I have a plain text document, which I want to compile inside LaTeX. However, sometimes it has the characters, \"#\", \"$\", \"%\", \"&\", and \"_\". To compile properly
I do not respond for sed, the other answers are good enougth ;-)
You can use less as viewer to check your huge file (or more, but less is more comfortable than more).
For searching, you can use fgrep: it ignores regular expression => fgrep '\$' will really search for text \$. fgrep is the same as invoking grep -F.
EDIT:
fgrep '\$' and fgrep "\$" are different. In the second case, bash interprets the string and will replace it by a single character: $ (i.e. fgrep will search for $ only).