ksh88 changing single quotes to double quotes inside heredocs?

Question

I seem to be running into an issue that\'s specific to ksh88 that\'s changing single quotes to double quotes, but only under certain situations involving heredocs and comman

Answer 1

Here are my notes when I discovered this same bug several years ago.

Test script:

#!/bin/ksh
cat <<EOF
  $PWD "$PWD" '$PWD'
EOF
echo `cat <<EOF
  $PWD "$PWD" '$PWD'
EOF
`
echo $(cat <<EOF
  $PWD "$PWD" '$PWD'
EOF
)

Output for different shells:

• Linux KSH Version M 1993-12-28 q
• Linux Bash 3.00.15(1)

(NOTE: works as expected)

 /home/jrw32982 "/home/jrw32982" '/home/jrw32982'
 /home/jrw32982 "/home/jrw32982" '/home/jrw32982'
 /home/jrw32982 "/home/jrw32982" '/home/jrw32982'

• AIX Version M-11/16/88f
• Solaris Version M-11/16/88i

(NOTE: single quotes replaced with double quotes and variable not substituted)

 /home/jrw32982 "/home/jrw32982" '/home/jrw32982'
 /home/jrw32982 "/home/jrw32982" '/home/jrw32982'
 /home/jrw32982 "/home/jrw32982" "$PWD"

Work-around:

1. Compute the single-quoted string externally from the here-file

   abc=xyz
   STR="'$abc'"
   x=$( cat <<EOF
     $abc "$abc" $STR
   EOF
   )
   

2. Use the here-file in a function instead of directly

   fn() {
     cat <<EOF
       $abc "$abc" '$abc'
   EOF
   }
   abc=xyz
   x=$(fn)