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Full Discussion: Script error with when input is empty
Top Forums Shell Programming and Scripting Script error with when input is empty Post 302302685 by cfajohnson on Tuesday 31st of March 2009 04:05:42 PM
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

 

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LEARN ABOUT POSIX

innetgr

innetgr(1)							   NSS utilities							innetgr(1)

NAME

       innetgr - Check netgroup membership

SYNTAX

       innetgr [-d domain] [-h host] [-u user] [-v] <netgroup>

DESCRIPTION

       innetgr	checks if the specified user, host or domain is a member of the given netgroup. The program does not produce any output unless the
       verbose ( -v ) flag is given.

       The exit status is 0 if the user/host/doman combination is a member of the given netgroup.  Exit status is 1  if  the  combination  is  not
       found in the group, and 2 if one of the arguments are invalid.

OPTIONS

       --domain <domain> | -d <domain>
	      Search in the given domain.

       --host <host name> | -h <host name>
	      Search for the given host name.

       --user <user name> | -u <user name>
	      Search for the given user name.

       --verbose | -v
	      Enable verbose mode

       --version | -V
	      Show version information.

EXAMPLES

       To check if the current host is listed in the netgroup allhosts, use this command line:

       if innetgr -h `uname -n` allhosts ; then echo "Found"; fi

CONFORMING TO

       A innetgr program first appeared in NetBSD 1.4.

AUTHORS

       Petter Reinholdtsen <pere@hungry.com>

SEE ALSO

       getent(1) netgroup(1) innetgr(3) netgroup(5) nsswitch.conf(5)

Petter Reinholdtsen							0.7								innetgr(1)
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