The Real Linux World
Mark Sargent
powderkeg at snow.email.ne.jp
Thu Apr 28 06:26:36 UTC 2005
Hi All,
tasty heading..? Ok, whilst I enjoy spinning people with the following,
"Nah, mate, don't use Windows", which usually gets the suprised
response, "oh, what do u use, MAC". Of which I reply, "ah, u all know
what I reply with". BUT, I feel I'm not really a Linux person unless
I've mastered, Shell Programming, where I believe the real power of
Linux World exists. Anyway, enough dribble, and on to my question of the
day. I'm following this tut,
http://www.tldp.org/LDP/abs/html/sha-bang.html
and in the code on that page, there is are variables, $1 and $LINES. Um,
what are they..?
if [ -n "$1" ]
# Test if command line argument present (non-empty).
then
lines=$1
else
lines=$LINES # Default, if not specified on command line.
fi
and then further down, I see this use of one of them,
tail -$lines messages > mesg.temp # Saves last section of message log file.
mv mesg.temp messages # Becomes new log directory.
Can anyone explain this in plain English.? I understand that a portion of messages is being written to mesg.temp,
and that the rest is deleted. Just don't get where $1 and $LINES is being generated from. Cheers.
Mark Sargent.
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