grep(1) 						      General Commands Manual							   grep(1)

NAME

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

SYNOPSIS

   Plain call with pattern
       pattern [file ...]

   Call with (multiple) -e pattern
       pattern] ...  [file ...]

   Call with -f file
       pattern_file] [file ...]

   Obsolescent:
       [expression] [file ...]

       [strings] [file ...]

DESCRIPTION

       The  command  searches  the input text files (standard input default) for lines matching a pattern.  Normally, each line found is copied to
       the standard output.  supports the Basic Regular Expression syntax (see regexp(5)).  The option supports Extended Regular Expression  (ERE)
       syntax  (see  regexp(5)).   The	option	searches for fixed strings using the fast Boyer-Moore string searching algorithm.  The and options
       treat newlines embedded in the pattern as alternation characters.  A null expression or string matches every line.

       The forms and are maintained for backward compatibility.  The use of the and options is recommended for portability.

   Options
	      Extended regular expressions.
				  Each pattern specified is a sequence of one or more EREs.  The EREs can be separated by  newline  characters	or
				  given  in  separate  expression options.  A pattern matches an input line if any ERE in the sequence matches the
				  contents of the input line without its trailing newline character.  The same functionality is obtained by using

	      Fixed strings.	  Each pattern specified is a sequence of one or more strings.	Strings can be separated by newline characters	or
				  given  in  separate expression options.  A pattern matches an input line if the line contains any of the strings
				  in the sequence.  The same functionality is obtained by using

	      Each line is preceded by the block number on which it was found.
				  This is useful in locating disk block numbers by context.  Block numbers are calculated by dividing by  512  the
				  number of bytes that have been read from the file and rounding down the result.

	      Only a count of matching lines is printed.

	      Same as a simple	  expression argument, but useful when the expression begins with a hyphen Multiple options can be used to specify
				  multiple patterns; an input line is selected if it matches any of the specified patterns.

	      The regular	  expression and or strings list is taken from the pattern_file.

	      Suppress printing of filenames when searching multiple files.

	      Ignore uppercase/lowercase distinctions during comparisons.

	      Only the names of files with matching lines are listed (once),
				  separated by newlines.  If standard input is searched, a path name of will be written, in the POSIX  locale.	In
				  other locales, may be replaced by something more appropriate in those locales.

	      Each line is preceded by its relative line number in the file starting at 1.
				  The line number is reset for each file searched.  This option is ignored if or is specified.

	      (Quiet)		  Do  not write anything to the standard output, regardless of matching lines.	Exit with zero status upon finding
				  the first matching line.  Overrides any options that would produce output.

	      Error messages produced for nonexistent or unreadable files are suppressed.

	      All lines but those matching are printed.

	      Select only those lines containing matches that
				  form whole words. The test is that the matching substring must either be at the beginning of the line,  or  pre-
				  ceded by a non-word constituent character.  Similarly, it must be either at the end of the line or followed by a
				  non-word constituent character. Word-constituent characters are letters, digits, and the underscore.

	      (eXact)		  Matches are recognized only when the entire input line matches the fixed string or regular expression.

       The file name is output in all the cases in which output is generated if there are more than one input file, unless the -h option is speci-
       fied.   Care  should  be taken when using the characters and in expression, because they are also meaningful to the shell.  It is safest to
       enclose the entire expression argument in single quotes

EXTERNAL INFLUENCES

   Environment Variables
       determines the locale to use for the locale categories when both and the corresponding environment variable (beginning with do not  specify
       a locale.  If is not specified or is set to the empty string, a default of (see lang(5)) is used.

       determines  the locale to use to override any values for locale categories specified by the settings of or any environment variables begin-
       ning with

       determines the collating sequence used in evaluating regular expressions.

       determines the interpretation of text as single byte and/or multi-byte characters, the classification of characters as  letters,  the  case
       information for the option, and the characters matched by character class expressions in regular expressions.

       determines the language in which messages are displayed.

       If  any	internationalization variable contains an invalid setting, the commands behave as if all internationalization variables are set to
       See environ(5).

   International Code Set Support
       Single-byte and multi-byte character code sets are supported.

RETURN VALUE

       Upon completion, returns one of the following values:

	      One or more matches found.
	      No match found.
	      Syntax error or inaccessible file (even if matches were found).

EXAMPLES

       In the POSIX shell (sh(1)) the following example searches two files, finding all lines containing occurrences of any of four strings:

       Note that the single quotes are necessary to tell when the strings have ended and the file names have begun.

       For the C shell (see csh(1)) the following command can be used:

       To search a file named containing the following entries:

       the command:

       prints:

       To search a file for lines that contain either a or use either of the following commands:

       Search all files in the current directory for the string

       Search all files in the current directory subtree for the string and ensure that no error occurs due to file name expansion exceeding  sys-
       tem argument list limits:

       The  previous  example  does  not print the name of files where string appears.	To force to print file names, add a second argument to the
       command portion of the command line:

       In this form, the first file name is that produced by and the second file name is the null file.

WARNINGS

       (XPG4 only.) If the option is specified, the exit status will be zero if an input line is selected, even if an error was detected.   Other-
       wise, default actions will be performed.

       If the option is specified with non-word constituent characters, then the output is unexpected.

SEE ALSO

       sed(1), sh(1), regcomp(3C), environ(5), lang(5), regexp(5).

STANDARDS CONFORMANCE

																	   grep(1)