19 Powerful Ways to Use the ls Command in Linux

The ls command in Linux is likely the first command you’ll encounter when you start using the Linux command prompt. Despite its frequent use, many users may not be fully aware of all the tricks and options available with the “ls” command. This guide will provide you with a detailed understanding of the “ls” command, from basic usage to advanced options.

Exploring Files and Directories

When you run the ls command in Linux systems without any options, it displays files and directories in a simple format. This basic usage doesn’t provide details like file types, size, modification date and time, permissions, and links.

$ ls

file1.txt  file2.txt  directory1  directory2

Recursive Listing of Files

The -R option in the ls command stands for “recursive”. When used with ls, it displays the contents of directories recursively, meaning it will list all files and sub-directories within the specified directory, as well as the contents of any sub-directories within those directories, and so on.

By default, the ls command only displays the direct contents of the specified directory. However, if you want to see the contents of all sub-directories as well, you can use the -R option.

$ ls -R

.:
file1.txt  file2.txt  directory1  directory2

./directory1:
file3.txt  subdirectory1

./directory1/subdirectory1:
file4.txt

In this example, ls -R first lists the contents of the current directory (.), then the contents of directory1, and finally the contents of subdirectory1 within directory1. This continues for all sub-directories within the specified directory.

Detailed Listing of Files

By using the “-l” option with the “ls” command, you can view a long listing format that provides additional details about the files and directories. It provides details such as file permissions, number of links, owner, group, size, and last modification time.

$ ls -l

-rw-r--r-- 1 user group 100 May 26 10:00 file1.txt
-rw-r--r-- 1 user group 984 May 26 10:00 file2.txt
drwxr-xr-x 2 user group 4096 May 26 10:00 directory1
drwxr-xr-x 2 user group 4096 May 26 10:00 directory2

Each part in the above output has a specific meaning. The following points describe each column respectively:

1. File Type and Permissions: The first character indicates the type of file. It can be - for a regular file, d for a directory, l for a symbolic link, etc. The next nine characters are divided into three sets, each representing the permissions for the user (owner), group, and others, respectively. Each set consists of three types of permissions: read (r), write (w), and execute (x). If a permission is not set, a dash (-) is shown.
2. Number of Links: This field shows the number of hard links to the file or directory. A hard link is essentially a reference or pointer to the file’s physical location on the disk.
3. Owner of the File: This field indicates the username of the file’s owner. The owner is the user who has the authority to change the permissions of the file.
4. Group of the File: This field indicates the group that owns the file. Users who are part of this group will have the same access permissions to the file as those granted to the group.
5. Size of the File: This field shows the size of the file or directory in bytes.
6. Last Modification Time: This field indicates the last time the file or directory was modified. It shows the date and time of the last modification.
7. File or Directory Name: The last field is the name of the file or directory.

Showing Hidden Files

The -a option in the ls command stands for “all”. When used with ls, it displays all files in the directory, including hidden files.

In Linux and Unix-like systems, any file or directory that starts with a dot (.) is considered hidden. These hidden files are often used to store configuration settings for different programs. By default, the ls command does not display these hidden files.

When you use the -a option, ls -a, it includes these hidden files in the output.

$ ls -a

.  ..  .hiddenfile  file1.txt  file2.txt  directory1

Displaying Files in a Human-Readable Format

The -h option in the ls command stands for “human-readable”. When used with ls -l, it displays file sizes in a format that is easier to understand for humans. By default, ls -l displays file sizes in bytes.

When you use the -h option, ls -l -h or ls -lh, it automatically converts file sizes into kilobytes (K), megabytes (M), gigabytes (G), or terabytes (T), depending on the size of the file. For instance, a file size might be displayed as 23M instead of 23197794, making it much easier to understand.

$ ls -lh

-rw-r--r-- 1 user group 2K May 26 10:00 file1.txt
-rw-r--r-- 1 user group 8K May 26 10:00 file2.txt
drwxr-xr-x 2 user group 4.0K May 26 10:00 directory1
drwxr-xr-x 2 user group 4.0K May 26 10:00 directory2

Sorting Files by Modification Time

When you use the -t option with the ls command in Linux systems it sorts files and directories based on their modification time, in the order of their last modification, with the most recently modified files or directories displayed first.

By default, the ls command sorts and displays files and directories in alphabetical order. However, there are situations where you might want to see the files that were most recently modified. This is where the -t option comes in handy.

