Command profile

md5sum For calculating and verifying files MD5 value .

md5sum It is often used to verify the integrity of network file transmission , Prevent documents from being tampered with . In daily work , We can use it to monitor whether important files in the system have been tampered with .

You can also use md5sum Generate the password of the file or user .

Grammar format

md5sum [ Options ] [ file ]

Option description

-b # Use binary mode to read files
-t # Think of the input file as a text file
-c # Read... From the specified file MD5 Check value , And check it
--status # When the verification is successful, no information will be output
-w # When the verification is not correct, the warning message will be output

Application, for example,

Generate passwords or random numbers

[root@centos7 ~]# date | md5sum
1b1f0ba711e7d4931c23fbbd2b328e40 -

Check a file for md5 value

[root@centos7 testdir]# md5sum mingongge1.txt
c5cab5a45a72380ce456a4370bf40348 mingongge1.txt

Check whether a file has been changed

# Extract original file md5 value
[root@centos7 testdir]# md5sum mingongge1.txt >./mingongge.txt.md5
[root@centos7 testdir]# cat mingongge.txt.md5
c5cab5a45a72380ce456a4370bf40348 mingongge1.txt
# Write content
[root@centos7 testdir]# cat >> mingongge1.txt << EOF
> 1
> 2
> 3
> 4
> EOF
[root@centos7 testdir]# md5sum mingongge1.txt -c mingongge.txt.md5
mingongge1.txt: FAILED
md5sum: WARNING: 1 computed checksum did NOT match