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Script error with when input is empty

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# 1  
Old 03-31-2009
Data Script error with when input is empty
Hi,

I created the following shell script to lookup multiple name servers for a domain.

Code:
#!/bin/bash

echo -n "Enter the domain name and press [ENTER]: "
read domain


result1=`dig +short $domain @4.2.2.1`
revresult1=`host $result1 | cut -f5 -d " "`

echo "test1"

result2=`dig +short $domain @dns1.vistapages.com`
revresult2=`host $result2 | cut -f5 -d " "`

echo "test2"

result3=`dig +short $domain @dns2.vistapages.com`
revresult3=`host $result3 | cut -f5 -d " "`



echo "test3"
result4=`dig +short $domain @ns1.hostmds.com`
revresult4=`host $result4 | cut -f5 -d " "`

echo "test4"
result5=`dig +short $domain @ns1.hostmds.com`
revresult5=`host $result5 | cut -f5 -d " "`

echo "test5"
result6=`dig +short $domain @dns1.hostingplex.com`
revresult6=`host $result6`

echo "test6"
result7=`dig +short $domain @dns2.hostingplex.com`
revresult7=`host $result7`

echo "test7"
echo "================================="

echo " Result at Verizon DNS : $result1"
echo " Reverse at Verizon DNS : $revresult1"

echo "================================="
echo " Result at dns1.vistapages.com  : $result2"
echo " Reverse at dns1.vistapages.com : $revresult2"
echo "================================="

echo " Result at dns2.vistapages.com : $result3"
echo " Reverse at dns2.vistapages.com : $revresult3"

echo "================================="

echo " Result at ns1.hostmds.com : $result4"
echo " Reverse at ns1.hostmds.com : $revresult4"

echo "================================="
echo " Result at ns2.hostmds.com : $result5"
echo " Reverse at ns2.hostmds.com : $revresult5"

echo "================================="

echo " Result at dns1.hostingplex.com : $result6"
echo " Reverse at dns1.hostingplex.com  : $revresult6"
echo "================================="


echo " Result at dns2.hostingplex.com : $result7"
echo " Reverse at dns2.hostingplex.com : $revresult1"

But when the dns server do not have any result the script generates error.

Code:
Enter the domain name and press [ENTER]: test.com
test1
Usage: host [-aCdlriTwv] [-c class] [-N ndots] [-t type] [-W time]
            [-R number] hostname [server]
       -a is equivalent to -v -t *
       -c specifies query class for non-IN data
       -C compares SOA records on authoritative nameservers
       -d is equivalent to -v
       -l lists all hosts in a domain, using AXFR
       -i IP6.INT reverse lookups
       -N changes the number of dots allowed before root lookup is done
       -r disables recursive processing
       -R specifies number of retries for UDP packets
       -t specifies the query type
       -T enables TCP/IP mode
       -v enables verbose output
       -w specifies to wait forever for a reply
       -W specifies how long to wait for a reply
       -4 use IPv4 query transport only
       -6 use IPv6 query transport only
       -s a SERVFAIL response should stop query
test2
Usage: host [-aCdlriTwv] [-c class] [-N ndots] [-t type] [-W time]
            [-R number] hostname [server]
       -a is equivalent to -v -t *
       -c specifies query class for non-IN data
       -C compares SOA records on authoritative nameservers
       -d is equivalent to -v
       -l lists all hosts in a domain, using AXFR
       -i IP6.INT reverse lookups
       -N changes the number of dots allowed before root lookup is done
       -r disables recursive processing
       -R specifies number of retries for UDP packets
       -t specifies the query type
       -T enables TCP/IP mode
       -v enables verbose output
       -w specifies to wait forever for a reply
       -W specifies how long to wait for a reply
       -4 use IPv4 query transport only
       -6 use IPv6 query transport only
       -s a SERVFAIL response should stop query
test3
Usage: host [-aCdlriTwv] [-c class] [-N ndots] [-t type] [-W time]
            [-R number] hostname [server]
       -a is equivalent to -v -t *
       -c specifies query class for non-IN data
       -C compares SOA records on authoritative nameservers
       -d is equivalent to -v
       -l lists all hosts in a domain, using AXFR
       -i IP6.INT reverse lookups
       -N changes the number of dots allowed before root lookup is done
       -r disables recursive processing
       -R specifies number of retries for UDP packets
       -t specifies the query type
       -T enables TCP/IP mode
       -v enables verbose output
       -w specifies to wait forever for a reply
       -W specifies how long to wait for a reply
       -4 use IPv4 query transport only
       -6 use IPv6 query transport only
       -s a SERVFAIL response should stop query
test4
Usage: host [-aCdlriTwv] [-c class] [-N ndots] [-t type] [-W time]
            [-R number] hostname [server]
       -a is equivalent to -v -t *
       -c specifies query class for non-IN data
       -C compares SOA records on authoritative nameservers
       -d is equivalent to -v
       -l lists all hosts in a domain, using AXFR
       -i IP6.INT reverse lookups
       -N changes the number of dots allowed before root lookup is done
       -r disables recursive processing
       -R specifies number of retries for UDP packets
       -t specifies the query type
       -T enables TCP/IP mode
       -v enables verbose output
       -w specifies to wait forever for a reply
       -W specifies how long to wait for a reply
       -4 use IPv4 query transport only
       -6 use IPv6 query transport only
       -s a SERVFAIL response should stop query
test5
test6
test7
=================================
 Result at Verizon DNS : 205.178.152.103
 Reverse at Verizon DNS : w2k3-cfm3.prod.netsolhost.com.
=================================
 Result at dns1.vistapages.com  : 
 Reverse at dns1.vistapages.com : 
=================================
 Result at dns2.vistapages.com : 
 Reverse at dns2.vistapages.com : 
=================================
 Result at ns1.hostmds.com : 
 Reverse at ns1.hostmds.com : 
=================================
 Result at ns2.hostmds.com : 
 Reverse at ns2.hostmds.com : 
=================================
 Result at dns1.hostingplex.com : 208.83.209.12
 Reverse at dns1.hostingplex.com  : 12.209.83.208.in-addr.arpa domain name pointer 208-83-209-12.mdswireless.com.
=================================
 Result at dns2.hostingplex.com : 208.83.209.12
 Reverse at dns2.hostingplex.com : w2k3-cfm3.prod.netsolhost.com.

