“ sudo”命令如何工作？

Question

My understand is that sudo is executes a given command with root privileges, but I experienced that entering a command in Terminal with sudo caches the authorization. How does it actually works?

For eg

sudo fdisk -l
[sudo] password for xxxxx:

(once I authorize by entering a password, successive sudo commands are not prompting for passwords)

sudo fdisk -l

(not prompting for password)

sudo mount -t vfat /dev/sda1 /media/test

Whether sudo is really a wrapper for su (substitute/switch user)?

Answer 1

man sudo would tell:

   Security policies may support credential caching to allow the user to
   run sudo again for a period of time without requiring authentication.
   The sudoers policy caches credentials for 15 minutes, unless overridden
   in sudoers(5).  By running sudo with the -v option, a user can update
   the cached credentials without running a command.

It also says:

   -k [command]
               When used alone, the -k (kill) option to sudo invalidates
               the user's cached credentials.  The next time sudo is run a
               password will be required.  This option does not require a
               password and was added to allow a user to revoke sudo
               permissions from a .logout file.  Not all security policies
               support credential caching.

               When used in conjunction with a command or an option that
               may require a password, the -k option will cause sudo to
               ignore the user's cached credentials.  As a result, sudo
               will prompt for a password (if one is required by the
               security policy) and will not update the user's cached
               credentials.

Answer 2

Here goes proper detail for you:
Yes sudo and su command is bit different:
1.) When we fire su command it will act as a pure Admin (We can same permanently for that session time)
2.) Whereas, sudo command is acts as a having or assigning admin priviledges (We can say temporary for that session only)

Another Example:
In windows system, hope you have checked right click properties like "Run as Administrator", this is same as sudo.
And if we login or switching user to Admin, it purely acts as a Administrator for all the programs.

Hope you have understood my example, this was best from my side

Answer 3

In your /etc/sudoers you can edit the sudo configuration.

There is a default timeout of authorization.

You can even assign some of your user using sudo without requirement of a password. Or some user once authorized, it won't require password until you logout your system.