GREP(1) 						      General Commands Manual							   GREP(1)

NAME

       grep, egrep, fgrep - search a file for a pattern

SYNOPSIS

       grep [ option ] ...  expression [ file ] ...

       egrep [ option ] ...  [ expression ] [ file ] ...

       fgrep [ option ] ...  [ strings ] [ file ]

DESCRIPTION

       Commands  of  the  grep	family search the input files (standard input default) for lines matching a pattern.  Normally, each line found is
       copied to the standard output; unless the -h flag is used, the file name is shown if there is more than one input file.

       Grep patterns are limited regular expressions in the style of ed(1); it uses a compact nondeterministic algorithm.  Egrep patterns are full
       regular	expressions;  it uses a fast deterministic algorithm that sometimes needs exponential space.  Fgrep patterns are fixed strings; it
       is fast and compact.

       The following options are recognized.

       -v     All lines but those matching are printed.

       -c     Only a count of matching lines is printed.

       -l     The names of files with matching lines are listed (once) separated by newlines.

       -n     Each line is preceded by its line number in the file.

       -b     Each line is preceded by the block number on which it was found.	This is sometimes useful in locating disk block  numbers  by  con-
	      text.

       -s     No output is produced, only status.

       -h     Do not print filename headers with output lines.

       -y     Lower case letters in the pattern will also match upper case letters in the input (grep only).

       -e expression
	      Same as a simple expression argument, but useful when the expression begins with a -.

       -f file
	      The regular expression (egrep) or string list (fgrep) is taken from the file.

       -x     (Exact) only lines matched in their entirety are printed (fgrep only).

       Care should be taken when using the characters $ * [ ^ | ? ' " ( ) and  in the expression as they are also meaningful to the Shell.  It is
       safest to enclose the entire expression argument in single quotes ' '.

       Fgrep searches for lines that contain one of the (newline-separated) strings.

       Egrep accepts extended regular expressions.  In the following description `character' excludes newline:

	      A  followed by a single character matches that character.

	      The character ^ ($) matches the beginning (end) of a line.

	      A .  matches any character.

	      A single character not otherwise endowed with special meaning matches that character.

	      A string enclosed in brackets [] matches any single character from the string.  Ranges of ASCII character codes may  be  abbreviated
	      as  in `a-z0-9'.	A ] may occur only as the first character of the string.  A literal - must be placed where it can't be mistaken as
	      a range indicator.

	      A regular expression followed by * (+, ?) matches a sequence of 0 or more (1 or more, 0 or 1) matches of the regular expression.

	      Two regular expressions concatenated match a match of the first followed by a match of the second.

	      Two regular expressions separated by | or newline match either a match for the first or a match for the second.

	      A regular expression enclosed in parentheses matches a match for the regular expression.

       The order of precedence of operators at the same parenthesis level is [] then *+? then concatenation then | and newline.

SEE ALSO

       ed(1), sed(1), sh(1)

DIAGNOSTICS

       Exit status is 0 if any matches are found, 1 if none, 2 for syntax errors or inaccessible files.

BUGS

       Ideally there should be only one grep, but we don't know a single algorithm that spans a wide enough range of space-time tradeoffs.

       Lines are limited to 256 characters; longer lines are truncated.

																	   GREP(1)