The find command is one of the most powerful tools in the Linux system administrators arsenal. It searches for files and directories in a directory hierarchy based on a user given expression and can perform user-specified action on each matched file.

You can use the find command to search for files and directories based on their permissions, type, date, ownership, size, and more. It can also be used in combination with other tools such as grep or sed.

Linux find Command Syntax

The general syntax for the find command is as follows:

find [options] [path...] [expression]
  • The options attribute controls the treatment of the symbolic links, debugging options, and optimization method.
  • The path... attribute defines the starting directory or directories where find will search the files.
  • The expression attribute is made up of options, search patterns, and actions separated by operators.

To search for files in a directory, the user invoking the find command needs to have read permissions on that directory.

Let’s take a look at the following example:

find -L /var/www -name "*.js"
  • The option -L (options) tells the find command to follow symbolic links.
  • The /var/www (path…) specifies the directory that will be searched.
  • The (expression) -name "*.js tells find to search files ending with .js (JavaScript files).

Find Files by Name

Finding files by name is probably the most common use of the find command. To find a file by its name use, the -name option followed the name of the file you are searching for.

For example, to search for a file named document.pdf in the /home/linuxize directory you would use the following command:

find /home/linuxize -type f -name document.pdf

To run a case-insensitive search, change the -name option with -iname:

find /home/linuxize -type f -iname document.pdf

The command above will match “Document.pdf”, “DOCUMENT.pdf” ..etc.

Find Files by Extension

Searching for files by extension is the same as searching for files by name. For example, to find all files ending with .log.gz inside the /var/log/nginx directory you can use:

find /var/log/nginx -type f -name '*.log.gz'

It is important to mention that when you use the wildcard character, you must either quote the pattern or escape the asterisk * symbol with backslash so that it doesn’t get interpreted by the shell.

To find all files that don’t match the regex *.log.gz you can use the -not option. For example, to find all files that don’t end in *.log.gz you would use:

find /var/log/nginx -type f -not -name '*.log.gz'

Find Files by Type

Sometimes you might need to search for specific file types such as normal files, directories or symlinks. In Linux, everything is a file.

To search for files based on their type, use the -type option and one the following descriptors to specify the file type:

  • f: a regular file
  • d: directory
  • l: symbolic link
  • c: character devices
  • b: block devices
  • p: named pipe (FIFO)
  • s: socket

For instance, to find all directories in the current working directory, you would use:

find . -type d

The common example would be to recursively change the website file permissions to 644 and directory permissions to 755 using the chmod command:

find /var/www/my_website -type d -exec chmod 0755 {} ;find /var/www/my_website -type f -exec chmod 0644 {} ;

Find Files by Size

To find files based on the file size, pass the -size parameter along with the size criteria. You can use the following suffixes to specify the file size:

  • b: 512-byte blocks (default)
  • c: bytes
  • w: two-byte words
  • k: Kilobytes
  • M: Megabytes
  • G: Gigabytes

The following command will find all files of exactly 1024 bytes inside the /tmp directory:

find /tmp -type f -size 1024c

The find command also allows you to search for files that are greater or less than a specified size.

In the following example, we are searching for all files less than 1MB inside the current working directory. Notice the minus - symbol before the size value:

find . -type f -size -1M

If you want to search for files with size greater than 1MB, then you need to use the plus symbol:

find . -type f -size  1M

You can even search for files within a size range. The following command will find all files between 1 and 2MB:

find . -type f -size  1M -size 21M

Find Files by Modification Date

The find command can also search for files based on their last modification, access, or change time.

Same as when searching by size, use the plus and minus symbols for “greater than” or “less than”.

Let’s say that a few days ago, you modified one of the dovecot configuration files, but you forgot which one. You can easily filter all files under the /etc/dovecot/conf.d directory that ends with .conf and have been modified in the last five days with:

find /etc/dovecot/conf.d -name "*.conf" -mtime 5

Here is another example of filtering files based on the modification date using the -daystart option. The command below will list all files in the /home directory that were modified 30 or more days ago:

find /home -mtime  30 -daystart

Find Files by Permissions

The -perm option allows you to search for files based on the file permissions.

For example, to find all files with permissions of exactly 775 inside the /var/www/html directory, you would use:

find /var/www/html -perm 644

You can prefix the numeric mode with minus - or slash /.

When slash / is used as the prefix, then at least one category (user, group or others) must have at least the respective bits set for a file to match.

Consider the following example command:

find . -perm /444

The above command will match all the files with read permissions set for either user, group or others.

If minus - is used as the prefix then for the file to match at least the specified bits must be set. The following command will search for files that have read and write permission for the owner and group and are readable by other users:

find . -perm -664

Find Files by Owner

To find files owned by a particular user or group, use the -user and -group options.

For example, to search for all files and directories owned by the user linuxize, you would run:

find / -user linuxize

Here is a real-world example. Let’s say you want to find all files owned by the user www-data and change the ownership of the matched files from www-data to nginx:

find / -user www-data -type f  -exec chown nginx {} ;

Find and Delete Files

To delete all matching files, append the -delete option to the end of the match expression.

Make sure you are using this option only when you are confident that the result matches the files that you want to delete. It is always a good idea to print the matched files before using the -delete option.

For example to delete all files ending with .temp from the /var/log/ you would use:

find /var/log/ -name `*.temp` -delete

Use the -delete option with extreme caution. The find command line is evaluated as an expression and if you add the -delete option first, the command will delete everything below the starting points you specified.

When it comes to directories, find can delete only empty directories same as rmdir.

Conclusion

We have shown you how to use the find command with various options and criteria.

This article should give you a fundamental understanding of how to locate files on your Linux systems. You may also visit the find man page and read about all other powerful options of the find command.

If you have any questions or remark, please leave a comment below.

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