How to make the variables of one script available for the other scripts?

Hello Everyone,

I want to know how can we make the variables of one script available for the other script?
for example i have three scripts variable_availability.sh,first.sh,second.sh and a file containing variables called common
----------------------------------

cat variable_availability.sh

#!/usr/local/bin/ksh
echo "starting the 1st script"
/root/Shell_Scripts/first.sh
echo "1st script finished"
echo "starting 2nd script"
/root/Shell_Scripts/second.sh
echo "2nd script finished"

--------------------------------

cat first.sh
#!/usr/local/bin/ksh
.  /root/Shell_Scripts/common
echo "The value of a=$a before modification"
a=`expr $a - 2`
echo "The value of a=$a after modification in 1st script"
echo "The value of b=$b before modification"
b=`expr $b + 2`
echo "The value of b=$b after modification in 1st script"

---------------------------------

cat second.sh
#!/usr/local/bin/ksh
.  /root/Shell_Scripts/common
echo "The value of a=$a in second script"
echo "the value of b=$b in second script"

----------------------------------------------

cat common

#!/usr/local/bin/ksh
a=10
b=20

--------------------------------------------
The output while running the variable_availability.sh script is as follows,
--------------------------------------------

starting the 1st script
The value of a=10 before modification
The value of a=8 after modification in 1st script
The value of b=20 before modification
The value of b=22 after modification in 1st script
1st script finished
starting 2nd script
The value of a=10 in second script
the value of b=20 in second script
2nd script finished

----------------------------------------------
The modified variables 'a' and 'b' in first.sh is not available for second.sh
Please share with me if anybody has any idea on this one.
Thanks in advance..........

You write desired "export VAR=VAL" into a temp file and execute "./temp" before "/root/Shell_Scripts/second.sh". In other way you can write "VAR=VAL" into temp file and execute ". temp" before "/root/Shell_Scripts/second.sh"

i tried as you said it's not working, i can't make those variables as global..cause the number of variable's are more.....

but the second method worked thanks....

---------- Post updated at 11:51 PM ---------- Previous update was at 11:40 PM ----------

I got it...
at the end of first.sh script
i wrote those variables to file called var_temp.sh and i included that one in the second script like this as follows,

cat second.sh

#!/usr/local/bin/ksh
. /root/Shell_Scripts/var_temp.sh
echo "The value of a=$a in second script"
echo "the value of b=$b in second script"

the output came in this way,

starting the 1st script
The value of a=10 before modification
The value of a=8 after modification in 1st script
The value of b=20 before modification
The value of b=22 after modification in 1st script
1st script finished
starting 2nd script
The value of a=8 in second script
the value of b=22 in second script
2nd script finished

Thanks sumitpandya...