NAME
      grep - print lines matching a pattern

SYNOPSIS
      grep [OPTION...] PATTERN [FILE...]
      grep [OPTION...] [-e PATTERN | -f FILE] [FILE...]

DESCRIPTION
      grep searches the named input FILEs, or standard input if no files are named, for lines containing a match to the given PATTERN. By default, grep prints the matching lines.

OPTIONS
      -c
      Suppress normal output; instead print a count of matching lines for each input file. With the -v option, count non-matching lines.

      -e PATTERN
      Use PATTERN as the pattern. This can be used to specify multiple search patterns.

      -f FILE
      Obtain patterns from FILE, one per line. This can be used to protect a pattern beginning with a hyphen (-).

      -H
      Print the file name for each match. This is the default when there is more than one file to search.

      -h
      Suppress the prefixing of file names on output. This is the default when there is only one file to search.

      -i
      Ignore case distinctions in the input files.

      -L
      Suppress normal output; instead print the name of each input file from which no output would normally have been printed.

      -l
      Suppress normal output; instead print the name of each input file from which output would normally have been printed.

      -n
      Prefix each line of output with the 1-based line number within its input file.

      -r
      Read all files under each directory recursively.

      -v
      Invert the sense of matching, to select non-matching lines.

EXAMPLES
      To search for user tariq under /etc/passwd using \grep command:

grep tariq /etc/passwd

      To force grep to ignore word case i.e mach tariq, Tariq, TARIQ and all other combinations use the -i option:

grep -i "TARIQ" /etc/passwd

      To search recursively use the -r option

grep -r "192.168.1.5" /etc/

      To count lines when words are matched use the -c option with grep
      Sample File:
      1>\cat pattern-test.txt
      Mary had a little lamb
      Mary fried a lot of spam
      Jack ate a Spam sandwich
      Jill had a lamb spamwich

grep -c Mary pattern-test.txt 

      Grep invert match, use the -v option

grep -v Mary pattern-test.txt

      To print the filename for each match together with the matched line, use the -H option:

grep -H Mary *.txt

      To suppress the filenames on output, use the -h option

grep -h Mary *.txt

      To print the name of files in a directory, which does not match the pattern, use the -L option

grep -L Mary *.txt

      To list the name of matching files with the specified pattern use the -l option

grep -l Mary *.txt

      To combine grep with other availabe commands in the fluidshell use pipes

cat pattern-test.txt | grep -h Mary *.txt

NOTES
      If both -H and -h are specified, headers are not displayed.
      If both -L and -l are specified, -L takes precedence.
      If both -c and -r are specified, the output of count on directories is suppressed.

      If either -L or -l is specified, the scanning will stop on the first match.
      The following commands might generate a 'cat: file: Pipe closed' warning if a match is found:

cat file | grep -l pattern
cat file | grep -L pattern