#!/bin/bash s='some query part....,MD5('"'"'$pass'"'"'),.....some query part some query part....,md5('"'"'$pass'"'"'),.....some query part' sed 's/\bmd5([^()]*)/sha1(&)/gI' <<< "$s"
Standard input is empty
some query part....,sha1(MD5('$pass')),.....some query part some query part....,sha1(md5('$pass')),.....some query part