how to find files containing a string using egrep

Question

I would like to find the files containing specific string under linux. I tried something like but could not succeed:

find . -name *.txt | egrep mystring

Answer 1

try:

find . -name '*.txt' | xargs egrep mystring

There are two problems with your version:

Firstly, *.txt will first be expanded by the shell, giving you a listing of files in the current directory which end in .txt, so for instance, if you have the following:

[dsm@localhost:~]$ ls *.txt
test.txt
[dsm@localhost:~]$

your find command will turn into find . -name test.txt. Just try the following to illustrate:

[dsm@localhost:~]$ echo find . -name *.txt
find . -name test.txt
[dsm@localhost:~]$

Secondly, egrep does not take filenames from STDIN. To convert them to arguments you need to use xargs

Answer 2

Here you are sending the file names (output of the find command) as input to egrep; you actually want to run egrep on the contents of the files.

Here are a couple of alternatives:

find . -name "*.txt" -exec egrep mystring {} \;

or even better

find . -name "*.txt" -print0 | xargs -0 egrep mystring

Check the find command help to check what the single arguments do.
The first approach will spawn a new process for every file, while the second will pass more than one file as argument to egrep; the -print0 and -0 flags are needed to deal with potentially nasty file names (allowing to separate file names correctly even if a file name contains a space, for example).

Answer 3

find . -name *.txt | egrep mystring

That will not work as egrep will be searching for mystring within the output generated by find . -name *.txt which are just the path to *.txt files.

Instead, you can use xargs:

find . -name *.txt | xargs egrep mystring

Answer 4

You could use

find . -iname *.txt -exec egrep mystring \{\} \;

Answer 5

Here's an example that will return the file paths of a all *.log files that have a line that begins with ERROR:

find . -name "*.log" -exec egrep -l '^ERROR' {} \;

Answer 6

there's a recursive option from egrep you can use

egrep -R "pattern" *.log

Answer 7

If you only want the filenames:

find . -type f -name '*.txt' -exec egrep -l pattern {} \;

If you want filenames and matches:

find . -type f -name '*.txt' -exec egrep pattern {} /dev/null \;