How to deal with assigning variables as below? I am assigning value var1=1 next assigning var2=$var1, but every time I change value of var1, echo $var2 shows always old value i.e
# var1=1 # var2=$var1 # echo $var2 1 # var1=2 # echo $var2 1 This is a common miss-conception about how many/most programming languages work.
In imperative languages (bash/C/Java/python....), the = operator does not work the same way as in maths.
a=1 means put 1 into a (overwriting what was there).
I.E.
var1=1 # var1 ← 1 #overwrite var1 with 1 var2=$var1 # var2 ← $var1 #overwrite var2 with evaluation of $var1 (i.e 1) var1=2 # var1 ← 2 #overwrite var1 with 2 stdout ←← $var2 #append $var2 to stdout Therefore
# var1 var2 var1=1 # 1 n/a var2=$var1 # 1 1 var1=2 # 2 1 If you assign the value of var1 to var2 you have two independent variables var1 and var2 which just happen to have the same values.
You could use a variable var2 declared with the nameref attribute for a reference to var1.
$ var1=1 $ declare -n var2=var1 $ echo "$var2" 1 $ var1=2 $ echo "$var2" 2 $ var2=3 $ echo "$var2 $var1" 3 3 