can give the system files to do a MD5 check, after a period of time if you suspect that some files were replaced, then you can give those suspected files to do a MD5 check, if and the previous MD5 check code is not the same, then you can certainly have a problem.

Using md5sum under Linux, use the command directly: Md5sum file

Reference: Linux command in detail: md5sum command

md5sum Check Command