Question 1
The Linux command “mknod myfifo b 4 16”
Will create a character device if the user is root
Will create a named pipe FIFO if the user is root
Will create a block device if the user is root
None of the above
       Operating-Systems       Linux-Operating-systems       ISRO-2017 May
Question 1 Explanation: 
The mknod command makes a directory entry and corresponding inode for a special file. The first parameter is the name of the Name entry device. Select a name that is descriptive of the device. The mknod command has two forms that have different flags.
Syntax: mknod Name { b | c } Major Minor
Question 2

Which UNIX/Linux command is used to make all files and sub-directories in the directory “progs” executable by all users ?

chmod−R a+x progs
chmod−R 222 progs
chmod−X a+x progs
chmod−X 222 progs
       Operating-Systems       Linux-Operating-systems       UGC-NET JUNE Paper-2
Question 2 Explanation: 
Here, observe 2 key points is
1. All files and their subdirectories
2. Execute by all users
Step-1: Normally any file consists of 3 categories.
1. Owner
2. Group
3. Others
Step-2: Every category is represented in 3 accesses.
1. Read(Octal value 4)
2. Write(Octal value 2)
3. Execute(Octal value 1)
Step-3: To change user permission, we are using command is chmod.
Chmod syntax: chmod permissions filename
1. All files and their subdirectories (using recursive command ‘R’)
2. Execute by all users(using ‘a+x’ subcommand. ‘a’ is nothing but all and ‘+x’ is execute permissions)
Actual command required: chmod− R a+x progs
Question 3
Linux operating system uses
Affinity Scheduling
Fair Preemptive Scheduling
Hand Shaking
Highest Penalty Ratio Next
       Operating-Systems       LINUX-Operating-systems       UGC NET CS 2013 Dec-paper-2
Question 3 Explanation: 
Linux operating system uses fair Preemptive Scheduling.
Ex: Round Robin
There are 3 questions to complete.
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