Introduction
Within Linux, there are hundreds of ways to find a file. It all depends on what you are most comfortable using. Back in the day, located was the poison of choice, but after learning find, it was soon replaced. Find is a very powerful utility, especially when it comes to looking for specific files.
The Search
The basic syntax is as follows:
find /directory -name "\*" -print |xargs grep 'searchstring'
Here is an example looking for which file the /usr/local/apache-2.2 directory contains the word Directory:
find /usr/local/apache-2.2/ -type f -print |xargs grep "Directory" | head 6
Binary file /usr/local/apache-2.2/bin/httpd matches
/usr/local/apache-2.2/bin/apxs: error("Directory `$name' already exists. Remove first");
/usr/local/apache-2.2/include/http_config.h: NO_ARGS, /** Directory **/
/usr/local/apache-2.2/include/http_config.h: #define OR_LIMIT 1 /** <Directory> or <location> **/
...
Note: If you are looking for a file that requires root privileges (outside your allowed directories), you can use sudo before the words find and xargs. If you don't, you will get flooded with 'Permission Denied' and 'No such file or directory' error's:
sudo find /usr/local/apache-2.2/ -type f -print |sudo xargs grep "Directory"
Update - 4/12/2012
If you have a file with spaces in it, the above will fail. To remedy this situation use the following syntax:
find . -print0 | xargs -0 grep "what to grep for"
Since a filename with spaces will be seen as multi-arguments, grep will fail with file not found. Suffixing print with 0 sets the output to argument 0 for find, and adding the 0 option to xargs calls specifically argument 0.
