How to use variables in awk scripts - awk

Question

I am having trouble in using variables in awk scripts.
myvariable = tolower(substr($1,0,2)) tolower(substr($2,0,8))
so I can use $myvariable in the script instead of using the above every time.
I have tried ,but it prints everything nothing cut from the strings.
Thanks.

Answer 1

Awk is different from linux shell scripting.. you don't need to use "$" in front of variable names. In awk, "$" is special in its own way, for example it is used to reference a field/line/record.
if you declaring your variable declare it like this
myvariable = tolower(substr($1,0,2)) tolower(substr($2,0,8))
that is, drop the $ in front of your awk variable inside your awk statement
if you have a variable declare in your linux shell and you want to use that variable in your awk script
You can assign your shell variable to awk like
awk -v awkvariable="$myshellvariable" '{...commands....}'

Answer 2

AWK have three "types" of variables:
one for accessing fields ($1, $2, $3, ...)
a bunch of system variables (NR, NF, FS, RS, ...)
user-defined variables (my_var = 123, i = "hello", ...)
To print the lower to you simply write the variable name:
my_var = "john doe";
print my_var;
print NF; // Print Number of Fields
eg
echo john was here | awk '{print NF}' # 3
The interesting part is that you can mix system/user-defined variables with field variables ($1, ...) like so:
my_var = 2;
print $my_var; # print second field
print $NF; # Print last field (Using the "Number of Fields" variable)
eg
echo john was here | awk '{print $NF}' # here
echo john was here | awk '{print $(NF-1)}' # was