Answer Posted / rhino

Kernel Mode (System Mode) :

in this mode executing code has complete and unrestricted
access to the underlying hardware. It can execute any CPU
instruction and reference any memory address.

Kernel mode is generally reserved for the lowest-level,
most trusted functions of the operating system. Crashes in
kernel
mode are catastrophic; they will halt the entire PC.

When the CPU is in kernel mode, it is assumed to be
executing trusted software, and thus it can execute any
instructions
and reference any memory addresses (i.e., locations in
memory).

The kernel (which is the core of the operating system and
has complete control over everything that occurs in the
system)
is trusted software, but all other programs are considered
untrusted software.

Thus, all user mode software must request use of the kernel
by means of a system call in order to perform privileged
instructions, such as process creation or input/output
operations.


User Mode :

In User mode, the executing code has no ability to directly
access hardware or reference memory. Code running in user
mode must delegate to system APIs to access hardware or
memory.

Due to the protection afforded by this sort of isolation,
crashes in user mode are always recoverable. Most of the
code
running on your computer will execute in user mode.

What are awk commands?

583

---

What is the use of awk command in unix?

581

---

What does pipe () return?

596

---

What are the unix commands?

560

---

Enlist some filename manipulation commands in unix.

554

---

---

Differentiate cat command from more command.

578

---

Explain command to view process running?

617

---

What is awk used for?

622

---

What is the use of finger command?

599

---

What is the pipe command?

578

---

How do I use nslookup?

575

---

Can you explain a little bit about command substitution?

611

---

How does the system know where one command ends and another begins?

1578

---

Why is grep called grep?

782

---

What is merge command in unix?

946

---