Control machine and check value

Shell Programming and Scripting
1

I'm thinking how to control and execute command to control my machine like update them,
scenario is creating a cron in machine 1 machine 2 machine 3 which download .txt file from core machine,
this txt file contain update function like:

kernel=1
yum=0
ssl=1

and store this file in /etc/update.txt

then this cron check if in update.txt file, kernel=1 then execute yum update kernel , if yum=1 then execute yum update and if ssl=0 do nothing,
is it possible (or any replacement idea)

how can i write check part, (if kernel = 1 then ... )

2

It you're running bash (or other recent shell), try

. /etc/update.txt
while IFS="=" read MOD REST; do echo -n "$MOD "; (( $MOD )) && echo update || echo keep; done < /etc/update.txt
kernel update
yum keep
ssl update

---------- Post updated at 17:21 ---------- Previous update was at 17:19 ----------

Or even just

while IFS="=" read MOD YESNO; do echo -n "$MOD "; (( $YESNO )) && echo update || echo keep; done < /etc/update.txt
3

can you explain how it work?
remember that i want to change update.txt file every week ,like set kernel=1 or 0 in certain time

4

Exactly. Change /etc/update.txt and run above; it will do what is requested. It reads the file line by line and executes a function or script if value equals 1. Above is a skeleton to show how it's doable; you'll need to define the actions yourself.

5 
export REMOTKERNEL=$( /usr/bin/curl -s  http://xxxx/kernel.txt )
export REMOTYUM=$( /usr/bin/curl -s  http://xxxx/yum.txt )
if [ $REMOTKERNEL == 0 ]; then
        echo "NO update"
else
        yum update kernel*
        echo "Upgrade completed"
fi
if [ $REMOTYUM == 0 ]; then
        echo "NO update"
else
        yum update -y
        echo "Upgrade completed"
fi

how about this function ?