how to Find Linux Files by Name or Extension via command line

Use find from the command line to locate a specific file by name or extension. The following example searches for *.log files in the /home/username/ directory and all sub-directories:

find /home/username/ -name "*.log"

Common Linux Find Commands and Syntax

find expressions take the following form:

find options starting/path expression

The options attribute will control the behavior and optimization method of the find process.
The starting/path attribute will define the top level directory where find begins filtering.
The expression attribute controls the tests that search the directory hierarchy to produce output.

Consider the following example command:

find -O3 -L /var/www/ -name "*.html"

This command enables the maximum optimization level (-O3) and allows find to follow symbolic links (-L). find searches the entire directory tree beneath /var/www/ for files that end with .html.

Basic examples

Command	Description
find . -name testfile.txt	Find a file called testfile.txt in current and sub-directories.
find /home -name *.jpg	Find all `.jpg` files in the `/home` and sub-directories.
find . -type f -empty	Find an empty file within the current directory.
find /home -user exampleuser -mtime -7 -iname “.db”	Find all `.db` files (ignoring text case) modified in the last 7 days by a user named exampleuser

Options and Optimization for Find

The default configuration for find will ignore symbolic links (shortcut files). If you want find to follow and return symbolic links, you can add the -L option to the command, as shown in the example above.

find optimizes its filtering strategy to increase performance. Three user-selectable optimization levels are specified as -O1, -O2, and -O3. The -O1 optimization is the default and forces find to filter based on filename before running all other tests.

Optimization at the -O2 level prioritizes file name filters, as in -O1, and then runs all file-type filtering before proceeding with other more resource-intensive conditions. Level -O3 optimization allows find to perform the most severe optimization and reorders all tests based on their relative expense and the likelihood of their success.

Command	Description
`-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 current directory as well as all sub-directories X levels deep.
`-iname`	Search without regard for text case.
`-not`	Return only results that do not match the test case.
`-type f`	Search for files.
`-type d`	Search for directorie

Find Files by Modification Time

The find command contains the ability to filter a directory hierarchy based on when the file was last modified:

find / -name "*conf" -mtime -7
find /home/exampleuser/ -name "*conf" -mtime -3

The first command returns a list of all files in the entire file system that end with the characters conf and have been modified in the last 7 days. The second command filters exampleuser user’s home directory for files with names that end with the characters conf and have been modified in the previous 3 days.

Use Grep to Find Files Based on Content

The find command is only able to filter the directory hierarchy based on a file’s name and meta data. If you need to search based on the content of the file, use a tool like grep. Consider the following example:

find . -type f -exec grep "example" '{}' ; -print

This searches every object in the current directory hierarchy (.) that is a file (-type f) and then runs the command grep "example" for every file that satisfies the conditions. The files that match are printed on the screen (-print). The curly braces ({}) are a placeholder for the find match results. The {} are enclosed in single quotes (') to avoid handing grep a malformed file name. The -exec command is terminated with a semicolon (;), which should be escaped (;) to avoid interpretation by the shell.

Before the implementation of the -exec option, this kind of command might have used the xargs command to generate a similar output:

find . -type f -print | xargs grep "example"

How to Find and Process Files Using the Find Command

The -exec option runs commands against every object that matches the find expression. Consider the following example:

find . -name "rc.conf" -exec chmod o+r '{}' ;

This filters every object in the current hierarchy (.) for files named rc.conf and runs the chmod o+r command to modify file permissions of the find results.

The commands run with the -exec are executed in the root directory of the find process. Use -execdir to execute the specified command in the directory where the match resides. This may alleviate security concerns and produce more desirable performance for some operations.

The -exec or -execdir options run without further prompts. If you prefer to be prompted before action is taken, replace -exec with -ok or -execdir with -okdir.

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