Book Image

Linux Shell Scripting Essentials

By : Sinny Kumari, Khem Raj
Book Image

Linux Shell Scripting Essentials

By: Sinny Kumari, Khem Raj

Overview of this book

Table of Contents (15 chapters)
Linux Shell Scripting Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Permission and ownership


As a user of a system, to access a file in Linux and UNIX, it is important that a user has the required permission for that specific file or directory. For example, as a regular user, perform cd into /root:

$ cd /root
bash: cd: /root/: Permission denied

We were not able to do so because of the permission denied error:

$ cd ~/

We were successfully able to do cd into the user's home directory because a user had the permission to access its own home directory.

Every file in UNIX or Linux has an owner and an associated group. It also has a set of permissions (read, write, and execute) with respect to the user, group, and others.

Viewing the ownership and permission of files

The ls command with the -l option is used to view the ownership and permission of a file:

$ touch permission_test_file.txt    #  Creating a file
$ ls -l  permission_test_file.txt    # Seeing files' attributes
-rw-rw-r-- 1 foo foo 0 Aug 24 16:59 permission_test_file.txt

Here, the first column of ls contains...