Birmingham mumbai

Understanding the /etc/passwd and /etc/shadow files 
47
Using/etc/passwd 48
Using /etc/shadow 
49
Distributing default configuration files with /etc/skel 
53
Switching users 
55
Managing groups 
56
Managing passwords and password policies 
60
Locking and unlocking user accounts 
60
Setting password expiration information 
61
Setting a password policy 
63
Configuring administrator access with sudo 
65
Setting permissions on files and directories 
69
Viewing permissions 
69
Changing permissions 
72
Changing the ownership of objects 
75
Summary 76
Further reading 
76
Chapter 3: Managing Software Packages 
77
Understanding Linux package management 
78
Understanding the differences between Debian and Snap packages 
79
Debian packages 
80
Snap packages 
81
Installing and removing software 
83
Managing Debian packages with apt 
84
Managing Snap packages with snap 
87
Searching for packages 
89
Managing package repositories 
91
Adding additional repositories 
91
Adding Personal Package Archives 
93