How can I get rid of these errors.
# 2  
Old 03-31-2009
Quote:
Originally Posted by mohitmoudgil
Hi,

I created the following shell script to lookup multiple name servers for a domain.

Code:
#!/bin/bash

echo -n "Enter the domain name and press [ENTER]: "
read domain


result1=`dig +short $domain @4.2.2.1`
revresult1=`host $result1 | cut -f5 -d " "`

How can I get rid of these errors.

Check whether the command was successful:

Code:
if result1=`dig +short $domain @4.2.2.1`
then
   revresult1=`host $result1 | cut -f5 -d " "`
fi

Or check for content in the variable:

Code:
result1=`dig +short $domain @4.2.2.1`
if [ -n "$result1" ]
then
   revresult1=`host $result1 | cut -f5 -d " "`
fi

# 3  
Old 03-31-2009
Hi,

Thank you very much!! You got it working.
Code:
#!/bin/bash

result1="NULL"
result2="NULL"
result3="NULL"
result4="NULL"
result5="NULL"
result6="NULL"
result7="NULL"

revresult1="NULL"
revresult2="NULL"
revresult3="NULL"
revresult4="NULL"
revresult5="NULL"
revresult6="NULL"
revresult7="NULL"


echo -n "Enter the domain name and press [ENTER]: "
read domain


result1=`dig +short $domain @4.2.2.1`

if [ -n "$result1" ]
then

revresult1=`host $result1 | cut -f5 -d " "`

fi


result2=`dig +short $domain @dns1.vistapages.com`

if [ -n "$result2" ]
then

revresult2=`host $result2 | cut -f5 -d " "`
fi



result3=`dig +short $domain @dns2.vistapages.com`

if [ -n "$result3" ]
then

revresult3=`host $result3 | cut -f5 -d " "`

fi


result4=`dig +short $domain @ns1.hostmds.com`


if [ -n "$result4" ]
then
revresult4=`host $result4 | cut -f5 -d " "`
fi


result5=`dig +short $domain @ns1.hostmds.com`
if [ -n "$result5" ]
then

revresult5=`host $result5 | cut -f5 -d " "`
fi


result6=`dig +short $domain @dns1.hostingplex.com`

if [ -n "$result6" ]
then
revresult6=`host $result6`
fi



result7=`dig +short $domain @dns2.hostingplex.com`
if [ -n "$result7" ]
then

revresult7=`host $result7`
fi





echo "================================="

echo " Result at Verizon DNS : $result1"
echo " Reverse at Verizon DNS : $revresult1"

echo "================================="
echo " Result at dns1.vistapages.com  : $result2"
echo " Reverse at dns1.vistapages.com : $revresult2"
echo "================================="

echo " Result at dns2.vistapages.com : $result3"
echo " Reverse at dns2.vistapages.com : $revresult3"

echo "================================="

echo " Result at ns1.hostmds.com : $result4"
echo " Reverse at ns1.hostmds.com : $revresult4"

echo "================================="
echo " Result at ns2.hostmds.com : $result5"
echo " Reverse at ns2.hostmds.com : $revresult5"

echo "================================="

echo " Result at dns1.hostingplex.com : $result6"
echo " Reverse at dns1.hostingplex.com  : $revresult6"
echo "================================="


echo " Result at dns2.hostingplex.com : $result7"
echo " Reverse at dns2.hostingplex.com : $revresult1"

Now I want the domain input should be taken from a webpage like a text field, not the command line.

Can you please help me in that.
# 4  
Old 03-31-2009
Hi,

I could execute the script on webpage by hardcoding the domain name

http://mohitmoudgil.com/cgi-bin/test2.sh

but how can I take the value on the web page itself.
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