$ ls -lt

-rw-r--r-- 1 user group 0 May 26 10:01 file2.txt
-rw-r--r-- 1 user group 0 May 26 10:00 file1.txt
drwxr-xr-x 2 user group 4096 May 26 09:59 directory2
drwxr-xr-x 2 user group 4096 May 26 09:50 directory1

Reverse Sorting of Files

The -r option tells ls to reverse the order of the sort. When used in conjunction with -t, it causes ls to display the files and directories in reverse chronological order, meaning the oldest modified files or directories are displayed first.

So, when you use ls -ltr, it displays a detailed listing of files and directories, sorted by the time of the last modification, but in reverse order (oldest first).

$ ls -ltr

-rw-r--r-- 1 user group 1000 May 26 09:59 file1.txt
-rw-r--r-- 1 user group 200 May 26 10:00 file2.txt
drwxr-xr-x 2 user group 4096 May 26 10:01 directory1
drwxr-xr-x 2 user group 4096 May 26 10:02 directory2

Listing Files of a Specific Type

The ls command in Linux can be used to list files of a specific type using wildcards. This is particularly useful when you want to filter the output of ls to only show files with a certain extension.

For example, if you want to list all text files in a directory, you can use the *.txt wildcard with the ls command. The * character is a wildcard that matches any sequence of characters, and .txt specifies that you’re interested in files that end with .txt.

$ ls *.txt

file1.txt  file2.txt  file3.txt

In this example, ls *.txt lists all files in the current directory that end with .txt. You can replace .txt with any other file extension to list files of that type. For example, ls *.jpg would list all JPEG image files, and ls *.py would list all Python script files.

Listing Files with Multiple Conditions

The ls command in Linux can be used to list files that meet multiple conditions using wildcards and braces {}. This is useful when you want to filter the output of ls to show files with certain extensions or patterns.

For example, if you want to list all .jpg and .png files in a directory, you can use the {} braces with the ls command. Inside the braces, you specify the conditions separated by commas. The * character is a wildcard that matches any sequence of characters.

$ ls *.{jpg,png}

image1.jpg  image2.jpg  image3.png  image4.png

In this example, ls *.{jpg,png} lists all files in the current directory that end with .jpg or .png.

You can replace jpg,png with any other file extensions to list files of those types. For example, ls *.{txt,docx} would list all text and Word document files. This is a powerful way to filter and list files based on multiple conditions.

Listing Files by File Size

The -S option is used to list files sorted by file size. This is useful when you want to quickly find the largest or smallest files in a directory. The -S option tells ls to sort the files and directories by size, with the largest files displayed first.

$ ls -lS

-rw-r--r-- 1 user group 5000 May 26 10:00 largefile.txt
-rw-r--r-- 1 user group 3000 May 26 10:00 mediumfile.txt
-rw-r--r-- 1 user group 1000 May 26 10:00 smallfile.txt

Displaying File Sizes in KB, MB etc

The --block-size option can be used to display file sizes in a more human-readable format. This is particularly useful when dealing with large files, as it allows you to easily see the size of the file in kilobytes (K), megabytes (M), gigabytes (G), etc., rather than in bytes.

For example, if you want to display file sizes in megabytes, you can use the --block-size=M option with the ls command. The --block-size=M option tells ls to display the file sizes in megabytes.

$ ls -l --block-size=M

-rw-r--r-- 1 user group 0M May 26 10:00 smallfile.txt
-rw-r--r-- 1 user group 5M May 26 10:00 mediumfile.txt
-rw-r--r-- 1 user group 1024M May 26 10:00 largefile.txt
-rw-r--r-- 1 user group 1048576M May 26 10:00 hugefile.txt

smallfile.txt - This file is less than 1MB, so it appears as 0M
largefile.txt - This file is 1GB, which is 1024MB
hugefile.txt - This file is 1TB, which is 1048576MB

Displaying Directory Information

The -d option can be used to display information about a directory itself, rather than its contents. This is useful when you want to check the permissions, ownership, size, or modification time of the directory itself.

By default, when you use the ls command with a directory, it lists the contents of the directory. However, if you want to display information about the directory itself, you can use the -d option with the ls command.

$ ls -ld /home/user

drwxr-xr-x 2 user group 4096 May 26 10:00 /home/user

In this example, ls -ld /home/user displays information about the /home/user directory itself, not its contents. The output shows that /home/user is a directory (d in the first position), the user user has read, write, and execute permissions on it, the group group has read and execute permissions, and others have read and execute permissions. The directory contains 2 entries (the 2 after the permissions), it’s 4096 bytes in size, and it was last modified at 10:00 on May 26.

Listing Files with SELinux Context

The -Z option can be used to display the SELinux (Security-Enhanced Linux) context of files and directories. This is particularly useful on systems where SELinux is enabled, as it provides additional security information about each file and directory.

