Why is sed not recognizing \t as a tab?

Question

sed \"s/\\(.*\\)/\\t\\1/\" $filename > $sedTmpFile && mv $sedTmpFile $filename

I am expecting this sed script to insert a <

Answer 1

sed doesn't support \t, nor other escape sequences like \n for that matter. The only way I've found to do it was to actually insert the tab character in the script using sed.

That said, you may want to consider using Perl or Python. Here's a short Python script I wrote that I use for all stream regex'ing:

#!/usr/bin/env python
import sys
import re

def main(args):
  if len(args) < 2:
    print >> sys.stderr, 'Usage:  '
    raise SystemExit

  p = re.compile(args[0], re.MULTILINE | re.DOTALL)
  s = sys.stdin.read()
  print p.sub(args[1], s),

if __name__ == '__main__':
  main(sys.argv[1:])