He would need those in a moment. He also jotted down the size
of the login file.
Instead of tearing out the old program and sewing in a completely new
one, Anthrax decided to overlay his patch by copying it onto the top
of the old program. He uploaded his own login patch, with his master
password encased inside it, but he didn't install it yet. His patch
was called `troj'--short for Trojan. He typed:
cat
/bin/login
The cat command told the computer: `go get the data in the file called
"troj" and put it in the file "/bin/login"'. He checked the piece of
paper where he had scribbled down the original file's creation and
modification dates, comparing them to the new patch. The creation date
and size matched the original. The modification date was still wrong,
but he was two-thirds of the way home.
Anthrax began to fasten down the final corner of the patch by using a
little-known feature of the command:
/usr/5bin/date
Then he changed the modification date of his login patch to the
original login file's date.
He stepped back to admire his work from a distance. The newly
installed patch matched the original perfectly. Same size.
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