Sstrhsrtj

I have an awk script in a bash script that I am starting to generalise.

I would like to put the string "$3" into a bash variable and use that variable in the awk script. This would allow me to easily update the script as needed.

For example:

NR > 1 && $3 != p { 

   #blah blah blah 

   printf("%s_%s%s", $3, header[i], OFS) 

}

would become something like

foo="$3"

NR > 1 && $foo != p { 

   #blah blah blah 

   printf("%s_%s%s", $foo, header[i], OFS) 

}

I've tried various combinations of foo="$3", ='$3', "$foo", '$foo', and ${foo} and can't get it to work.

What am I doing wrong?

.

I want to replace each instance of "$3" with "$foo" so that I only need to update $foo if I want to change the script.

The complete awk script inside the bash script:

#!/bin/bash



#these are bash variables

file=$1

header=$(head -n1 $file)





############################

# awk script               #

############################

read -d '' awkscript << 'EOF'

BEGIN { OFS = "\t" }



/^@/  {

   for (i = 1; i <= NF; ++i)

      header[i] = $i

   next

}



NR > 1 && $3 != p {

   #output two blank lines if needed

   if (print_blank) {

      print "\n"

   }

   print_blank = 1 



   for (i = 1; i <= 3; ++i)

      printf("%s%s", header[i], OFS)



   for (i = 4; i < NF; ++i)

      printf("%s_%s%s", $3, header[i], OFS)

   printf("%s_%s%s", $3, header[NF], ORS)

}



{ p=$3; print }

EOF



############################

# end awk script           #

############################



#blah

#blah

#blah



awk "$awkscript" ${tmp} > ${output}

You can inject a shell variable to your awk script with the -v option:

#!/bin/bash



#these are bash variables

file=$1

header=$(head -n1 $file)

awktoken=$2



############################

# awk script               #

############################

read -d '' awkscript << 'EOF'

BEGIN { OFS = "\t" }



/^@/  {

   for (i = 1; i <= NF; ++i)

      header[i] = $i

   next

}



NR > 1 && $variable != p {

   #output two blank lines if needed

   if (print_blank) {

      print "\n"

   }

   print_blank = 1 



   for (i = 1; i <= 3; ++i)

      printf("%s%s", header[i], OFS)



   for (i = 4; i < NF; ++i)

      printf("%s_%s%s", $variable, header[i], OFS)

   printf("%s_%s%s", $variable, header[NF], ORS)

}



{ p=$variable; print }

EOF



############################

# end awk script           #

############################



awk -vvariable="$awktoken" "$awkscript" ${tmp} > ${output}

variable is the name of the variable in this example. Normally you would call it without the $ but that is left in for it to expand to $3 or whatever number you choose