SELinux is a security module for the Linux kernel that provides a mechanism for supporting access control security policies. It includes a set of SELinux-specific file and process attributes, known as the SELinux context.

The -Z option tells ls to display the SELinux context in the long listing format. This includes the user, role, type, and optionally, the level of each file and directory.

$ ls -lZ

-rw-r--r--. 1 user group unconfined_u:object_r:user_home_t:s0 0 May 26 10:00 file1.txt

In this example, ls -lZ displays the SELinux context

unconfined_u:object_r:user_home_t:s0 for file1.txt.

This context indicates that the file is in the user_home_t type and is associated with the unconfined_u user and the object_r role. The s0 is the MLS/MCS security level.

This information can be useful for troubleshooting SELinux-related issues and for understanding the security implications of file and directory permissions on a system with SELinux enabled.

Displaying File Inode Number

The -i option displays the inode number of files and directories. This can be particularly useful for system administration tasks and file system management.

An inode (index node) is a data structure on a filesystem on Linux and other Unix-like operating systems that contains information about a file or directory. This includes attributes such as the file’s size, owner, device node, socket, pipe, etc., as well as the location of the file’s data. Each file or directory has a unique inode number within the filesystem. The -i option tells ls to display the inode number in the long listing format.

$ ls -li

1234567 -rw-r--r-- 1 user group 0 May 26 10:00 file1.txt

In this example, ls -li displays the inode number 1234567 for file1.txt. This number is unique to file1.txt within the filesystem and can be used for various file management tasks. For instance, some commands allow you to manipulate files directly through their inode number, which can be useful in cases where a file has special characters or other issues that make it difficult to handle with standard commands.

Listing Files Without Owner or Group

The -g option can be used to display a long listing format without the owner. This is similar to -l, but does not display the owner name.

$ ls -lg

-rw-r--r-- 1 group 0 May 26 10:00 file1.txt

The -G option can be used to display a long listing format without the group. This is similar to -l, but does not display the group name.

$ ls -lG

-rw-r--r-- 1 user 0 May 26 10:00 file1.txt

Listing Files Sorted by Extension

The ls command in Linux can be used to list files sorted by file extension using the -X option. This can be particularly useful when you have a directory with many different types of files and you want to group them by file type.

By default, the ls command sorts and displays files and directories in alphabetical order. However, if you want to sort the files by their extension, you can use the -X option.

$ ls -lX

-rw-rw-r--  1 user group   42094 Mar 22 14:37 test.html
-rw-r--r--  1 user group  972400 Mar  9 12:36 app.log
-rw-rw-r--  1 user group   16849 Mar 22 13:50 error.png
-rw-rw-r--  1 user group  121224 May 18 17:53 resume.pdf

Listing Files Sorted by Last Access Time

The -u and -lt options can be used to list files sorted by the time of last access. This can be particularly useful when you want to see which files were recently accessed.

By default, the ls -l command displays a long listing format that includes the time of last modification. However, if you want to sort the files by the time of last access, you can use the -u option. The -lt options tell ls to display a long listing format sorted by time, with the most recently accessed files displayed first.

$ ls -ltu

-rw-r--r-- 1 user group 0 May 26 10:01 recentAccess.txt
-rw-r--r-- 1 user group 0 May 26 10:00 lessRecentAccess.txt

The recentAccess.txt file is displayed first because it was the most recently accessed file.

Listing Files Sorted by Status Change Time

The -c and -lt options can be used to list files sorted by the time of last status change. This can be particularly useful when you want to see which files had their metadata (like permissions or ownership) changed recently.

The -lt options tell ls to display a long listing format sorted by time, with the most recently changed files displayed first. However, if you want to sort the files by the time of last status change, you can use the -c option.

$ ls -ltc

-rw-r--r-- 1 user group 0 May 26 10:01 recentChange.txt
-rw-r--r-- 1 user group 0 May 26 10:00 lessRecentChange.txt

Listing Files with Full Time, Including Seconds

Using the --full-time option we can list files with full time. This can be particularly useful when you need a precise timestamp for each file. The --full-time option tells ls to display the full time, including the date, hour, minute, and second of the last modification.

$ ls --full-time

-rw-rw-r--  1 user group  16849 2023-03-22 13:50:19.713603583 +0530 app.log

Conclusion

The ls command in Linux is a fundamental tool, providing a powerful means to list and inspect files and directories. Its versatility, from basic listings to advanced sorting and filtering, makes it an essential command for anyone navigating the Linux file system. Whether you’re a system administrator, a developer, or a casual user, mastering the ls command can significantly enhance your efficiency and productivity in managing files and directories.