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About grep : How-can-I-grep-recursively-but-only-in-files-with-certain-extensions

Question Detail

I’m working on a script to grep certain directories:

{ grep -r -i CP_Image ~/path1/;
grep -r -i CP_Image ~/path2/;
grep -r -i CP_Image ~/path3/;
grep -r -i CP_Image ~/path4/;
grep -r -i CP_Image ~/path5/; }
| mailx -s GREP [email protected]

How can I limit results only to extensions .h and .cpp?

Question Answer

Just use the --include parameter, like this:

grep -inr --include \*.h --include \*.cpp CP_Image ~/path[12345] | mailx -s GREP [email protected]

That should do what you want.

To take the explanation from HoldOffHunger’s answer below:

  • grep: command

  • -r: recursively

  • -i: ignore-case

  • -n: each output line is preceded by its relative line number in the file

  • --include \*.cpp: all *.cpp: C++ files (escape with \ just in case you have a directory with asterisks in the filenames)

  • ./: Start at current directory.

Some of these answers seemed too syntax-heavy, or they produced issues on my Debian Server. This worked perfectly for me:

grep -r --include=\*.txt 'searchterm' ./

…or case-insensitive version…

grep -r -i --include=\*.txt 'searchterm' ./
  • grep: command

  • -r: recursively

  • -i: ignore-case

  • --include: all *.txt: text files (escape with \ just in case you have a directory with asterisks in the filenames)

  • 'searchterm': What to search

  • ./: Start at current directory.

Source: PHP Revolution: How to Grep files in Linux, but only certain file extensions?

grep -rnw "some thing to grep" --include=*.{module,inc,php,js,css,html,htm} ./


find . -name '*.h' -o -name '*.cpp' -exec grep "CP_Image" {} \; -print

There isn’t any -r option on HP and Sun servers, but this way worked for me on my HP server:

find . -name "*.c" | xargs grep -i "my great text"

-i is for case insensitive search of string.

This answer is good:

grep -r -i --include \*.h --include \*.cpp CP_Image ~/path[12345] | mailx -s GREP [email protected]

But it can be updated to:

grep -r -i --include \*.{h,cpp} CP_Image ~/path[12345] | mailx -s GREP [email protected]

Which can be simpler.

Since this is a matter of finding files, let’s use find!

Using GNU find you can use the -regex option to find those files in the tree of directories whose extension is either .h or .cpp:

find -type f -regex ".*\.\(h\|cpp\)"
#            ^^^^^^^^^^^^^^^^^^^^^^^

Then, it is just a matter of executing grep on each of its results:

find -type f -regex ".*\.\(h\|cpp\)" -exec grep "your pattern" {} +

If you don’t have this distribution of find you have to use an approach like Amir Afghani’s, using -o to concatenate options (the name is either ending with .h or with .cpp):

find -type f \( -name '*.h' -o -name '*.cpp' \) -exec grep "your pattern" {} +
#            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

And if you really want to use grep, follow the syntax indicated to --include:

grep "your pattern" -r --include=*.{cpp,h}
#                      ^^^^^^^^^^^^^^^^^^^

The easiest way is:

find . -type  f -name '*.extension' 2>/dev/null | xargs grep -i string

Add 2>/dev/null to kill the error output.

To include more file extensions and grep for password throughout the system:

find / -type  f \( -name '*.conf' -o -name "*.log" -o -name "*.bak" \) 2>/dev/null |
xargs grep -i password

ag (the silver searcher) has pretty simple syntax for this

       -G --file-search-regex PATTERN
          Only search files whose names match PATTERN.


ag -G *.h -G *.cpp CP_Image <path>

You should write “-exec grep ” for each “-o -name “:

find . -name '*.h' -exec grep -Hn "CP_Image" {} \; -o -name '*.cpp' -exec grep -Hn "CP_Image" {} \;

Or group them by ( )

find . \( -name '*.h' -o -name '*.cpp' \) -exec grep -Hn "CP_Image" {} \;

Option ‘-Hn’ shows the file name and line.

Here is a method I normally use to find .c and .h files:

tree -if | grep \\.[ch]\\b | xargs -n 1 grep -H "#include"

Or if you need the line number as well:

tree -if | grep \\.[ch]\\b | xargs -n 1 grep -nH "#include"

If you want to filter out extensions from the output of another command e.g. “git”:

files=$(git diff --name-only --diff-filter=d origin/master... | grep -E '\.cpp$|\.h$')

for file in $files; do
    echo "$file"

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