grep searches a file for a given pattern.  Execute by
        grep [flags] regular_expression file_list

Flags are single characters preceeded by '-':
   -c      Only a count of matching lines is printed
   -f      Print file name for matching lines switch, see below
   -n      Each line is preceeded by its line number
   -v      Only print non-matching lines

On RSX, RT11, RSTS, input or output may be redirected:
        grep ... <file.in >file.out
The file_list is a list of files (wildcards are acceptable on RSX modes).
If no files are given, input comes from the terminal.  There is no prompting.
The file name is normally printed if there is a file given.
The -f flag reverses this action (print name no file, not if more).

The regular_expression defines the pattern to search for.  Upper- and
lower-case are always ignored.  Blank lines never match.  The expression
should be quoted to prevent file-name translation.
x	An ordinary character (not mentioned below) matches that character.
'\'	The backslash quotes any character.  "\$" matches a dollar-sign.
'^'	A circumflex at the beginning of an expression matches the
	  beginning of a line.
'$'	A dollar-sign at the end of an expression matches the end of
	  a line.
'.'	A period matches any character except "new-line".
':a'	A colon matches a class of characters described by the following
':d'	  character.  ":a" matches any alphabetic, ":d" matches digits,
':n'	  ":n" matches alphanumerics, ": " matches spaces, tabs, and
': '	  other control characters, such as new-line.
'*'	An expression followed by an asterisk matches zero or more
	  occurrances of that expression: "fo*" matches "f", "fo"
	  "foo", etc.
'+'	An expression followed by a plus sign matches one or more
	  occurrances of that expression: "fo+" matches "fo", etc.
'-'	An expression followed by a minus sign optionally matches
	  the expression.
'[]'	A string enclosed in square brackets matches any character in
	  that string, but no others.  If the first character in the
	  string is a circumflex, the expression matches any character
	  except "new-line" and the characters in the string.  For
	  example, "[xyz]" matches "xx" and "zyx", while "[^xyz]"
	  matches "abc" but not "axb".  A range of characters may be
	  specified by two characters seperated by "-".  Note that,
	  [a-z] matches alphabetics, while [z-a] never matches.

The concatenation of regular expressions is a regular expression.

