Re: grep -R "include" *.c --- not working

[Stephane Chazelas]

2004-10-4, 10:17(-06), Bob Proulx:
> Stepan Kasal wrote:
>> since you already use two GNU-specific features (-r and -0 in xargs), you
>> could as well adopt another one:
>> 
>>     find . -name '*.c' -print0 | xargs -r0 grep -H include
>> or
>>     find . -name '*.c' -print0 | xargs -r0 grep --with-filename include
>
> Yes, I think your way here is best.  Since I am using the short -r
> option the short -H follows naturally.  You have converted me.
>
> I am always wanting to say the following.  This will work way back on
> virtually any system.  This is old classic way of doing it.
>
>   find . -name '*.c' -print | xargs grep 'some_pattern' /dev/null
>
> That works fine for the unix user who would never create files with
> spaces or newlines in them.
[...]

Not only spaces, also single and double quotes and backslashes.
find output is simply not suited for xargs input.

The POSIX version is:

find . -name '*.c' -exec grep 'some_pattern' {} +

Unfortunately, GNU find is not POSIX conformant on that one
(also note that GNU find won't report a file named ".c" or
".foo.c" although they match the pattern).

So, to be POSIX conformant and compatible with GNU find (and
some other old find implementations), one has to do:

find .//. \( -name '*.c' -o -name '.*.c' -o -name .c \) -print |
  sed 's/./\\&/g' | awk '
    {
      if (NR > 1) {
        printf "%s", line
        if ($0 !~ /\\\/\\\//) printf "\\"
        print ""
      }
      line = $0
    }
    END { print line }' | xargs grep /dev/null

Also not AT&T tw (http://www.research.att.com/~gsf/tw/tw.html)
(untested).

-- 
Stephane

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