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Old 11-15-2009, 04:45 AM   #1
jcky
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Registered: Feb 2008
Location: China-Shanghai
Distribution: Rhel&Suse
Posts: 82

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Bash Script


#!/bin/bash
# alive2.sh
# Checks to see if hosts 192.168.1.100-192.168.1.105 are alive
# Iterate through IP address
for n in {100..105};
do
host=192.168.1.$n
ping -c2 $host &> /dev/null
if [ $? = 0 ];
then
echo "$host is UP"
else
echo "$host is DOWN"
fi
done

What is the purpose of "if [ $? = 0 ];"?

I need your kind help.

;p
 
Old 11-15-2009, 04:55 AM   #2
pixellany
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Registered: Nov 2005
Location: Annapolis, MD
Distribution: Arch/XFCE
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"$?" is the return code from a command. "0" means the command executed successfully.

You could also do this:

Code:
if $(ping -c2 $host &> /dev/null); then
     do stuff
else
     do other stuff
fi

(Always use [CODE] tags to make code easier to read.)

Last edited by pixellany; 11-15-2009 at 05:00 AM.
 
Old 11-16-2009, 11:46 PM   #3
stevenworr
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Registered: Oct 2008
Posts: 13

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I can't resist:

Code:
for n in {100..105}
do
    host=192.168.1.$n
    echo -n "$host is "
    ping -c2 $host > /dev/null 2>&1 && echo up || echo down
fi
done
 
Old 11-17-2009, 07:54 AM   #4
pixellany
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Registered: Nov 2005
Location: Annapolis, MD
Distribution: Arch/XFCE
Posts: 17,802

Rep: Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738
Quote:
Originally Posted by stevenworr View Post
I can't resist:

Code:
for n in {100..105}
do
    host=192.168.1.$n
    echo -n "$host is "
    ping -c2 $host > /dev/null 2>&1 && echo up || echo down
fi
done
Nice!! (but take out the "fi")
 
  


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