What is the significance of the tee command?
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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.
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Explain the following commands.
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$ ls > file1
$ banner hi-fi > message
$ cat par.3 par.4 par.5 >> report
$ cat file1>file1
$ date ; who
$ date ; who > logfile
$ (date ; who) > logfile
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Construct pipes to execute the following jobs.
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1. Output of who should be displayed on the screen with
value of total number of users who have logged in
displayed at the bottom of the list.
2. Output of ls should be displayed on the screen and
from this output the lines containing the word ‘poem’
should be counted and the count should be stored in a
file.
3. Contents of file1 and file2 should be displayed on
the screen and this output should be appended in a file
.
From output of ls the lines containing ‘poem’ should be
displayed on the screen along with the count.
4. Name of cities should be accepted from the keyboard .
This list should be combined with the list present in a
file. This combined list should be sorted and the sorted
list
should be stored in a file ‘newcity’.
5. All files present in a directory dir1 should be
deleted any error while deleting should be stored in a
file ‘errorlog’.
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Which are typical system directories below the root directory?
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(1)/bin: contains many programs which will be executed
by users (2)/etc : files used by administrator (3)/dev:
hardware devices (4)/lib: system libraries (5)/usr:
application software (6)/home: home directories for
different systems.
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What is ex and vi ?
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ex is Unix line editor and vi is the standard Unix
screen editor.
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Explain kernal and shell.
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Kernal: It carries out basic operating system functions
such as allocating memory, accessing files and handling
communications. Shell:A shell provides the user
interface to the kernal.There are 3 major shells :
C-shell, Bourne shell , Korn shell
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Explain different types of Unix systems.
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The most widely used are: 1. System V (AT&T) 2. AIX
(IBM) 3. BSD (Berkeley) 4. Solaris (Sun) 5. Xenix ( A PC
version of Unix)
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In what way the protection fault handler concludes?
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After finishing the execution of the fault handler, it
sets the modify and protection bits and clears the copy
on write bit. It recalculates the process-priority and
checks for signals.
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For which kind of fault the page is checked first?
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The page is first checked for the validity fault, as
soon as it is found that the page is invalid (valid bit
is clear), the validity fault handler returns
immediately, and the process incur the validity page
fault. Kernel handles the validity fault and the process
will incur the protection fault if any one is present.
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What do you mean by the protection fault?
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Protection fault refers to the process accessing the
pages, which do not have the access permission. A
process also incur the protection fault when it attempts
to write a page whose copy on write bit was set during
the fork() system call.
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