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Old 01-21-2011, 08:21 AM   #1
Voyager7
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Registered: Jan 2011
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What does $$ do


hi,
What does $$ do?
it gives back a number but what is it?
Also what are these $?, $$ called?
Having a tough time googling them, so their generic name would help

Thnx
 
Old 01-21-2011, 08:34 AM   #2
sycamorex
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Here you go:
http://tldp.org/LDP/abs/html/interna...s.html#PROCCID

HTH
 
Old 01-21-2011, 10:51 AM   #3
Soji Antony
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Registered: Jul 2010
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$$ is the PID( Process id) of the current process.
For example
Code:
echo $$
gives pid of current shell.

Hope this helps

Last edited by Soji Antony; 01-21-2011 at 10:54 AM.
 
Old 01-21-2011, 11:00 AM   #4
Soji Antony
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Registered: Jul 2010
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Code:
man bash
will give you a detailed explanation

Code:
Special Parameters
?      Expands to the exit status of the most recently executed foreground pipeline.
$      Expands  to  the  process  ID of the shell.  In a () subshell, it expands to the process ID of the current shell, not the subshell.
 
  


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