[手动选题][tech]: 20230228.3 ⭐️ Terminal Basics Series 3 Listing the Contents of Directory With ls Command.md (#28748)

sources/tech/20230228.3 ⭐️ Terminal Basics Series 3 Listing the Contents of Directory With ls Command.md

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+[#]: subject: "Terminal Basics Series #3: Listing the Contents of Directory With ls Command"
+[#]: via: "https://itsfoss.com/list-directory-content/"
+[#]: author: "Abhishek Prakash https://itsfoss.com/author/abhishek/"
+[#]: collector: "lkxed"
+[#]: translator: " "
+[#]: reviewer: " "
+[#]: publisher: " "
+[#]: url: " "
+
+Terminal Basics Series #3: Listing the Contents of Directory With ls Command
+======
+
+The ls command in Linux is used for listing the contents of directories. You can think of `ls` as a short form for `list`.
+
+![ls command output][1]
+
+There is more to just listing what a directory consists of. You can see the file size, the time it was created, whether it is a file or directory, and file permissions. You can even sort the output based on those criteria.
+
+I won't go into a lot of detail. You should know just enough basics to get your way around it at this stage.
+
+### Prepare your test setup
+
+This Terminal Basics tutorial series uses a hands-on approach where you learn things by doing them. It will be better to create a working scenario on your system so that you can try things and see similar results, as shown in this tutorial.
+
+Open a terminal and switch to the home directory and create a `ls-command` directory under the `practice` directory and then enter this newly created directory.
+
+```
+cd ~
+mkdir -p practice/ls-command
+cd practice/ls-command
+```
+
+**It's okay if you don't recognize some commands here. Just enter them as it is shown.**
+
+Create a couple of empty files:
+
+```
+touch empty_file_{1,2}
+```
+
+Copy a huge text file:
+
+```
+cp /etc/services .
+```
+
+Create a few directories:
+
+```
+mkdir dir_{1..3}
+```
+
+Create a hidden file:
+
+```
+echo "Now You See Me" > .john-cena
+```
+
+And let's end the setup with a soft link (like a shortcut to a file):
+
+```
+ln -s services link_services
+```
+
+Let's see how the ls-command directory looks now:
+
+```
+[email protected]:~/practice/ls-command$ ls
+dir_1  dir_2  dir_3  empty_file_1  empty_file_2  link_services  services
+```
+
+### Long list: Listing with details
+
+While the ls command shows the content, it doesn't give any details about the contents.
+
+This is where you can use the long listing option `-l`.
+
+```
+ls -l
+```
+
+It will show the directory's contents in individual rows with additional information in alphabetical order:
+
+![Long listing with ls command in Linux][2]
+
+📋
+
+Most Linux distros have preconfigured to show files, directories and links in different colors. The executable files are also shown in a different color.
+
+You'll see the following information in the long listing:
+
+- **File type**: - for file, d for directory, l for soft links.
+- **Number of hard links**: Usually 1 unless there is actually a hard link (don't worry too much about it).
+- **Owner name**: The user who owns the file.
+- **Group name:** The group that has access to the file.
+- **File size**: Size of the file in bytes. It is always 4K (or 4096) for the directories, irrespective of the directory size.
+- **Date and time**: Usually, the file's last modified time and date.
+- **Filename**: Name of the file, directory, or link .
+
+![File details in the long listing of ls command][3]
+
+It is a good idea to know about file permission and ownership. I highly recommend reading this tutorial.
+
+### Displaying the hidden files
+
+Remember that you created a 'hidden file' named .john-cena? But you don't see it in the output of the ls command.
+
+In Linux, if a filename starts with a dot (.), the file or directory is hidden from the normal view.
+
+To see these 'hidden files', you have to use the option `-a`:
+
+```
+ls -a
+```
+
+Actually, you can combine more than one option together in most Linux commands. Let's combine it with the long listing option:
+
+```
+ls -la
+```
+
+Now, it will show the hidden .john-cena file:
+
+![Show hidden files with ls command in Linux][4]
+
+Did you notice the special directories `.`(current directory) and `..`(parent directory) are also displayed now?
+
+You can make them go away and still show other hidden files using the option `-A` instead of `-a`. Go ahead and try it.
+
+### Display file size
+
+The long listing option `-l` shows the file size. However, it is not easy to understand. For example, in the examples above, the services file has size 12813 bytes.
+
+As a normal computer user, it makes more sense to see the file size in KB, MB and GB.
+
+The ls command has a human-readable option `-h`. Combine it with the long listing option and you can see the file size in recognizable formats.
+
+![Showing file size with the ls command][5]
+
+💡
+
+The ls command doesn't display the size of directories. For directory size, you have the 
+
+```
+du
+```
+
+ command.
+
+### Display the newest files first
+
+You already saw that the long listing shows the modified time of a file/directory.
+
+You can sort the output of the ls command based on this timestamp using the `-t` option:
+
+```
+ls -lt
+```
+
+As you can see, the link was the most recent of them all.
+
+![Sort files on modified time in Linux][6]
+
+🖥️
+
+Reverse the order and show older files first by combining the above option 
+
+```
+-t
+```
+
+ with the reverse option 
+
+```
+-r
+```
+
+. What do you see?
+
+### Show details on individual files
+
+So far, you have used the ls command on the entire current directory. You can also use it on a single file or a bunch of files and directories. What's the point? Well, you can use the long listing option to get the details on selected files.
+
+```
+ls path_to_file1 path_to_file2
+```
+
+Here's an example:
+
+![Using ls commandon selected files][7]
+
+🏋️
+
+If you use the 
+
+```
+ls
+```
+
+ command with a directory path, it will show its content. If you want to see the stats of a directory, use the option 
+
+```
+-d
+```
+
+.
+
+### Test your knowledge
+
+Most Linux commands have numerous options. It is impossible for anyone to know them all, even for the most frequently used commands like ls here.
+
+For now, you have a decent idea about listing the contents of a directory and checking file stats. It's time to put your knowledge to some test.
+
+Try the following:
+
+- Create a new directory called ls_exercise and enter this directory
+- Use the following command to copy a file: `cp /etc/passwd .`
+- Check the content of a directory. What's the filename?
+- What is the size of this file?
+- Copy some more files using this command: `cp /etc/aliases /etc/os-release /etc/legal .`
+- Sort the files in the reverse order of modified time.
+- What do you observe if you run the following command: `ls -lS`?
+
+You can discuss this exercise in the community forum.
+
+In the next chapter of the Terminal Basics series, you'll learn about creating files in Linux command line.
+
+Do let me know if you have questions or suggestions.
+
+--------------------------------------------------------------------------------
+
+via: https://itsfoss.com/list-directory-content/
+
+作者：[Abhishek Prakash][a]
+选题：[lkxed][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://itsfoss.com/author/abhishek/
+[b]: https://github.com/lkxed/
+[1]: https://itsfoss.com/content/images/2023/02/ls-command-sample-output.png
+[2]: https://itsfoss.com/content/images/2023/02/ls-command-long-listing.png
+[3]: https://itsfoss.com/content/images/2023/02/file-permission-explanation.webp
+[4]: https://itsfoss.com/content/images/2023/02/showing-hidden-files-with-ls-command.png
+[5]: https://itsfoss.com/content/images/2023/02/show-file-size-with-ls.png
+[6]: https://itsfoss.com/content/images/2023/02/ls-sort-by-time.png
+[7]: https://itsfoss.com/content/images/2023/02/ls-command-on-some-files.png