How to use the command 'ls' (with examples)

The ’ls’ command is used to list the contents of a directory. It provides information about the files and directories within a specified directory. This article will cover several use cases of the ’ls’ command, showcasing different options and arguments that can be used to customize the output.

Use case 1: List files one per line

Code:

ls -1

Motivation: This use case is useful when you want to get a clear and compact list of files in a directory, with each file listed on a new line. It makes it easier to read and work with the file names.

Explanation: The ‘-1’ option is used to display each file on a separate line.

Example output:

file1.txt
file2.txt
file3.txt

Use case 2: List all files, including hidden files

Code:

ls -a

Motivation: Hidden files are files that start with a dot (e.g., .gitignore) and are not normally displayed by the ’ls’ command. This use case allows you to list all files, including those that are hidden.

Explanation: The ‘-a’ option is used to show all files, including hidden files.

Example output:

.
..
file1.txt
file2.txt
.gitignore

Use case 3: List all files, with trailing ‘/’ added to directory names

Code:

ls -F

Motivation: This use case is helpful when you need to distinguish between directories and regular files. It adds a trailing slash (/) character to directory names in the output, making it easier to identify them.

Explanation: The ‘-F’ option is used to add a trailing ‘/’ to directory names.

Example output:

file1.txt
file2.txt
directory1/
directory2/

Use case 4: Long format list of all files

Code:

ls -la

Motivation: Sometimes it is necessary to view detailed information about files in a directory, including permissions, ownership, size, and modification date. This use case provides a long format list of all files, giving comprehensive information.

Explanation: The ‘-l’ option is used to display detailed long format information, and the ‘-a’ option shows all files.

Example output:

drwxr-xr-x  2 user  group  4096 Jan 1 00:00 directory1
-rw-r--r--  1 user  group  1024 Jan 1 00:00 file1.txt
-rw-r--r--  1 user  group  2048 Jan 1 00:00 file2.txt

Use case 5: Long format list with size displayed using human-readable units

Code:

ls -lh

Motivation: This use case provides a long format list of all files, similar to the previous use case, but the size of files is displayed using human-readable units (KiB, MiB, GiB) instead of bytes. This makes it easier to understand the file sizes.

Explanation: The ‘-l’ option is used to display detailed long format information, and the ‘-h’ option is used to display file sizes using human-readable units.

Example output:

drwxr-xr-x  2 user  group  4.0K Jan 1 00:00 directory1
-rw-r--r--  1 user  group  1.0K Jan 1 00:00 file1.txt
-rw-r--r--  1 user  group  2.0K Jan 1 00:00 file2.txt

Use case 6: Long format list sorted by size (descending)

Code:

ls -lS

Motivation: Sorting files by size can help identify the largest or smallest files in a directory. This use case provides a long format list of all files, with sizes sorted in descending order.

Explanation: The ‘-l’ option is used to display detailed long format information, and the ‘-S’ option is used to sort files by size.

Example output:

-rw-r--r--  1 user  group  4.0K Jan 1 00:00 file2.txt
-rw-r--r--  1 user  group  2.0K Jan 1 00:00 file1.txt
drwxr-xr-x  2 user  group  4.0K Jan 1 00:00 directory1

Use case 7: Long format list of all files sorted by modification date (oldest first)

Code:

ls -ltr

Motivation: Sorting files by modification date can be useful when you want to identify the most recently modified or oldest files. This use case provides a long format list of all files, with files sorted by modification date in ascending order (oldest files first).

Explanation: The ‘-l’ option is used to display detailed long format information, the ‘-t’ option is used to sort files by modification date, and the ‘-r’ option is used to reverse the sort order.

Example output:

drwxr-xr-x  2 user  group  4096 Jan 1 00:00 directory1
-rw-r--r--  1 user  group  1024 Jan 1 00:00 file1.txt
-rw-r--r--  1 user  group  2048 Jan 1 00:00 file2.txt

Use case 8: Only list directories

Code:

ls -d */

Motivation: Sometimes you only need to list directories within a specific directory and ignore regular files. This use case allows you to do that by filtering out non-directory entries.

Explanation: The ‘-d’ option is used to only list directories, and the ‘*/’ argument is used to match only directories.

Example output:

directory1/
directory2/

Conclusion:

The ’ls’ command is a versatile tool for listing files and directories within a specified directory. It offers various options and arguments to customize the output, allowing users to view specific information or filter file entries based on their requirements. By understanding the different use cases of the ’ls’ command, users can efficiently navigate and manage files within a directory.