Awk cross reference code not working on different platform - bash

Question

I have a cross reference bash script using awk, however it works on my laptop but doesn't work on my other computer :s..
script example is :
"C:\cygwin\bin\gawk.exe" -F: "FNR==NR{a[$2]=$1;next} $1 in a{print a[$1] FS $2}" username.email.txt email.phone.txt > username.phone.txt
username.email input:
example:email#email.com
email.phone.txt input:
email#email.com:0123456789
username.phone output:
example:0123456789
so what happens here is if email is in > email.phone.txt, output > username & phone in username.phone.txt cross referencing between the 3 files.
this works fine on another laptop, however doesn't work on another computer.. i get a syntax error & invalid subscript expression.
Example of error:
gawk: cmd. line:1: FNR==NR{a[]=;next} in a{print a[] FS }
gawk: cmd. line:1: ^ syntax error
gawk: cmd. line:1: error: invalid subscript expression
gawk: cmd. line:1: FNR==NR{a[]=;next} in a{print a[] FS }
gawk: cmd. line:1: ^ syntax error
gawk: cmd. line:1: FNR==NR{a[]=;next} in a{print a[] FS }
gawk: cmd. line:1: ^ syntax error
gawk: cmd. line:1: FNR==NR{a[]=;next} in a{print a[] FS }
gawk: cmd. line:1: ^ syntax error
gawk: cmd. line:1: error: invalid subscript expression

Answer 1

Why use double-quotes for the body of awk commands? $1 has a special meaning when double-quoted, the values of $1 are being evaluated as positional arguments and are passed to awk, since they don't have values for it, that is why they are empty. Since awk sees an empty subscript array it complains it is not a valid array.
Simply single-quote it to solve the problem.
"C:\cygwin\bin\gawk.exe" -F: 'FNR==NR{a[$2]=$1;next} $1 in a{print a[$1] FS $2}' username.email.txt email.phone.txt > username.phone.txt
In general we single-quote the action(s) part to awk to pass them as literal strings to not let the shell do its parsing before passing it to awk. As mentioned single-quotes pass the string as-is without going through any expansion.
If you still want to go through the pain of using double-quotes, escape the dollar sign to deprive of its special meaning i.e. with an escaped character the dollar variables do not go through expansion ( not recommended in any way)
"C:\cygwin\bin\gawk.exe" -F: "FNR==NR{a[\$2]=\$1;next} \$1 in a{print a[\$1] FS \$2}" username.email.txt email.phone.txt > username.phone.txt