Linux ls Command: An Insider’s Guide with 10 Practical Examples

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The ls command is one of the first commands a user learns when they start using a Linux machine.

The ls command, short for list, is a fundamental tool used for navigating directories and files. It provides a rundown of directories and various file types within the current working directory. 

Although ls is not a complicated command, it does come with a number of options for listing files with additional information.

In this tutorial, we will guide you through the fundamentals of the ls command along with practical examples that highlight its application in several real-world scenarios.

Table Of Contents

  1. The syntax of the ls command
    1. Using Options for the ls Command
  2. 10 Practical Examples of the ls Command
    1. The Prerequisites
    2. Example #1: Display Sort Options
    3. Example #2: Display Hidden Files
    4. Example #3: Display Directory Trees
    5. Example #4: Display Information in Long Listing Format
    6. Example #5: List UID and GID of Files
    7. Example #6: View File Sizes in Human Readable Format
    8. Example #7: Display Output Reversed by Date
    9. Example #8: List Files by Size
    10. Example #9: View Files Within the /tmp Directory
    11. Example #10: Display All ls Command Options
  3. Conclusion
  4. FAQs

The syntax of the ls command

ls command is a Linux shell command that lists the contents of files and directories.

The basic syntax of the ls command is:

# ls [options]

Here,

[options] allows you to incorporate additional instructions into the ls command. 

Some of the frequently used ls command options are:

the syntax of the ls command

The most basic form of the ls command does not utilize any options. It displays files and directories in a simple, bare-bones format. 

To execute the command, run the following in the terminal:

# ls 

ls

Using Options for the ls Command

The ls command is not just limited to the basic listing. You can use several options with the command to extend its basic capability. 

Let’s run through some common options that enhance functionality and flexibility of the command

The ls -F command appends a slash (/) at the end of each directory name. This command helps distinguish directories from files in the command output.

# Is -F 

Is -F

The ls -m command displays directories and files separated by commas.

Run the following command to display directories and files separately in the terminal:

# Is-m 

Is-m

The ls -Q command encloses all directories and files in quotation marks.

# ls -Q 

ls -Q

You can run the following command to obtain the Inode (index node) numbers of all directories and files:

# ls -i 

ls -i

10 Practical Examples of the ls Command

We will now run through some practical examples of using the ls command in Linux to display relevant information about the files and directories.

The Prerequisites

Before diving into the details of ls command, ensure you have the following:

  • A system running a mainstream Linux distribution
  • A use account with sudo or administrator privileges

Example #1: Display Sort Options

The ls command is a powerful tool for navigating file systems in Linux. One of its valuable features is the ability to sort the output of file listing based on different criteria. 

Let’s consider the following three popular scenarios:

Reverse Alphabetical Order

The ls -r sorts directories and files in reverse order, alphabetically by default. 

The command syntax is as follows:

# ls -r 

ls -r

Time

Use the ls -t command to sort directories and files based on their creation or modification time and date. The file or directory that was most recently modified will be listed first, followed by those modified earlier.

# Is -t

Is -t

Sort by Extension 

ls -X sorts the output alphabetically by file extension. This can be helpful when you work with multiple file types and want to sort files of a particular type.

To sort files and directories based on extension, run:

# ls -X

ls -X

Example #2: Display Hidden Files

The ls command, by default, hides files and directories of those that begin with a dot. These hidden files often contain system configuration or user-specific settings. However, there are times when you need to view these hidden files.

To display hidden files, run:

# ls -a

The output displays all files and directories, including those with a dot.

ls -a

You can also run the following command to obtain a comprehensive list of hidden files:

# ls -la

The standard output furnishes details regarding the user, file size, and modification date and time.

ls -la

Example #3: Display Directory Trees 

The ls command is often a go-to command for navigating directory structures. The Directory Tree is a powerful Linux filesystem feature that displays a hierarchical listing of directories and their contents.

To display the directory tree, run:

# ls -R

ls -R

To display detailed information on the directory tree, including the owner of the file, size, and date and time of the last modification, combine -R with -I and execute:

# ls -IR

The output produces a long listing format for the entire directory tree, including subdirectories.

ls -IR

Example #4: Display Information in Long Listing Format

The ls -l command generates a long listing format of files and directories in the current directory. The standard output includes details such as the file or folder name, file owner, size, and modification date and time.

To display a long listing format for the files and directories, run:

# ls -l

ls -l

Example #5: List UID and GID of Files

ls -n displays the user ID (UID) and group ID (GID) for the owner and group of each file. These numerical IDs are used internally by the system and are also helpful for advanced file system management tasks.

To display user ID and group ID, run this command in the terminal:

# ls -n

ls -n

Example #6: View File Sizes in Human Readable Format

ls -lh displays file sizes in a more human-readable format, such as kilobytes (KB), megabytes (MB), or gigabytes (GB), instead of bytes, making it easier to understand the size of files.

To check the size of files and directories in a human-readable format, run the following command:

# ls -lh

ls -lh

Example #7: Display Output Reversed by Date

ls -ltr displays a detailed listing of files and directories, sorted by their modification date and time with the most recently modified files and directories appearing first.

Here, 

  • -l denotes long listing
  • -t denotes sort by modification time
  • -r denotes reverse order.

