29.Find_Command_Usage.md

Find Command

The find command is used to locate files and directories in the file system. It offers more search options compared to the locate command, including:

1. Search only files
2. Search only directories
3. Search by name
4. Search by size
5. Use search results with other commands
6. Restrict search to a maximum depth

Usage

Basic Command

$ find

This command will find all files and directories in the current working directory and below in the Linux file system. This is the default behavior.

Finding Files and Directories

Specifying a Directory

You can find all files and directories in a specified directory and its subdirectories with the following commands:

$ find /dev
$ find /etc

Using the maxdepth Option

By default, the find command searches through all depth levels. However, you can limit the search to a specific depth using the -maxdepth option.

Directory Structure Example

Desktop
|- file1.txt
|- level_1_dir
   |- file2.txt
   |- level_2_dir
      |- file3.txt
      |- level_3_dir
         |- file4.txt
         |- level_4_dir
            |- file5.txt

To create this structure, you can use:

$ mkdir -p level_1_dir/level_2_dir/level_3_dir/level_4_dir
$ touch file1.txt level_1_dir/file2.txt level_1_dir/level_2_dir/file3.txt level_1_dir/level_2_dir/level_3_dir/file4.txt level_1_dir/level_2_dir/level_3_dir/level_4_dir/file5.txt

Output

akshay@myubuntu:~/Desktop$ mkdir -p level_1_dir/level_2_dir/level_3_dir/level_4_dir
akshay@myubuntu:~/Desktop$ tree
.
└── level_1_dir
    └── level_2_dir
        └── level_3_dir
            └── level_4_dir

5 directories, 0 files
akshay@myubuntu:~/Desktop$ touch file1.txt level_1_dir/file2.txt level_1_dir/level_2_dir/file3.txt level_1_dir/level_2_dir/level_3_dir/file4.txt level_1_dir/level_2_dir/level_3_dir/level_4_dir/file5.txt
akshay@myubuntu:~/Desktop$ tree
.
├── file1.txt
└── level_1_dir
    ├── file2.txt
    └── level_2_dir
        ├── file3.txt
        └── level_3_dir
            ├── file4.txt
            └── level_4_dir
                └── file5.txt

5 directories, 5 files

Observing the Difference in Results

Execute the following commands to see the effect of maxdepth:

1. $ find . -maxdepth 1

2. $ find . -maxdepth 2

3. $ find . -maxdepth 3

4. $ find . -maxdepth 4

5. $ find . -maxdepth 100

Output

akshay@myubuntu:~/Desktop$ find . -maxdepth 1
.
./level_1_dir
./file1.txt
akshay@myubuntu:~/Desktop$ find . -maxdepth 2
.
./level_1_dir
./level_1_dir/file2.txt
./level_1_dir/level_2_dir
./file1.txt
akshay@myubuntu:~/Desktop$ find . -maxdepth 3
.
./level_1_dir
./level_1_dir/file2.txt
./level_1_dir/level_2_dir
./level_1_dir/level_2_dir/level_3_dir
./level_1_dir/level_2_dir/file3.txt
./file1.txt
akshay@myubuntu:~/Desktop$ find . -maxdepth 4
.
./level_1_dir
./level_1_dir/file2.txt
./level_1_dir/level_2_dir
./level_1_dir/level_2_dir/level_3_dir
./level_1_dir/level_2_dir/level_3_dir/level_4_dir
./level_1_dir/level_2_dir/level_3_dir/file4.txt
./level_1_dir/level_2_dir/file3.txt
./file1.txt
akshay@myubuntu:~/Desktop$ find . -maxdepth 5
.
./level_1_dir
./level_1_dir/file2.txt
./level_1_dir/level_2_dir
./level_1_dir/level_2_dir/level_3_dir
./level_1_dir/level_2_dir/level_3_dir/level_4_dir
./level_1_dir/level_2_dir/level_3_dir/level_4_dir/file5.txt
./level_1_dir/level_2_dir/level_3_dir/file4.txt
./level_1_dir/level_2_dir/file3.txt
./file1.txt

Notes

1. The maxdepth option requires a single dash (-), not a double dash (--):

   • -maxdepth → Valid
   • --maxdepth → Invalid

2. The find command can also locate hidden files and directories.

Finding by Type

You can use the -type option with the find command to search for specific types of files:

• -type f → Find only files
• -type d → Find only directories

Examples

Finding Files

$ find -type f

Output might include:

./level_1_dir/file2.txt
./level_1_dir/level_2_dir/file3.txt
./level_1_dir/level_2_dir/level_3_dir/level_4_dir/file5.txt
./level_1_dir/level_2_dir/level_3_dir/file4.txt
./file1.txt
./.securefile1.txt

Finding Directories

$ find -type d

Output might include:

.
./.db_info
./level_1_dir
./level_1_dir/level_2_dir
./level_1_dir/level_2_dir/level_3_dir
./level_1_dir/level_2_dir/level_3_dir/level_4_dir

Important Note

You can use these options simultaneously, but the order matters. Always specify -maxdepth before -type:

• $ find -type f -maxdepth 2  # Generates a warning

• $ find -maxdepth 2 -type f  # No warnings

Finding by Name

To find files and directories by name, use the -name option.

Examples

1. Create test files:

   $ touch {A..D}.txt
   $ touch {A,B}{A,B}.txt

2. Search for files by name:

   $ find . -name 'A.txt'

3. Use wildcards for more complex searches:

   $ find . -name '?.txt'
   $ find . -name '??.txt'
   $ find . -name '*.txt'
   $ find . -maxdepth 2 -name '*.txt'

Case-Insensitive Search

If you want to ignore case when searching, use the -iname option:

$ find -iname 'a.txt'

Finding Files by Size

To find files based on their size, you can use the -size option with the find command.

Size Modifiers

• +n → greater than n
• -n → less than n
• n → exactly n
• -empty → find empty files or directories

Examples

1. List all file names where size is over 200 KB:

   $ find / -type f -size +200k

   This command requires root privileges.

   To count the files, use:

   $ sudo find / -type f -size +200k | wc -l

2. List all file names where size is over 200 KB but less than 4 MB:

   $ find / -type f -size +200k -size -4M | wc -l

3. List all file names where file size is less than 200 KB or more than 4 MB:

   $ find / -type f -size -200k -o -size +4M | wc -l

   Here, -o means "or."

Q1: Output of the Following Command

$ find / -type f -size -200k -size +4M | wc -l

The answer should be: 0

Using Search Results of Find Command

You can perform operations on the results of the find command using the -exec option.

• Example: To copy all files in the /etc folder where file size is less than 2 KB to the dir1 directory on the Desktop:

  $ find /etc -type f -size -2k -exec cp {} dir1 \;

  Here, {} is a placeholder for the found files.

  If you want confirmation before executing the command, use the -ok option instead:

  $ find /etc -type f -size -2k -ok cp {} dir1 \;

This will prompt you for confirmation before each copy operation.