How to grep a string from all the files under /

thomas2004ch · 09-15-2009, 05:09 AM

I am looking for files which contains a string for example "my text". But I don't know where the file locates. So I look for all the files do as follow (seems crazy):

Code:

grep -r "my text" *

But I can't get any result though there are indeed files which contain such string.

Is this command wrong?

lutusp · 09-15-2009, 05:36 AM

Quote:

Originally Posted by thomas2004ch

I am looking for files which contains a string for example "my text". But I don't know where the file locates. So I look for all the files do as follow (seems crazy):

Code:

grep -r "my text" *

But I can't get any result though there are indeed files which contain such string.

Is this command wrong?

Yes. Try this:

Code:

path="/path/of/interest"
search="my string"

find $path -type f | while read filepath
do
   if grep -iqP "\b$search\b" "$filepath"
   then
      echo "String \"$search\" found in file \"$filepath\"."
   fi
done

rizwanrafique · 09-15-2009, 05:57 AM

This should work all recent versions of bash.

Code:

grep -R "my text" *

thomas2004ch · 09-15-2009, 06:52 AM

Quote:

Originally Posted by lutusp

Yes. Try this:

Code:

path="/path/of/interest"
search="my string"

find $path -type f | while read filepath
do
   if grep -iqP "\b$search\b" "$filepath"
   then
      echo "String \"$search\" found in file \"$filepath\"."
   fi
done

I find your solution is a little bit too complicated.

pwc101 · 09-15-2009, 06:55 AM

Quote:

Originally Posted by lutusp

Yes. Try this:

Code:

path="/path/of/interest"
search="my string"

find $path -type f | while read filepath
do
   if grep -iqP "\b$search\b" "$filepath"
   then
      echo "String \"$search\" found in file \"$filepath\"."
   fi
done

This will be quite slow for a large number of hits as you're launching a new instance of grep for every file you find; you can just put the grep into the find command using the + instead of \; termination, then grep will be given a large number of files instead of only a single file:

Code:

find /path/of/interest -type f -exec grep "my string" "{}" +

Just a thought.

thomas2004ch · 09-15-2009, 08:03 AM

Quote:

Originally Posted by rizwanrafique

This should work all recent versions of bash.

Code:

grep -R "my text" *

I've tried and this is the same as "grep -r "my text" * what I used.

thomas2004ch · 09-15-2009, 08:32 AM

Quote:

Originally Posted by pwc101

This will be quite slow for a large number of hits as you're launching a new instance of grep for every file you find; you can just put the grep into the find command using the + instead of \; termination, then grep will be given a large number of files instead of only a single file:

Code:

find /path/of/interest -type f -exec grep "my string" "{}" +

Just a thought.

Yes, you are right. It will take very very long to find out the files. I am not sure if there is a best way.

The problem by your solution is, one has to know the path.

pwc101 · 09-15-2009, 08:54 AM

Quote:

Originally Posted by thomas2004ch

Yes, you are right. It will take very very long to find out the files. I am not sure if there is a best way.

The "best way" does not exist. For anything. All you can di is find the approach which suits the problem you are trying to overcome with minimal negative side effects.

Quote:

Originally Posted by thomas2004ch

The problem by your solution is, one has to know the path.

Not necessarily. You can supply a search path of /, or refine the other search criteria further, using mtime/atime/ctime, size etc.

GrapefruiTgirl · 09-15-2009, 09:01 AM

If the above methods were too complicated and/or didn't produce the results you want, you may not find this any better, but try:

Code:

for files in $(find / -name "*" -type f); do
 [ "$(grep -e "Volkerding" "$files")" ] && echo "$files"
done

..replace "Volkerding" with the string you seek.

Sasha

quanta · 09-15-2009, 09:12 AM

Quote:

Originally Posted by thomas2004ch

I am looking for files which contains a string for example "my text". But I don't know where the file locates. So I look for all the files do as follow (seems crazy):

Code:

grep -r "my text" *

But I can't get any result though there are indeed files which contain such string.

Is this command wrong?

Try using the following command:

Code:

grep -lir "your text" /

dwives · 09-15-2009, 10:46 AM

Obvious newbie question(or answer?)... Why couldn't you just use

ls / | grep -switch "string"

?

pwc101 · 09-15-2009, 10:51 AM

Quote:

Originally Posted by dwives

Obvious newbie question(or answer?)... Why couldn't you just use

ls / | grep -switch "string"

?

Because that would only pass a list of the directories immediately under / to grep which would then only output those that matched "string". Using find or a recursive option allows the full tree to be passed. For example, given the following directory structure:

Code:

/root
/root/subdir1
/root/subdir2
/root/subdir2/subsubdir1
/root/subdir3
/root/subdir3/subsubdir2

Your code would only pass the subdirs as arguments to the grep command. Using either find or -R passes the subdirs and the subsubdirs - the commands travel through the entire tree.

dwives · 09-15-2009, 11:06 AM

Quote:

Originally Posted by pwc101

Because that would only pass a list of the directories immediately under / to grep which would then only output those that matched "string". Using find or a recursive option allows the full tree to be passed. For example, given the following directory structure:

Code:

/root
/root/subdir1
/root/subdir2
/root/subdir2/subsubdir1
/root/subdir3
/root/subdir3/subsubdir2

Your code would only pass the subdirs as arguments to the grep command. Using either find or -R passes the subdirs and the subsubdirs - the commands travel through the entire tree.

So it would work with the -R arguement?

pwc101 · 09-15-2009, 11:08 AM

Quote:

Originally Posted by dwives

So it would work with the -R arguement?

This is what the manpage has to say on the matter:

Quote:

Originally Posted by man grep

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

However, my experience is this is not so fool-proof as using find to get a list of files, then passing that list to grep separately. See above for my suggestion.

GrapefruiTgirl · 09-15-2009, 11:08 AM

Quote:

Originally Posted by dwives

So it would work with the -R arguement?

Also, `ls` does not produce a full path of the file being examined, so while the -R option will cause recursion of `ls` itself, it will not produce helpful results, like a full path to the file wherein the string may have been found.

EDIT: And, as pwc101 hinted at above, ls can produce results that the next-in-pipe command has troubles with, producing weird errors.

Cheers

Sasha