What is a Make file?
Make file is a utility in Unix to help compile large programs. It helps by only compiling the portion of the program that has been changed
Could you tell something about the Unix System Kernel?
The kernel is the heart of the UNIX operating system, it’s responsible for controlling the computer’s resources and scheduling user jobs so that each one gets its fair share of resources.
How can you tell what shell you are running on UNIX system?
You can do the Echo $RANDOM. It will return a undefined variable if you are from the C-Shell, just a return prompt if you are from the Bourne shell, and a 5 digit random numbers if you are from the Korn shell. You could also do a ps -l and look for the shell with […]
What do you mean by u-area (user area) or u-block?
This contains the private data that is manipulated only by the Kernel. This is local to the Process, i.e. each process is allocated a u-area.
What scheme does the Kernel in Unix System V follow while choosing a swap device among the multiple swap devices?
Kernel follows Round Robin scheme choosing a swap device among the multiple swap devices in Unix System V.
List the system calls used for process management:
System calls Description
fork() To create a new process
exec() To execute a new program in a process
wait() […]
How do you change File Access Permissions?
Every file has following attributes:
owner’s user ID ( 16 bit integer )
owner’s group ID ( 16 bit integer )
File access mode word
‘r w x -r w x- r w x’
(user permission-group permission-others permission)
r-read, w-write, x-execute
To change the access mode, we use chmod(filename,mode).
Example:
To change mode of myfile to ‘rw-rw-r–’ (ie. read, write permission for user – […]
Explain the layered aspect of a UNIX system. What are the layers? What does it mean to say they are layers?
A UNIX system has essentially three main layers:
. The hardware
. The operating system kernel
. The user-level programs
The kernel hides the system’s hardware underneath an abstract, high-level programming interface. It is responsible for implementing many of the facilities that users and user-level programs take for granted.
The kernel assembles all of the following UNIX concepts from lower-level […]
What is the use of ‘grep’ command?
‘grep’ is a pattern search command. It searches for the pattern, specified in the command line with appropriate option, in a file(s).
Syntax : grep Example : grep 99mx mcafile
What difference between cmp and diff commands?
cmp – Compares two files byte by byte and displays the first mismatch
diff – tells the changes to be made to make the files identical
What is the significance of the “tee” command?
It reads the standard input and sends it to the standard output while redirecting a copy of what it has read to the file specified by the user.
Is ‘du’ a command? If so, what is its use?
Yes, it stands for ‘disk usage’. With the help of this command you can find the disk capacity and free space of the disk.
How to terminate a process which is running and the speciality on command kill 0?
With the help of kill command we can terminate the process.
Syntax: kill pid Kill 0 – kills all processes in your system except the login shell.