Finding Files by Content in bash

How do you find a file of some known content?

Let’s say that you had written an important letter and saved it as a text file, putting .txt on the end of the filename.
Beyond that, the only thing you remember about the content of the letter is that you had used the word “portend.”

If you are in the vicinity of that file, say within the current directory, you can start with a simple grep:

With the -i option, grep will ignore upper- and lowercase difference.

This command may not be sufficient to find what you’re looking for, but start simply.

Of course, if you think the file might be in one of your many subdirectories, you can try to reach all the files that are in subdirectories of the current directory with this command:

Let’s face it, though, that’s not a very thorough search.
If that doesn’t do it, let’s use a more complete solution: the find command.

Use the -exec option on find so that if the predicates are true up to that point, it will execute a command for each file it finds.

You can invoke grep or other utilities like this:

We use the -name ‘*.txt’ construct to help narrow down the search.

Any such test will help, since having to run a separate executable for each file that it finds is costly in time and CPU horsepower.

Maybe you have a rough idea of how old the file is (e.g., -mdate -5 or some such).

The ‘{}’ is where the filename is put when executing the command.

The \; indicates the end of the command, in case you want to continue with more predicates.
Both the braces and the semicolon need to be escaped, so we quote one and use the backslash for the other.

It doesn’t matter which way we escape them, only that we do escape them, so that bash doesn’t misinterpret them.
On some systems, the -H option will print the name of the file if grep finds something.

Normally, with only one filename on the command, grep won’t bother to name the file, it just prints out the matching line that it finds.

Since we’re searching through many files, we need to know which file was grepped.
If you’re running a version of grep that doesn’t have the -H option, then just put /dev/ null as one of the filenames on the grep command.

The grep command will then have more than one file to open, and will print out the filename if it finds the text.