Using the find Command in Linux and UNIX

The find command allows users to do a comprehensive search spanning the directory tree. find also allows the setting of more specific options to filter the search results and when you’ve found what you’re looking for find even has the option to do some work on those files.

Finding Files by Age

What if a user wants to determine if there are any really old files on their server? There are dozens of options for the find command but the first thing find requires is the path in which to look.

In this example we will change our working directory to the / (root) directory and run the find command on the working directory by giving . as the path argument. The following command sequence looks for any files that are more than 20 years, 7300 days, old.

Finding files older than 20 years

# cd /
# find ./ -mtime +7300
# cd /tmp
# ls -ld orbit-root
drwx------ 2 root root 8192 Dec 31 1969 orbit-root

By default find prints the name and path to any files which match the criteria listed. In this case it has found a file in ./tmp/orbit-root which has not been modified in more than 7300 days.

You’ve probably noticed that the date on this file is a bit suspect. While the details are unimportant it is worth understanding that anything on a Linux system with a date of December 31, 1969 or January 1, 1970 has probably lost its date and time attributes somehow. It may have also been created at some time when the system’s clock was horribly wrong.

If we wanted to search the root directory without changing our working directory we could have specified the directory in the find command like this:

# find / -mtime +7300

The command found the same file in this case but has now described it starting with / instead of ./ because that is what was used in the find command.

The following command sequence will look for some newer files. The process starts in the user’s home directory and looks for files less than three days old.

Finding Any Files Modified in the Past 3 Days

$ cd ~
$ find . -mtime -3.

Now we start to really see the power of the find command. It has identified files not only in the working directory but in a subdirectory as well! Let’s verify the findings with some ls commands:

$ ls –alt
total 56
drwxrwxr-x 2 tclark authors 4096 Feb 3 17:45 examples
-rw------- 1 tclark tclark 8793 Feb 3 14:04 .bash_history
drwx------ 4 tclark tclark 4096 Feb 3 11:17 .
-rw------- 1 tclark tclark 1066 Feb 3 11:17 .viminfo
-rw-rw-r-- 1 tclark tclark 0 Feb 3 09:00 example1.fil
-rw-r--r-- 1 tclark authors 0 Jan 27 00:22 umask_example.fil
drwxr-xr-x 8 root root 4096 Jan 25 22:16 ..
-rw-rw-r-- 1 tclark tclark 0 Jan 13 21:13
-rw-r--r-- 1 tclark tclark 120 Aug 24 06:44 .gtkrc
-rw-r--r-- 1 tclark tclark 24 Aug 18 11:23 .bash_logout
-rw-r--r-- 1 tclark tclark 191 Aug 18 11:23 .bash_profile
-rw-r--r-- 1 tclark tclark 124 Aug 18 11:23 .bashrc
-rw-r--r-- 1 tclark tclark 237 May 22 2003 .emacs
-rw-r--r-- 1 tclark tclark 220 Nov 27 2002 .zshrc
drwxr-xr-x 3 tclark tclark 4096 Aug 12 2002 .kde
$ cd examples
$ ls -alt
total 20
drwxrwxr-x 2 tclark authors 4096 Feb 3 17:45 .
-rw-rw-r-- 1 tclark tclark 0 Feb 3 17:45 other.txt
-rw-rw-r-- 1 tclark authors 360 Feb 3 17:44 preamble.txt
drwx------ 4 tclark tclark 4096 Feb 3 11:17 ..
-rw-r--r-- 1 tclark authors 2229 Jan 13 21:35 declaration.txt
-rw-rw-r-- 1 tclark presidents 1310 Jan 13 17:48 gettysburg.txt

So we see that find has turned up what we were looking for. Now we will refine our search even further.

Finding .txt Files Modified in the Past 3 Days

Sometimes we are only concerned specific files in the directory. For example, say you wrote a text file sometime in the past couple days and now you can’t remember what you called it or where you put it. Here’s one way you could find that text file without having to go through your entire system:

$ find . -name '*.txt' -mtime -3

Now you’ve got even fewer files than in the last search and you could easily identify the one you’re looking for.

Find files by size

If a user is running short of disk space, they may want to find some large files and compress them to recover space. The following will search from the current directory and find all files larger than 10,000KB. The output has been abbreviated.

Finding Files Larger than 10,000k

# find . -size +10000k

Similarly a – could be used in this example to find all files smaller than 10,000KB. Of course there would be quite a few of those on a Linux system.

The find command is quite flexible and accepts numerous options. We have only covered a couple of the options here but if you want to check out more of them take a look at find’s man page.

Most of find’s options can be combined to find files which meet several criteria. To do this we can just continue to list criteria like we did when finding .txt files which had been modified in the past three days.

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2 thoughts on “Using the find Command in Linux and UNIX”

  1. Hi All! I also can never remember all the common options to the find command that I use. In case it help you can view my simple writeup at:

    My writeup has one major difference than this blog post in that it describes how to use the execute option to pass the find results to another program (such as grep). Hopefully it helps someone!

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