AWK Linux shell variable calling a shell variable-CodePudding

this is probably an easy/what-the-hell-is-that question: here a blueprint of the script where I load 4 variables $1 $2 $3 and $4 in a function 'myloop' say

myloop () {
 echo col=$1 $2 $3 $4
 awk -v c1="$1" -v c2="$2" -F, 'BEGIN {
        FS=" ";
 }
 {
        xy =($c1*$c2);
 }
 END {
        print "Product" $3 "and " $4  #this is where $3 (='h2') and $4 (='02') don't print
        print "prod= " xy;
 }' file1 > res.txt
}
myloop 2 3 h2 o2

expected output in res.txt

product h2 and 02  
prod = 68

so as I said in the commented line in the code, I can't get to read $3 and $4.
I try passing $3 and $4 with
awk -v c1="$1" -v c2="$2" -vl1="$3" -v l2="$4" ... and then call $l1 and $l2 in the print statement but that does not work.
any hint would be appreciated as I'm no expert (as you can tell) in scripting
Thanks in advance

CodePudding user response：

$ cat tst.sh
#!/usr/bin/env bash

myloop() {
    echo "col=$*"
    awk -v c1="$1" -v c2="$2" -v l1="$3" -v l2="$4" '
        {
            xy  = $c1 * $c2
        }
        END {
            print "Product", l1, "and", l2
            print "prod =", xy 0
        }
    ' file1
}

myloop 2 3 h2 o2

$ ./tst.sh
col=2 3 h2 o2
Product h2 and o2
prod = 68

l1 and l2 are bad choices for variable names though since l looks far too much like 1 in many fonts and so obfuscates your code.

By the way, in your code in your question, this:

awk -F,

is changing FS from it's default value of a blank to a comma and then this:

BEGIN {
        FS=" ";
 }

is setting it back to the default blank value it had to begin with. Just don't do that.

CodePudding user response：

What you are looking for is called string interpolation and can be performed like so:

print "Product  ${3} and  ${4}"