Unix And Shell Programming

Explain shell features of while and for with syntax.

i) Differentiate between hard link and symbolic link

ii) Explain significance of permissions to directory.

What does touch foo command mean? Why touch command is important for the system administrator?

Explain with example:

i) head 

Explain with example:

ii) tail

Explain with example:

iii) cut

With the help of example explain grep command and list its options with their significance.

Explain line addressing and context addressing in sed with example.

Briefly explain interval regular expression and tagged regular expression.

Explain with examples:

iv) MAIL

What is exit status of a command and where it is stored? And how it can be accessed? Give examples. 

Write a shell code to accept a string from the terminal and display suitable message if it doesn't have at least 10 characters using : i) case ii) expr. 

What is AWK? Explain any three built in functions of AWK.

What are associative arrays? How they are implemented in AWK?

With syntax and examples, explain control flow statements in AWK. 

Explain any three string handling functions in Perl.

With suitable examples explain split and join functions in Perl.

Write a Perl program that prompts the user to input string and a number and prints the string those many times on different lines to standard output.

Write UNIX commands

iii) To copy all files stored in /home/vtu with  and extensions to progs directory in current directory

With the help of examples, explain the command:

i) apropos

With the help of examples, explain the command:

ii) what is

Explain with suitable example:

i) absolute and relative pathnames 

Explain with suitable example:

ii) internal and external commands.

Files current permissions are rw --W-r- writo chmod expressions required to change to change. them for the following AND FOR CONES

i) r--r ----X

in) rwxrwx--X

iii) r-xr-xr-x

iv) rwxrwxr--

using both relative and absolute methods of assigning permissions

What are different modes of vi editor? Explain with a neat diagram.

Write UNIX commands

i) Find and replace all the occurrences of unix with UNIX in the text file after confirming the user (vi editor command).

Write UNIX commands

ii) List all the files in PWD which are having exactly five characters in their filename and any number of characters in their extension

With neat diagram, explain architecture of UNIX operating system.

Write UNIX commands

iv) To delete all files containing  in their file name 

Write UNIX commands

v) To delete all files with three character extension except out from current directory

Write UNIX commands

vi) To display (list) contents of current directory and its subdirectories

Explain 3 standard files supported by UNIX. Also give details about special files used for output redirection in UNIX. 

Explain mechanism of process creation. Also given details about process states and zombies. 

Explain with examples:

i) cron 

Explain with examples:

ii) HOME

Explain with examples:

iii) PATH