-E     Match using extended regular expressions. Treat each pattern specified as an ERE, as described  in
       the  Base  Definitions  volume of IEEE Std 1003.1-2001, Section 9.4, Extended Regular Expressions.
       If any entire ERE pattern matches some part of an input line excluding the terminating  <newline>,
       the line shall be matched.  A null ERE shall match every line.

-F     Match  using  fixed  strings.  Treat  each  pattern  specified  as  a  string instead of a regular
       expression. If an input line contains any of the patterns as a contiguous sequence of  bytes,  the
       line shall be matched. A null string shall match every line.

-c     Write only a count of selected lines to standard output.

-e  pattern_list

       Specify one or more patterns to be used during the search for input.  The application shall ensure
       that patterns in pattern_list are separated by a <newline>. A null pattern can be specified by two
       adjacent  <newline>s  in  pattern_list. Unless the -E or -F option is also specified, each pattern
       shall be treated as a BRE, as described in the Base Definitions  volume  of  IEEE Std 1003.1-2001,
       Section  9.3,  Basic Regular Expressions. Multiple -e and -f options shall be accepted by the grep
       utility. All of the specified patterns shall be  used  when  matching  lines,  but  the  order  of
       evaluation is unspecified.

-f  pattern_file

       Read  one  or  more  patterns  from  the  file  named  by  the pathname pattern_file.  Patterns in
       pattern_file shall be terminated by a <newline>. A null pattern can be specified by an empty  line
       in  pattern_file. Unless the -E or -F option is also specified, each pattern shall be treated as a
       BRE, as described in the Base Definitions  volume  of  IEEE Std 1003.1-2001,  Section  9.3,  Basic
       Regular Expressions.

-i     Perform  pattern  matching  in searches without regard to case; see the Base Definitions volume of
       IEEE Std 1003.1-2001, Section 9.2, Regular Expression General Requirements.

-l     (The letter ell.) Write only the names of files containing  selected  lines  to  standard  output.
       Pathnames  shall  be written once per file searched. If the standard input is searched, a pathname
       of "(standard input)" shall be written, in the POSIX locale. In other  locales,  "standard  input"
       may be replaced by something more appropriate in those locales.

-n     Precede  each  output  line by its relative line number in the file, each file starting at line 1.
       The line number counter shall be reset for each file processed.

-q     Quiet. Nothing shall be written to the standard output, regardless of matching  lines.  Exit  with
       zero status if an input line is selected.

-s     Suppress  the  error  messages ordinarily written for nonexistent or unreadable files. Other error
       messages shall not be suppressed.

-v     Select lines not matching any of the specified patterns.  If  the  -v  option  is  not  specified,
       selected lines shall be those that match any of the specified patterns.

-x     Consider  only input lines that use all characters in the line excluding the terminating <newline>
       to match an entire fixed string or regular expression to be matching lines.