Which of the following statements is not true regarding the grep filter?

It is used to seach a file for a particular pattern of characters and displays all lines that contain that pattern.

The pattern that is searched for in the file is referred to as the regular expression.

grep can be used without specifying a regular expression.

The filenames are optional.In this case grep expects standard input.

The -c option prints only a count of the lines that match the pattern.

Answer:
grep can be used without specifying a regular expression.

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