Modifying a variable in another shell script - bash

Question

I am trying to modify the variables of one shell script, using another script. This is what I have so far:
script1.sh
#!/bin/bash
var=123.45.67.890
script2.sh
#!/bin/bash
currVar=000.00.00.000
. /./script1.sh
var=$currVar
I understand that I am not modifying Script 1 here, but simply temporarily modifying var. How can I modify this var in script 1, via script 2?
Solution
. /./script1.sh
echo $var | sed "s/$var/$currVar/g" /./script1.sh > "temp.txt" && mv temp.txt /./script1.sh

Answer 1

Just use sed in 2nd script (script2.sh) as
currVar="000.00.00.000"
sed -r -i.bak "s/var=([[:graph:]]+)/var=$currVar/" script1.sh
var=000.00.00.000
where [[:graph:]] is a character class for [[:alnum:]] & [[:punct:]] to match values for var with printable characters/meta-characters.
Since you mentioned it is a proper IP address, use a proper regEx as
sed -r "s/(\b[0-9]{1,3}\.){3}[0-9]{1,3}\b/$currVar/" script1.sh
var=000.00.00.000
(\b[0-9]{1,3}\.){3}[0-9]{1,3} implies match 3 groups consisting of digits from 0-9, which each group could have from 1-3 digits each, preceded by a dot . and the 4th group also the same as the last. Remember the each group I am mentioning represents an IP octet

Answer 2

Normally, variables in scripts have local scope. If you export the variable, you can extend this scope to include any child processes. However, it looks like you might want to use the modified value when script1.sh runs. If that is the case, you can use the new var value as an input to script1.sh when you run it.
if [[ -z "$1" ]];
then
var=$1
else
var=123.45.67.890
This will check if you gave any parameters when you ran script1.sh, and if you did, then it should set your var equal to this value instead of the default IP.