What is UNIX?
It is a portable operating system that is designed for both efficient multi-tasking and multi-user functions. Its portability allows it to run on different hardware platforms. It was written is C and lets users do processing and control under a shell.
2) What are filters?
The term filter is often used to refer to any program that can take input from standard input, perform some operation on that input, and write the results to standard output. A Filter is also any program that can be used between two other programs in a pipeline.
3) What is a typical syntax being followed when issuing commands in shell?
Typical command syntax under the UNIX shell follows the format:
Command [-argument] [-argument] [--argument] [file]
4) Is there a way to erase all files in the current directory, including all its sub-directories, using only one command?
Yes, that is possible. Use "rm –r *" for this purpose. The rm command is for deleting files. The –r option will erase directories and subdirectories, including files within. The asterisk represents all entries.