#!/bin/bash # ideone boilerplate: run in temp dir t=$(mktemp -d -t ideone.XXXXXXXX) || exit trap 'rm -rf "$t"' ERR EXIT cd "$t" cat <<\: >input.txt there is a foo in your bar : cat <<\: >test.txt

PLACE_HOLDER

: sed 's/\&/\\&/g 1s/^/s\&PLACE_HOLDER\&/ $!s/$/\\/ $s/$/\&/' input.txt echo ---------- sed 's/\&/\\&/g 1s/^/s\&PLACE_HOLDER\&/ $!s/$/\\/ $s/$/\&/' input.txt | sed -f - test.txt