You cannot search ! directly because it puts process behind.
For instance, you cannot search ! in
How can you search ! in man?
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In less, when you press
? to search, a few characters have a special meaning if you type them at the beginning of the search expression. The exclamation mark is one of them. To avoid
! having a special meaning, put a backslash before it. It is very common for backslash to mean “interpret the next character literally”.
So to search for an exclamation mark, press