search a file for a pattern

-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.

Before a command is executed, its input and output may be redirected using a special notation interpreted
by  the  shell.   Redirection  may  also  be used to open and close files for the current shell execution
environment.  The following redirection operators may precede or appear anywhere within a simple  command
or may follow a command.  Redirections are processed in the order they appear, from left to right.

Redirecting Output
    Redirection of output causes the file whose name results from the expansion of  word  to  be  opened  for
    writing  on  file descriptor n, or the standard output (file descriptor 1) if n is not specified.  If the
    file does not exist it is created; if it does exist it is truncated to zero size.

    The general format for redirecting output is:

           [n]>word

    If the redirection operator is >, and the noclobber option to the  set  builtin  has  been  enabled,  the
    redirection  will  fail if the file whose name results from the expansion of word exists and is a regular
    file.  If the redirection operator is >|, or the redirection operator is > and the  noclobber  option  to
    the  set  builtin  command  is  not  enabled, the redirection is attempted even if the file named by word
    exists.