awk and Shell pass value to each other

Using variables from the shell in awk
One: "' $var '"
In this way, you don't have to change the habit of using the AWK program, which is commonly used by foreigners. Such as:
var= "Test"
awk ' begin{print ' $var ' "} '
This notation is actually a constant that is double-parenthesis into parentheses, passed to awk.
If the var contains spaces, for the shell not to use the space as a separator, it should be used as follows:
Var= "This is a test"
awk ' Begin{print ' "$var" ' "} '
Two: ' $var '
This is similar to the previous one. If the variable contains spaces, it becomes ' "" $var "" is more reliable.
Three: Export variable, use environ["var" form, get the value of environment variable
For example:
Var= "This is a test"; Export var;
awk ' Begin{print environ["var"]} '
Four: You can use awk's-v option (if the number of variables is not many, the individual favors this type of writing)
For example:
Var= "This is a test"
Awk-v awk_var= "$var" ' BEGIN {print Awk_var} '
This then passes the system variable var to the awk variable Awk_var.

awk passing values to shell variables
The idea of passing a variable from awk to the shell is simply to output several shell commands using awk (Sed/perl, and so on), and then use the shell to execute the commands.
Eval $ (awk ' begin{print ' var1= ' str1 '; var2= ' str2 ' "} ')
or eval $ (awk ' {printf ("var1=%s; var2=%s; var3=%s; ", $1,$2,$3)} ' Abc.txt)
Variables such as var1,var2 can then be used in the current shell.
echo "var1= $var 1-----var2= $var 2"