Shell script to ping machines

info1686 · 08-03-2009, 05:14 AM

Hi All,
I am trying to write a shell script to ping a set of machines and generate a report.
Here is the script I have written till now:

Code:

#!/bin/bash/

x=`cat machines.txt|wc -l`
for ((i=1;i<=$x;i++))
do
        machine=`sed -n "${i}p" machines.txt`
        echo $machine
        command=`(ping -c 4 $machine) >> output.txt`
        $command
        if [ $? -eq 0 ]
        then
                echo -e "Machine is up"
        fi
done

Still lots has to be done.

the "ping" command returns exit status non-zero if it fails.
However, here even for machines that are down, it prints
"Machine is up"

The same command outside of the script has exit status 1 for the machine that is down.

What can be the issue?

Thanks

catkin · 08-03-2009, 05:25 AM

Hello info1686

It may be instructive to check the value of $command

Code:

        <stuff>
        command=`(ping -c 4 $machine) >> output.txt`
        echo "'$command'"
        $command
        <stuff>

The single quotes inside the double quotes are good practice to show any leading or trailing whitespace characters.

Best

Charles

acid_kewpie · 08-03-2009, 05:28 AM

why are you running "$command"??? that means you'll be RUNNING the output of ping as if it were a program... remove that line and you'll possibly be OK.

acid_kewpie · 08-03-2009, 05:31 AM

That's a pointless for loop too, why are you not just reading in the file itself as the loop input?

while read ipaddress < file.txt
do
...
done

or even

for ipaddress in $(cat file.txt)
do
...
done

info1686 · 08-03-2009, 06:43 AM

Hi,
It helped

thanks a lot

ilikejam · 08-03-2009, 06:43 AM

If you're doing this for the scripting practice, then probably just ignore this...

$ nmap -sP -iL machines.txt

Dave