Ans.
Unix assign a unique number to every process running in the memory. This
number is called process ID or simply PID. The PIDs start with 0 and run unto a
maximum of 32767.
To kill a process we must first note the PID of the process to be killed using the
ps command. e.g.
$ cat employee.dat | grep ‘Nagpur’ | sort > output.dat &
6173
$
If the above background process is to be killed we must execute the following
command
$ kill 6173
6173 Terminated.

Ans:
$ cat file1 file2 > file3

Ans:
cmp :- Compares two files, and if they differ, tells the first byte and line number
where they differ.
We can use the `cmp' command to show the offsets and line numbers where two
files differ. `cmp' can also show all the characters that differ between the two
files, side by side.
SYNTAX
cmp options... FromFile [ToFile]
cmp file1 file2