Here is a great little application that does a find and replace on a particular file, file type or file contents, then replaces it with a string of your choice. It can look in sub directories as well.
The small app is called FART, yes that’s right FART - Find And Replace Text!

Usage: FART [options] [--] 

Options

• -h, –help Show this help message (ignores other options)
• -q, –quiet Suppress output to stdio / stderr
• -V, –verbose Show more information
• -r, –recursive Process sub-folders recursively
• -c, –count Only show filenames, match counts and totals
• -i, –ignore-case Case insensitive text comparison
• -v, –invert Print lines NOT containing the find string
• -n, –line-number Print line number before each line (1-based)
• -w, –word Match whole word (uses C syntax, like grep)
• -f, –filename Find (and replace) filename instead of contents
• -B, –binary Also search (and replace) in binary files (CAUTION)
• -C, –c-style Allow C-style extended characters (\xFF\t\n\r\\ etc.)
• –cvs Skip cvs dirs; execute “cvs edit” before changing files
• –svn Skip svn dirs
• –remove Remove all occurences of the find_string
• -a, –adapt Adapt the case of replace_string to found string
• -b, –backup Make a backup of each changed file
• -p, –preview Do not change the files but print the changes

Example 1 (replace text, preview only)

fart -c -r -i -p *.txt original_text new_text

This will look for all .txt files in a sub directory, locate the original_text string within the .txt file and change it to new_text. The -p switch means it won't actually change anything because this is a preview, showing you how many strings it found within each .txt file.

Example 2 (replace text)

fart -c -r -i *.txt original_text new_text

Same as above except it will do the actual replacement.

Example 3 (remove text)

fart -r -i --remove *.txt "remove this text"

Rather than replacing one term for another this will remove the specified term.

NOTE: Use quotes around text if it contains spaces, tabs, etc.

Download FART from SourceForge.