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nicolasdiogo

09-16-2012 07:00 AM

creating VLAN setup script - help needed

hello

i am trying to create a script that will setup 3 VLANs
i have tried to create a script (below) it fails miserably.

if somebody could provide me with suggestion on how to correct it ..

thanks,

Code:

#! /bin/bash



#

# SETTING UP CONNECTION TO DEVELOPMENT ENVIRONMENT



export ADAPTER=$1



#

# if there is no input - set it to the default 'eth0'

if[[ $ADAPTER ]] && export ADAPTER=eth0





# set VLAN 21

if [[ ! $( ifconfig $ADAPTER.21 | grep $ADAPTER.21 ) ]] 

then 

        vconfig add $ADAPTER 21

fi



sh $(ip addr add 192.168.21.19/24 dev $ADAPTER.21)





# set VLAN 201

if [[ ! $( ifconfig $ADAPTER.201 | grep $ADAPTER.201 ) ]] 

then

        vconfig add $ADAPTER 201

fi

sh $(ip addr add 192.168.201.19/24 dev $ADAPTER.201)





# set VLAN 202

if [[ ! $( ifconfig $ADAPTER.202 | grep $ADAPTER.202 ) ]] 

then

        vconfig add $ADAPTER 202

fi



sh $(ip addr add 192.168.202.19/24 dev $ADAPTER.202)

Ser Olmy

09-16-2012 08:38 AM

It would help a lot if you could be a bit more specific as to what isn't working, and what error messages you're getting, if any.

I can see at least two problems with your script:

You're running ip by spawning instances of sh (why?) that won't return control to your script
Your adding VLANs with vconfig without checking whether VLANs are supported by the kernel (you may have to load the 802.1q VLAN module with modprobe 8021q)

nicolasdiogo

09-16-2012 10:09 AM

thanks

since i running this script on installation that i control.
i did not think about testing for the module.

but i do not understand what you meant by 'running ip by spawning instances of sh (why?) that won't return control to your script'

- what would be your suggestion to do this properly??

Ser Olmy

09-16-2012 11:25 AM

Quote:

Originally Posted by nicolasdiogo (Post 4781648)

but i do not understand what you meant by 'running ip by spawning instances of sh (why?) that won't return control to your script'

- what would be your suggestion to do this properly??

Well, you're doing this:

Code:

sh $(ip addr add 192.168.21.19/24 dev $ADAPTER.21)

That starts a new instance of the shell (sh) and runs the ip command. Unfortunately, the new shell instance will stick around until someone types "exit".

Instead, you could simply do this:

Code:

ip addr add 192.168.21.19/24 dev $ADAPTER.21

nicolasdiogo

09-16-2012 11:53 AM

thanks a lot for that!!

i was getting these 'hangs' without understanding why; and now i know

another problem that i find if the check to see the interface already exists.
i try

Code:

if [ ! -z "$( ifconfig $ADAPTER.21 | grep -i "link" )" ] ;

then

    vconfig add $ADAPTER 21

    ip addr add 192.168.21.19/24 dev $ADAPTER.21

fi

which works find when there is an interface running - but it fails first time as the interface is not valid and 'ifconfig' issues and error message.

any suggestion on that?

thanks,

Ser Olmy

09-16-2012 12:56 PM

Quote:

Originally Posted by nicolasdiogo (Post 4781694)

another problem that i find if the check to see the interface already exists.
i try

Code:

if [ ! -z "$( ifconfig $ADAPTER.21 | grep -i "link" )" ] ;

then

    vconfig add $ADAPTER 21

    ip addr add 192.168.21.19/24 dev $ADAPTER.21

fi

which works find when there is an interface running - but it fails first time as the interface is not valid and 'ifconfig' issues and error message.

If you're thinking of the ifconfig command in the if test, there's really nothing really wrong about that. You're checking to see if the interface exists, and if it doesn't, ifconfig will complain. You can redirect stderr to /dev/null to hide the error message:

Code:

if [ ! -z "$( ifconfig $ADAPTER.21 2>/dev/null | grep -i "link" )" ] ;

nicolasdiogo

09-25-2012 03:37 PM

thanks Ser Olmy for helping me out with this script

and for also teaching me a couple of things along the way.

with regards,

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