Mr Joe Steeve (ILUGC-Member) & Team has developed the IJammer, an
Instant Messenger Jammer. IJammer is a Daemon that runs on one
workstation of a LAN and prevents any IM traffic on that LAN.
URL: http://sarovar.org/projects/ijammer/

One Day One Command
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sha1sum – Compute & Check Secure Hash Algorithm Std 1 message digest.

Summary:

`sha1sum’ computes a 160-bit checksum/fingerprint/message-digest for
each specified file. `sha1sum’ can also determine whether a file &
checksum are consistent. The sums are computed as described in
FIPS-180-1 (www.itl.nist.gov/fipspubs/fip180-1.htm).

Example:

$ sha1sum file — Compute and print the MD5 checksum of that file.

$ sha1sum -c input.txt — Read checksum and filename from the file and
validate checksums.

$ sha1sum -w -c input.txt — Same as above and warn if the checksums
format is wrong in the file.

$ sha1sum –status -c input.txt — Indicate the status in exit status
code.

Read: man sha1sum

Format of input.txt :

2bff10a7855964335a86e84efb5f4ce9c40d4cfd file1
e62341664decd9f55896ab3635697de29ed1077f file2
9b088ddc22456233a76 file3