How To Use Linux Find Command.
In this article we will show you how to use find command.
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.
find Command Syntax
The general syntax for the find command is as follows:
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:
The option -L (options) tells the find command to follow symbolic links.
The /var/www (path…) specifies the directory that will be searched.
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 by the name of the file you are searching for.
For example, to search for a file named document.pdf in the /home/liviu directory, you would use the following command:
To run a case-insensitive search, change the -name option with -iname:
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 would type:
It is important to mention that you must either quote the pattern or escape the asterisk * symbol with backslash \ so that it doesn’t get interpreted by the shell when you use the wildcard character.
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 Files by Type
Sometimes you might need to search for specific file types such as regular files, directories, or symlinks. In Linux, everything is a file.
To search for files based on their type, use the -type option and one of the following descriptors to specify the file type:
f: a regular file
l: symbolic link
c: character devices
b: block devices
p: named pipe (FIFO)
For instance, to find all directories in the current working directory , you would use:
The common example would be to recursively change the website file permissions to 644 and directory permissions to 755 using the chmod command:
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)
w: two-byte words
The following command will find all files of exactly 1024 bytes inside the /tmp directory:
The find command also allows you to search for files that are greater or less than a specified size.
In the following example, we search for all files less than 1MB inside the current working directory. Notice the minus – symbol before the size value:
If you want to search for files with a size greater than 1MB, then you need to use the plus + symbol:
You can even search for files within a size range. The following command will find all files between 1 and 2MB:
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 has been modified in the last five days:
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 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:
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:
The above command will match all the files with read permissions set for either user, group, or others.
- 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 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 liviu-test, you would run:
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 and Delete Files
To delete all matching files, append the -delete option to the end of the match expression.
Ensure you are using this option only when you are confident that the result matches the files 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:
Use the -delete option with extreme caution. The find command 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 .
We have shown you how to use the find command with various options and criteria.