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Shell command: md5sum

md5sum computes an MD5 message digest or checks a file against the previously created message digest.

First, we create a file (file.txt) and compute its MD5 digest and redirect it into file.md5sum.

echo "one: foo"    >  file.txt
echo "two: bar"   >>  file.txt
echo "three: baz" >>  file.txt

md5sum file.txt > file.md5sum

Then, we use file.md5sum to check the integrity of file.txt.

md5sum -c file.md5sum

We tamper with file.txt …

sed -i 's/two/TWO/' file.txt

… and check its integrity again:

md5sum -c file.md5sum

See also