4. ls (List Directories)

Now that we know how to move around the file system, how do we figure out what is available to us? Without the right tool, it's like moving around in the dark. Fortunately, the wonderful command linux ls is here to help by listing directory contents.

Basic Usage of the ls Command

By default, the ls command will list the directories and files in your current directory. However, you can also specify a path to list the contents of a different directory.

ls
ls /home/pete

The command ls is a versatile tool that can show you detailed information about the files and directories you are viewing.

Viewing Hidden Files

Note that not all files in a directory are visible by default. In Linux, filenames that start with a dot (.) are hidden. You can view them by using the cmd ls with the -a flag, which stands for "all".

ls -a

Getting Detailed Information

Another essential ls flag is -l for "long". This option provides a detailed list of files in a long format. This will show you detailed information, starting from the left: file permissions, number of links, owner name, owner group, file size, timestamp of last modification, and the file or directory name.

ls -l

Here is an example of the output:

pete@icebox:~$ ls -l
total 80
drwxr-x--- 7 pete penguingroup   4096 Nov 20 16:37 Desktop
drwxr-x--- 2 pete penguingroup   4096 Oct 19 10:46  Documents
drwxr-x--- 4 pete penguingroup   4096 Nov 20 09:30 Downloads
drwxr-x--- 2 pete penguingroup   4096 Oct  7 13:13   Music
drwxr-x--- 2 pete penguingroup   4096 Sep 21 14:02 Pictures
drwxr-x--- 2 pete penguingroup   4096 Jul 27 12:41   Public
drwxr-x--- 2 pete penguingroup   4096 Jul 27 12:41   Templates
drwxr-x--- 2 pete penguingroup   4096 Jul 27 12:41   Videos

Sorting in Reverse Order

Sometimes you may want to change the sort order. The ls -r command lists files and directories in reverse alphabetical order. The linux ls -r option is particularly handy when you want to see the last items in a long list first.

ls -r

Combining Command Flags

Commands have flags (also called arguments or options) to add more functionality. As we saw with -a and -l, you can combine them into a single command like ls -la. The order of the flags usually doesn't matter, so ls -al would work identically. You can also add the reverse flag: ls -lar.

ls -la