Difference between bash-shell and ksh-shell by using while with read - what can I do in bash for the same response as in ksh?

Question

I have two scripts:

in bash

#!/bin/bash
H_VARIABLE=empty
echo "Zeile1
      Zeile2" |
while read satz
 do 
  H_VARIABLE="$H_VARIABLE $satz"
done
echo H_VARIABLE=$H_VARIABLE

Result:

H_VARIABLE=empty

in ksh

#!/usr/bin/ksh
H_VARIABLE=leer
echo "Zeile1
      Zeile2" |
while read satz
 do
  H_VARIABLE="$H_VARIABLE $satz"
done
echo H_VARIABLE=$H_VARIABLE

Result:

H_VARIABLE=leer Zeile1 Zeile2

Conclusion: leer Zeile1 Zeile2 != leer

What can I do in bash to get the same response as in ksh?

score 2 · Answer 1 · edited Apr 13 '17 at 12:37

The issue here is that, in bash, the while loop gets executed in a subshell when it is on the RHS of a pipe. You could do instead

H_VARIABLE=leer
while read satz
  do H_VARIABLE="$H_VARIABLE $satz"
done < <(
echo "Zeile1
      Zeile2"
)

using process substitution or, using a here string

H_VARIABLE=leer
while read satz
  do H_VARIABLE="$H_VARIABLE $satz"
done <<< "Zeile1
          Zeile2"

1 Answers1