Shell Programming and Scripting

ID|NAME|AGE|GENDER
10|ABC|30|M
20|DEF|20|F

echo -n '10,abc'|md5sum =hashvalue

ID|NAME|AGE|GENDER|HASHEDCOLUMNS|HASHVALUE
10|abc|30|M|ID,NAME|hashvalue
20|def|20|F|ID,NAME|hashvalue

ID|NAME|AGE|GENDER|HASHEDCOLUMNS|HASHVALUE
10|abc|30|M|ID,gender|hashvalue
20|def|20|F|ID,gender|hashvalue

#!/usr/bin/sh

target="id"   # here i m passing the header column to be md5 applied ideally this is parameterized and can send more than one column name seperated by comma "
target_idx=   # the column number of that field

{
  # reading header.
  IFS=, read -r -a header
  for idx in "${!header[@]}"; do  # and look for the target field in it
    [[ ${header[$idx]} = $target ]] && { target_idx=$idx; break; }
  done
  # then, iterate over lines
  while IFS=, read -r -a line; do
    a=echo-n ${line[$target_idx]}|md5sum # if my input in target is "id"
  done
} <testfile.txt

echo$line|"$a"