The following command reverse sort the output by date and time:

# ls -ltr

ls -ltr

Example #8: List Files by Size

The default behavior of the ls command is to list the files and directories in the default order. However, you may wish to see the files ordered by size. In these cases, we recommend the 

ls -lS command that displays a long listing format with the files sorted by size, from largest to smallest.

The command syntax in this case will be as follows: 

# ls -lS

ls -lS

Example #9: View Files Within the /tmp Directory

ls -l /tmp will display a detailed listing of the contents in the /tmp directory on your Linux system.

Run the following command to display a detailed listing of the contents in the temporary directory (/tmp):

# ls -l /tmp

ls -l tmp

A slight modification of this command, ls -ld /tmp/ displays information about the /tmp/ directory, excluding the contents. The syntax of this command is as follows: 

# ls -ld /tmp/

ls -ld tmp

Example #10: Display All ls Command Options

Most Linux distributions support ls –help as a general command syntax that provides comprehensive information about the various options. In addition, you can read about the exit codes and relevant information about the command’s behavior. 

# ls --help

ls --help

Conclusion

By now, you know how to use the most important ls commands in Linux, allowing you to navigate files and directories effectively. As you continue your Linux journey, mastering ls commands empowers you to interact with your file system more efficiently and provides valuable insights into your data.

FAQs

Q. What is an executable file and how does it relate to file names? 

An executable file in Linux is a type of file that can be run or executed to perform a specific task. These files typically have permissions set to allow execution. File names in Linux can consist of a combination of letters, numbers, and special characters. They serve as unique identifiers for files within a directory.

Q. What information does the file size represent in bytes and how does it relate to the current working directory? 

The file size, measured in bytes, indicates the amount of storage space a file occupies on a storage device. This size can vary depending on the contents and format of the file. The current working directory refers to the directory in which a user works within the file system.

Q. What are directory permissions and how do they relate to special files and file systems?

Directory permissions in Linux, control access to directories, determining who can view, modify, or execute files within them. Certain files in Linux represent various system resources, such as devices and network connections, and interact with file systems differently than normal files. Understanding these concepts is essential for effective file management and system administration.

Q. What constitutes a simple command in Linux, and how does it relate to file list format and size in bytes? 

In Linux, a simple command refers to a single instruction or task issued at the command line. List format in Linux refers to the structured display of file information, typically organized into columns. Size in bytes represents the amount of storage space a file occupies on a storage device, providing insight into its scale and resource consumption.

Q. How do the characters in file names affect sorting files, and what do the first and second columns represent in file lists? 

Characters in file names can impact the sorting order of files, especially when using alphabetical sorting methods. The first column in file lists typically represents the file permissions and attributes, while the second column often denotes the number of links to the file.

Q. What are the different types of files listed in Linux, and how is file size displayed in list format? 

Linux lists various types of files, including regular files, directories, symbolic links, and special files such as device files. File size in list format is typically displayed in bytes, precisely measuring each file’s storage footprint.

Q. What information does the owner column provide in file listings, and how are character positions relevant in file management? 

The owner column in file listings identifies the user who owns the file or directory, indicating the primary user with privileges over it. Character positions in file management refer to the specific locations within a file’s name or content, influencing how files are accessed and manipulated.

Q. What are character special and block special files, and how do they relate to indirect blocks and the count of blocks? 

Character special files and block special files in Linux represent different types of device files used to interact with hardware devices. Indirect blocks and the count of blocks are concepts related to file system management, particularly in managing file storage allocation and retrieval.

Q. How can I navigate deep directory trees efficiently in Linux, and what are some common command examples for file and directory management?

Navigating deep directory trees in Linux involves utilizing commands such as cd to change directories and ls to list the contents of directories. Common command examples for file and directory management include cp for copying files, mv for moving files, and rm for removing files. Understanding these commands is essential for performing tasks on a regular basis and efficiently managing the contents of directories.

Q. What is the significance of file size in bytes, and how are file extensions utilized in file management? 

File size in bytes indicates the amount of storage space a file occupies on a storage device, providing insight into its scale and resource consumption. File extensions in file management identify a file’s type or format, aiding in its organization and compatibility with specific applications.

Q. What role do configuration files play in Linux systems, and how are directory listings structured to display a list of files? 

Configuration files in Linux contain settings and parameters that configure the behavior of various system components and applications. Directory listings are structured to display a list of files and directories within a specified directory, typically arranged in alphabetical or chronological order.

Q. How can I sort files in Linux by default, and what size format is used to display file sizes in directory listings? 

Files in Linux are sorted by default based on alphabetical order or by modification time, depending on the command used. The size format used to display file sizes in directory listings is typically in bytes, providing a precise measurement of each file’s storage footprint.

Q. What does it mean for a file to be considered ordinary, and how are file entries displayed in directory listings? 

An ordinary file in Linux contains data or information, such as text files, documents, or program executables. Entries for files in directory listings represent individual files within a directory, providing information about their attributes and permissions.

Q. What distinguishes a regular directory from other directories, and how can I list files within a directory? 

A regular directory in Linux is a standard directory containing files and subdirectories. To list files within a directory, you can use commands such as ls to display a list of files and directories in the current working directory or specify a different directory to list its contents.

 

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