Question

Part 3. Self Test 3 from the textbook 1) When you enter following command, what happens and why? S catdog 2) What results from the following commands? A) S who | grep SUSER B) 5 grep \SHOME filel C) $ echo >> filel D) S echo '* >> filel E) S ps F) S. files G) S set noclobber H) S set -o 1) $ chmod +x file2 3) How can we change the prompt to be Next? in both families of shells (C shells and Korn shells)? 4) What data is passed in each field in the passwd file? 5) What command instructs the shell not to accept CTRL-D as a signal to log off?

Answer 1

1) cat > dog
When you enter this command it will create a file with name dog in current working directory. Also it allow us to write to the file.

2)
A)who | grep $USER
===================
who => displays who is logged in
grep => is pattern searcher
The computer outputs who you are, when you logged on and where you logged on from.

B)grep \$HOME file1
===================
 If there is no "file1" on your computer it tells you that grep: file1: no such file or directory.


C) echo u*>>file1
=================
This will create a file named file1 in current directory and write uan to it. If file exists then it will append uan to it.

D) echo 'u*'>>file1
==================
This will create a file named file1 in current directory and write u* to it. If file exists then it will append u* to it.

E) ps
=====
it will display current running process status in our system

F) . fileA
==========
Computer will try to execute the .fileA

G) set noclobber
===============
If you are in the csh or tcsh shells it tells the computer to not allow files to be overwritten, but if you are in ksh or bash shells it does nothing. The correct command for ksh or bash shells would be set -o noclobber.

H) Set -o
-=========
This tells you which functions are on or off.

I)chmod +x file2
================
It will make file2 as executable.


3.) How can we change the prompt to be Next? in both families of shells(C shells and Korn shells)?
In C shells(csh and tcsh) type in set prompt='Next?'. In Korn shells(sh, bash, and ksh) type PS1='Next?'.

4) What data is passed in each filed in passwd file?
Username:password:UserID:Group ID (GID):User ID Info:Home directory:Command/shell

5)What command instructs the shell not to accept CTRL-D as a signal to log off?
In the csh or tcsh shells use set ignoreeof, and in the ksh or bash shells use set-o ignoree of.