Tuesday, November 20, 2007

Linux: Find files on your computer with find

A standard Linux system has an incredible amount of files installed. Looking for a file location can be a painful task to do though a file browser.

Fortunately, there is a nifty command line available by default on any Linux distribution: find.

find can virtually find anything on your computer and comes with a lot of options. This tutorial will introduce a basic use of it and show how you can search your filesystem for file names matching a name pattern.

On Debian based distros, find is part of the package findutils. find allow one to search for files on a filesystem based on different condition, creation date, modified date, file size, file type, permissions, name ....

In this tutorial, I will be focused on finding files/directories based on their name, in order to explain in more depth the syntax of find, I will also show how you can narrow down your search by adding condition on size and file modification time.

This will suit most searches, if you need more details, I would recommend looking at the find's manpage.

1. Find basis

The default syntax of find is as such:

find [path] [expression]

where path is the path used as root for searching pattern and expression the expression we want the file to match.

2. Finding a file based on filename

Let say for instance you want to find all .avi files in users home directories. Search files can be found with the following command:

# find /home -name '*.avi'

If you want to search for *.mpg and *.avi files, you will use the following:

find /home -name '*.mpg' -o -name '*.avi'

Case insensitive searches can be achieved by using the -iname switch:

find /home -iname '*.mpg' -o -iname '*.avi'

3. Adding some more criterias

Those kind of searches might returns far too many results, making it hard to find waht you were looking for in the first place.

Fortunately, you can narrow down the search by adding criteria such as the file size and the file modification date.

Let'search for .avi files bigger than 700M. This can be done with:

find /home/ -name '*.avi' -a -size +700M

Now, let's find the same subset of files that were modified less than 15 days ago:

find /home/ -name '*.avi' -a -size +700M -mtime -15

4. Adding some actions

Grand, we can now find files based on a subset of criteria. What would be even better is to apply some actions on those files. Action can be done with the use of -exec switch.
We can now find .avi file that are newer that 15 days, in this example, we are going to move those file to another location: /my/new/movies . I consider that this directory already exist on your system.
Moving .avi files bigger than 700M and younger than 15 days to /my/new/movies can be done with:

find /home/ -name '*.avi' -a -size +700M -mtime -15 -exec mv '{}' /my/new/movies/ \;

Mind the use of '{}' and \; (there is a space before \;).
'{}' matches the file that was found, while \; terminate the exec statement.

5. Conclusion

find is a powerful tool with an extensive set of statement. This article only covered a small subset of available features. For more information on the find command I recommend checking out its man page.



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