Info Catalog grep: Exit Status grep: Invoking

grep: grep Programs

 
 2.4 ‘grep’ Programs
 ===================
 
 ‘grep’ searches the named input files for lines containing a match to
 the given patterns.  By default, ‘grep’ prints the matching lines.  A
 file named ‘-’ stands for standard input.  If no input is specified,
 ‘grep’ searches the working directory ‘.’ if given a command-line option
 specifying recursion; otherwise, ‘grep’ searches standard input.  There
 are four major variants of ‘grep’, controlled by the following options.
 
 ‘-G’
 ‘--basic-regexp’
      Interpret patterns as basic regular expressions (BREs).  This is
      the default.
 
 ‘-E’
 ‘--extended-regexp’
      Interpret patterns as extended regular expressions (EREs).  (‘-E’
      is specified by POSIX.)
 
 ‘-F’
 ‘--fixed-strings’
      Interpret patterns as fixed strings, not regular expressions.
      (‘-F’ is specified by POSIX.)
 
 ‘-P’
 ‘--perl-regexp’
      Interpret patterns as Perl-compatible regular expressions (PCREs).
      PCRE support is here to stay, but consider this option experimental
      when combined with the ‘-z’ (‘--null-data’) option, and note that
      ‘grep -P’ may warn of unimplemented features.  ⇒Other
      Options.
 
    In addition, two variant programs ‘egrep’ and ‘fgrep’ are available.
 ‘egrep’ is the same as ‘grep -E’.  ‘fgrep’ is the same as ‘grep -F’.
 Direct invocation as either ‘egrep’ or ‘fgrep’ is deprecated, but is
 provided to allow historical applications that rely on them to run
 unmodified.
 

Info Catalog grep: Exit Status grep: Invoking