Optimize shell script for multiple sed replacements

Question

I have a file containing a list of replacement pairs (about 100 of them) which are used by sed to replace strings in files.

The pairs go like:

Answer 1

{ cat replacement_list;echo "-End-"; cat YourFile; } | sed -n '1,/-End-/ s/$/³/;1h;1!H;$ {g
t again
:again
   /^-End-³\n/ {s///;b done
      }
   s/^\([^|]*\)|\([^³]*\)³\(\n\)\(.*\)\1/\1|\2³\3\4\2/
   t again
   s/^[^³]*³\n//
   t again
:done
  p
  }'

More for fun to code via sed. Try maybe for a time perfomance because this start only 1 sed that is recursif.

for posix sed (so --posix with GNU sed)

explaination

• copy replacement list in front of file content with a delimiter (for line with ³ and for list with -End-) for an easier sed handling (hard to use \n in class character in posix sed.
• place all line in buffer (add the delimiter of line for replacement list and -End- before)
• if this is -End-³, remove the line and go to final print
• replace each first pattern (group 1) found in text by second patttern (group 2)
• if found, restart (t again)
• remove first line
• restart process (t again). T is needed because b does not reset the test and next t is always true.