how do i recursively grep (search text files) in unix?

What Unix/Linux flavour are you on?

thank you.

I tried -R but didn't work

when I tried the find command, hundreds of lines flew by.

I tried the -C2 command, but it  did nothing. I guess that's not the command and it was waiting for more input.

I am on redhat enterprise 2, and suse 10.

how do i know if my unix supports -R for grep other than finding it does not work.  I looked in info, and it mentioned it in the documenation, but maybe documentation is not specific to your unix.

could you show us the man page for your grep?

Define "didn't work".  

Did it give you more/less results than you expected?
Did it give an error?  If so, please post the *exact* error.

Please post a sample of the hundreds of lines that flew by when you ran the find command.

find . -type f -exec grep -C 2 {} \; -print | more

# where the -C 2 option only works if you have a GNU grep

cd to the parent (top level) directory you want to search from.

Try this little loop on the command line:  After the first line, you'll get > prompts to complete it

find . -type f -exec grep -l example {} \; | while read file
do
   echo "-- found in $file ---"
   echo "grep -2 example $file"
   echo "\n"
done

If needed you can pipe it to something like less, more a file etc.:
done | less
or
done | more
or
done >> myfile

man grep produces a file that's 300 lines long. do you want all the lines?


NAME
       grep, egrep, fgrep - print lines matching a pattern

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

DESCRIPTION
       Grep  searches  the named input FILEs (or standard input if no files are named, or the file name - is given) for
       lines containing a match to the given PATTERN.  By default, grep prints the matching lines.

       In addition, two variant programs egrep and fgrep are available.  Egrep is the same as grep -E.   Fgrep  is  the
       same as grep -F.

OPTIONS
       -A NUM, --after-context=NUM
              Print NUM lines of trailing context after matching lines.  Places a line containing -- between contiguous
              groups of matches.

       -a, --text
              Process a binary file as if it were text; this is equivalent to the --binary-files=text option.

i made a file called text.txt
put the word octopus in it

$find . -type f -exec grep -C 2 octopus \; -print | more
$

I get the shell prompt back again with nothing

man grep:


       -R, -r, --recursive
              Read all files under each directory, recursively; this is equivalent to the -d recurse option.

this is bizarre

if i
grep octopus *.*  
in my home directory which contains test.txt which says "octopus"
i get
test.txt:octopus
which is correct

however, if i go to a subdirectory which has the word octopus in that directory (in a text file) and in a subdirectory
and do
grep octopus *.*
then i only get the answer
octopus

and nothing about where it appears

if I do grep -r octopus *.*
same answer
octopus

okay. i see. if there is only one file in the directory, it doesn't give the file name.

grep -nr octopus *.*
give me the file name and line numbers
but is not looking in the subdirectory

okay
grep -nr octopus *
works

grep will only display a filename if there are two or more files being searched.

In your home directory, you will have more than one file, whereas in the subdirectory, you'll have a single file.

If you want to ensure you always have the filename reported, use the -H flag, eg:

grep -H octopus *

or on systems that don't have GNU grep, you can acheive the same by doing

grep octopus * /dev/null

Specifying a dummy file (/dev/null in this instance) forces grep to report the filename as it is effectively searching >1 files.