Locate Linux Files by Their Name or Extension
Type find into the command line to track down a particular file by its name or extension. If you want to look for *.err files in the /home/username/ directory and all sub-directories, try this:
find /home/username/ -name “*.err”
Typical Linux Find Commands and Syntax
find command expressions look like this:
find command options starting/path expression
The options attribute controls the behavior and optimization method of the find process. The starting/path attribute defines the top-level directory where the find command in Linux begins the filtering process. The expression attribute controls the assessments that scour the directory tree to create output.
Let’s break down a Linux find command where we don’t just want Linux find file by name:
find -O3 -L /var/www/ -name “*.html”
It enables the top-level optimization (-O3) and permits find to follow symbolic links (-L). The find command in Linux searches through the whole directory hierarchy under /var/www/ for files that have .html on the end.
Basic Examples
1. find . -name thisfile.txt
If you need to know how to find a file in Linux called thisfile.txt, it will look for it in current and sub-directories.
2. find /home -name *.jpg
Look for all .jpg files in the /home and directories below it.
3. find . -type f -empty
Look for an empty file inside the current directory.
4. find /home -user randomperson-mtime 6 -iname “.db”
Look for all .db files (ignoring text case) that have been changed in the preceding 6 days by a user called randomperson.
Options and Optimization for Find Command for Linux
find is configured to ignore symbolic links (shortcut files) by default. If you’d like the find command to follow and show symbolic links, just add the -L option to the command, as we did in this example.
find can help Linux find file by name. The Linux find command enhances its approach to filtering so that performance is optimised. The user can find a file in Linux by selecting three stages of optimisation-O1, -O2, and -O3. -O1 is the standard setting and it causes find to filter according to filename before it runs any other tests.
-O2 filters by name and type of file before carrying on with more demanding filters to find a file in Linux. Level -O3 reorders all tests according to their relative expense and how likely they are to succeed.
- -O1 – (Default) filter based on file name first
- -O2 – File name first, then file-type
- -O3 – Allow find to automatically re-order the search based on efficient use of resources and likelihood of success
- -maxdepth X – Search this directory along with all sub-directories to a level of X
- -iname – Search while ignoring text case.
- -not – Only produce results that don’t match the test case
- -type f – Look for files
- -type d – Look for directories
Find Files by When They Were Modified
The Linux find command contains the ability to filter a directory hierarchy based on when the file was last modified:
find / -name “*jpg” -mtime 5
find /home/randomuser/ -name “*jpg” -mtime 4
The initial Linux find command pulls up a list of files in the whole system that end with the characters jpg and have been modified in the preceding 5 days. The next one filters randomuser’s home directory for files with names that end with the characters “conf” and have been modified in the preceding 4 days.
Use Grep to Find Files Based on Content
The find command in Linux is great but it can only filter the directory tree according to filename and meta data. To search files based on what they contain you’ll need a tool like grep. Take a look:
find . -type f -exec grep “forinstance” ‘{}’ \; -print
This goes through every object in the current directory tree (.) that’s a file (-type f) and then runs grep ” forinstance ” for every file that matches, then prints them on the screen (-print). The curly braces ({}) are a placeholder for those results matched by the Linux find command. The {} go inside single quotes (‘) so that grep isn’t given a misshapen file name. The -exec command is ended with a semicolon (;), which also needs an escape (\;) so that it doesn’t end up being interpreted by the shell.
Before -exec was implemented, xargs would have been used to create the same kind of output:
find . -type f -print | xargs grep “forinstance”
How to Locate and Process Files Using the Find Command in Linux
The -exec option runs commands against every object that matches the find expression. Let’s see how that looks:
find . -name “rc.conf” -exec chmod o+r ‘{}’ \;
This filters all objects in the current directory tree (.) for files named rc.conf and runs the chmod o+r command to alter file permissions of the results that find returns.
The root directory of the Linux is where the commands that -exec runs are executed. Use -execdir to execute the command you want in the directory where the match is sitting, because this might be more secure and improve performance under certain circumstances.
The -exec or -execdir options will continue to run on their own, but if you’d like to see prompts before they do anything, swap out -exec -ok or -execdir for -okdir.
Finding and Deleting using the Linux Command Line
*Be very careful about using this option.*
If you put -delete at the end of a match expression it will delete every file that matches, so you need to be absolutely sure that the results you are going to get will definitely be for the files that you want to delete. It goes without saying that you could wreak havoc on the system if you get this wrong!
In this example, find turns up every file in the directory tree, beginning with the present one, and deletes all files that end with the characters .bak:
find . -name “*.bak” -delete
