The magical, mystical FOG post download script

[dburk]

@george1421 Update to part 5 Access FOG host data

if [[ ! -z $mac ]]; then
    curl -A "" -Lkso /tmp/hinfo.sh ${web}/service/hostinfo.php -d "mac=$mac" 
    if [[ -f /tmp/hinfo.sh ]]; then
        . /tmp/hinfo.sh
    fi
fi

[george1421]

@dburk Great catch, thank you for the update. I’m not sure how I missed that one but great job. I’ll get my post updated so that it works correctly.

[enswafford]

I am confused about the actual syntax of this post download script.
In the sample script on the FOG server, it says:
“# syntax of the post download scripts are”
"#. ${postdownpath}<SCRIPTNAME>

(assuming the script is called (without quotes) “mypostdlscript.sh”, and it is in “/images/postinstall/” directory)
Should I be typing (without quotes) “. ${postdownpath}mypostdlscript.sh”
or should I be typing it as (again without quotes) “. /images/postinstall/mypostdlscript.sh”?
Can you explain what the ${postdownpath} means?

[Sebastian Roth]

@enswafford said in The magical, mystical FOG post download script:

${postdownpath}

This is a variable in bash scripts. Should probably be set to /images/postdownloadscripts/

[george1421]

@enswafford said in The magical, mystical FOG post download script:
“. ${postdownpath}mypostdlscript.sh”
First of all sebasian is spot on with this explanation.

To break this post download script a bit more. The script is actually a bash shell script. Its akin to a DOS batch file, with 1000’s more capability. The bash variable is called postdownpath so the bash shell interpreter understands its a variable you prefix the variable name with a dollar sign. The interpreter can still get a bit confused at times so you wrap the variable with curly braces so it knows fore sure there is a variable call ${postdownpath} . The FOG server populates that variable before the post install script runs with the proper value so you don’t need to know where the post install scripts are run from.

So the command is this “. ${postdownpath}mypostdlscript.sh” The preceding dot is shorthand way of saying run the mypostdlscript.sh in this context so all of my populated variables are shared with this new bash script. Its a little complicated to explain but that is what that entire command will do. So if you set a variable in the current script, that variable will be available to any subsequent bash scripts you create.

[Tom Elliott]

@george1421 I need to add,

the preceeding . is NOT just a way of saying run, it’s also a shorthand way of sourcing the file, the same as:

source mypostdlscript.sh

Basically, source means to bring the file in, similar to requiring other files in order to access different variables/functions that you may want separated from the purpose of the main running script.

[zaboxmaster]

@george1421 Looking at the code, say if I wanted to extract the hostimageid and assign it to $imageid in a while loop, would the following be correct :

while [[ $imageid -le 10 ]]; do
    if [[ -z "imageid"]]; then
        if [[ ! -z $mac ]]; then
            curl -A "" -Lkso /tmp/hinfo.sh ${web}/fog/service/hinfo.php -d "mac=$mac&hostimageid=$imageid"
            if [[ -f /tmp/hinfo.sh ]]; then
                . /tmp/hinfo.sh
            fi
            echo "Please wait"
            sleep 60
        fi
done

This should in theory run the while loop until a value is given to the $imageid

[george1421]

@zaboxmaster said in The magical, mystical FOG post download script:

curl -A “” -Lkso /tmp/hinfo.sh ${web}/fog/service/hinfo.php -d “mac=$mac&hostimageid=$imageid”

That call returns all variables not just the one you pass to it. Only the mac address value is used and understood.

[Tom Elliott]

@zaboxmaster I’ve updated your code into a code block so you can see a bit cleaner on what’s happening.

First, the loop you’re providing will not work. This is because it’s missing a fi (for the if [[ -z "imageid" ]] line).

Second: Why is the code looking if the value is less than or equal to 10? Why do you need to loop this code at all?

From what I understand of your needs, you want to get the image ID for a host if the host has no image id set. This makes 0 sense. In what scenario would you be able to get an image ID for a host that has no assigned image ID? This is circular referencing as no matter what happens, the host isn’t going to have an image id associated to it. So it will never be able to complete the loop.

You seem to be rebuilding the cart before you have built it. (I don’t know if the metaphor makes sense here.)

Too me, what you’re looking for seems rather strange. You would never be able to image a host if you don’t have an image assigned (and did not select an image during pxe boot.)

If this is during registration, what’s the point in this?

1. The host doesn’t exist, so calling hinfo.sh will gain you nothing.
2. You have to be in front of the host when registering (unless you are using quick reg - in which case why not set the quick reg image id for quick registration rather than re-invent the wheel) so why try an automate this part?
3. Why all the erroneous checking in the first place? First, your while loop is extremely limiting. You have it set to check if the imageid is less than or equal to 10. What about image id 1? Why is this a valid check on anything?
4. In side the while loop you have if [[ -z "$imageid" ]]; then Why not just make the while loop while [[ -z $imageid && $imageid -gt 0 ]]; do
5. In what scenario would you ever be able to do anything on a machine with the mac variable is not set (you should not need to check this variable as FOS kind of relies on it in the first place)?
6. Why are you waiting for a minute to do anything?

If there’s a valid reasoning for this I would redo the script to run:

while [[ -z $imageid && $imageid -gt 0 ]]; do
    curl -A "" -Lkso /tmp/hinfo.sh ${web}/fog/service/hinfo.php -d "mac=$mac"
    if [[ -f /tmp/hinfo.sh ]]; then
        . /tmp/hinfo.sh
    fi
    echo "Please wait"
    sleep 60
done

[zaboxmaster]

@Tom-Elliott Thank you for your input. I realize that i have made a mistake in the code. I am new to bash and fog in general.

The idea is to have a while loop running until an image has been assigned. Or a sort of pause before it continues. The reason being that this is being done remotely and I would be assigning the correct image to the host. I am not psychically in front of the computer. The hosts users would only select that they want an image to be deployed and not select an image to deploy.

Hope that makes sense.

So what I guess I was looking for and I do realize that this is n the wrong thread is a way inside a while loop to see if an image has been assigned before continuing on with the deployment. BTW I have modified the fog.man.reg to go straight to the fog.download and the end of the registration.