On 10/27/2011 06:19 PM, Brian Cluff wrote:
> I've never had a need to do any bit twiddling in bash... thanks for this
> solution, It was very educational.
>
> Brian Cluff
>
> On 10/27/2011 11:43 AM, Dale Farnsworth wrote:
>> Larry wrote:
>>> I would like to apply a netmask to an arbitrary IP in a bash/dash script
>>> (e.g. apply 255.255.255.0 to 173.10.3.155 to get 173.10.3.0). Is
>>> there any
>>> easy way to do that without taking the IP apart, doing 4 operations and
>>> reassembling the results?
>>
>> I know you said without disassembly/reassembly, but here are some
>> bash functions that apply the mask using disassembly/reassembly.
>>
>> ===================== begin =======================
>> to_int()
>> {
>> # Convert from dotted-quad to integer
>> local i=$1
>> local OIFS="$IFS"
>> IFS=.
>> i=($i)
>> IFS="$OIFS"
>> echo $(((${i[0]}<< 24) + (${i[1]}<< 16) + (${i[2]}<< 8) +
>> ${i[3]}))
>> }
>>
>> to_ip()
>> {
>> # Covert from integer to dotted-quad
>> local d=$1
>> echo $(($d>> 24)).$(($d>> 16& 255)).$(($d>> 8& 255)).$(($d&255))
>> }
>>
>> and_ip()
>> {
>> # And two ip addresses in dotted-quad format
>> local ip1=$1
>> local ip2=$2
>> echo $(to_ip $(($(to_int $ip1)& $(to_int $ip2))))
>> }
>> ===================== end =======================
>>
>> Just pass the ip and netmask to and_ip:
>> Example:
>>
>> $ and_ip 11.22.33.44 255.255.255.0
>> 11.22.33.0
>>
>> -Dale
>> ---------------------------------------------------
>> PLUG-discuss mailing list -
PLUG-discuss@lists.plug.phoenix.az.us
>> To subscribe, unsubscribe, or to change your mail settings:
>>
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>>
>
> ---------------------------------------------------
> PLUG-discuss mailing list -
PLUG-discuss@lists.plug.phoenix.az.us
> To subscribe, unsubscribe, or to change your mail settings:
>
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss