Part 2 [echo & ls] - Know your commands

Hey folks, this is part 2 of the series Know your commands.

If you are new here, please also checkout the other parts of this series.

• Part 1 - pwd & cd
• Part 2 - echo & ls
• Part 3 - touch & mkdir

In this part I will be covering the use of echo and ls commands.

echo #

echo command is used to output the strings that is being passed as an argument.

Syntax

echo [optional flag] [string]

Usage

$ echo "This will be print to the console"
This will be print to the console

ls #

ls stands for List. It is used to list the files and folders in current working directory.

Syntax:

ls [optional flags] [optional directory]

Usage:

$ pwd
/home/subin

$ ls
Desktop
Documents
Downloads
Music
Pictures

• ls [folder_path] - This command lists the files and folders in the specified path. The folder_path can be absolute or relative.

  $ pwd
  /home/subin
  
  $ ls Downloads
  movie
  

• ls -a - By default all files and folders that starts with . dot are hidden on your system. These files are hidden but yet it can be accessed by the system or any application installed. So don’t try to rename you Study material folder to start with a dot to escape from your parents 😉.

  

  These Dot Files are just plain text configuration files. These files can be listed using the flag -a.

  $ pwd
  /home/subin
  
  $ ls -a
  .bashrc
  .config
  Desktop
  Documents
  Downloads
  Music
  Pictures
  

• ls -l - This command provides a long list. Running this command will return folder and files with additional details lik permissions, owner, group, size, etc

  $ pwd
  /home/subin
  
  $ ls -l
  drwxrwxr-x 2 subin subin 4096 Nov  2 18:01 Desktop
  drwxrwxr-x 8 subin subin 4096 Oct 12 20:55 Documents
  drwxrwxr-x 3 subin subin 4096 Feb 10  2019 Downloads
  drwxrwxr-x 3 subin subin 4096 Feb 3  2019 Music
  drwxrwxr-x 3 subin subin 4096 Feb 7  2019 Pictures
  
  #Mutiple flags can be combined
  $ ls -la
  -rw-r--r--  1 subin subin 3488 Oct 20 2018 .bashrc
  drwx------  3 subin subin 4096 May 5  2018 .config
  drwxrwxr-x  2 subin subin 4096 Nov 2  2018 Desktop
  drwxrwxr-x  8 subin subin 4096 Oct 12 2018 Documents
  drwxrwxr-x  3 subin subin 4096 Feb 10 2019 Downloads
  drwxrwxr-x  3 subin subin 4096 Feb 3  2019 Music
  drwxrwxr-x  3 subin subin 4096 Feb 7  2019 Pictures
  

• Other popular ls commands

  Command	Description
  ls -lh	Long list with readable file size
  ls -R	Lists the directory tree recursively
  ls -r	Displays the list in Reverse order
  ls -s	Displays the list with File Size
  ls -S	The displayed list is sorted by File Size
  ls -t	The displayed list is sorted by Time & Data
  ls -x	The displayed list is sorted by Extension

• The above flags can be combined in multiple ways to build complex results.

What’s next #

As of now you should be familiar with pwd, cd, echo, ls, with these you should be able to comfortably navigate between the file system with ease. So why wait, let’s celebrate your accomplishment.

The next part of this series will focus on touch and mkdir commands. Stay tuned

Note: All examples above are based on below imaginary directory structure.

.
├── home
│   └── subin
│       ├── .bashrc
│       ├── .config
│       ├── Downloads
│       │   └── movie
│       │       └── some_movie.mp4
│       ├── Desktop
│       ├── Documents
│       │   └── test_doc.txt
│       ├── Music
│       └── Pictures
├── lib
├── opt
└── tmp