Otherwise, the standard input shall not be '-' and the implementation treats the '-' as meaning standard input. The standard input shall be used if no file operands are specified, and shall be used if a file operand is If no file operands are specified, the standard input shall be file A pathname of a file to be searched for the patterns. This operand shall be treated as if it were specified as The following operands shall be supported: pattern_list Specify one or more patterns to be used during the search for input. x Consider only input lines that use all characters in the line excluding the terminating to match an entireįixed string or regular expression to be matching lines. Those that match any of the specified patterns. If the -v option is not specified, selected lines shall be v Select lines not matching any of the specified patterns. s Suppress the error messages ordinarily written for nonexistent or unreadable files. Exit with zero status if an input line is Nothing shall be written to the standard output, regardless of matching lines. The line number counter shallīe reset for each file processed. n Precede each output line by its relative line number in the file, each file starting at line 1. In other locales, 'standard input' may be replaced by something more appropriate in those locales. If the standard input is searched, a pathname of '(standard input)' shall be written, in the POSIX l (The letter ell.) Write only the names of files containing selected lines to standard output. i Perform pattern matching in searches without regard to case see XBD RegularĮxpression General Requirements. F option is also specified, each pattern shall be treated as a BRE, as described in XBD Basic Regular Expressions. A null pattern can be specified by an empty line in pattern_file. Read one or more patterns from the file named by the pathname pattern_file. All of the specified patterns shall be used when matching lines,īut the order of evaluation is unspecified. f options shall be accepted by the grep utility. Unless the -E or -F option is also specified, each pattern shall be treated as a BRE, asĭescribed in XBD Basic Regular Expressions. A null pattern can be specified by two adjacent characters The application shall ensure that patterns in Specify one or more patterns to be used during the search for input. c Write only a count of selected lines to standard output. If an input line containsĪny of the patterns as a contiguous sequence of bytes, the line shall be matched. Treat each pattern specified as a string instead of a regular expression. Input line excluding the terminating, the line shall be matched. If any entire ERE pattern matches some part of an Treat each pattern specified as an ERE, as described in XBD Extended Regular Expressions.

The following options shall be supported: -E Match using extended regular expressions.

The grep utility shall conform to XBD Utility Syntax Guidelines Similarly, since patterns are matchedĪgainst individual lines (excluding the terminating characters) of the input, there is no way for a pattern to e and -f options below), regular expressions cannot contain a. Since a separates or terminates patterns (see the Regular expression matching shall be based on text lines. By default, each selected input line shall be written to the Terminating a null BRE shall match every line. Byĭefault, an input line shall be selected if any pattern, treated as an entire basic regular expression (BRE) as described in XBD Basic Regular Expressions, matches any part of the line excluding the The pattern_list's value shall consist of one or more patterns separated by Ĭharacters the pattern_file's contents shall consist of one or more patterns terminated by a character. The patterns are specified by the -e option, -f option, or the The grep utility shall search the input files, selecting lines matching one or more patterns the types of patterns areĬontrolled by the options specified. NAME grep - search a file for a pattern SYNOPSIS The Open Group Base Specifications Isedition

Grep regular expression