Types of Linux Shells

Types of Shells , viva voce Question

2. Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

3. Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

4. Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

5. Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

6. What is a Linux Shell and Why is it Important?
•Ashellis a command-line interpreter programthat parses and sends
commands to theoperating system.
•This program represents an operating system's interactive interface
and the kernel's outermost layer (or shell).
•It allows users and programs to send signals and expose an operating
system's low-level utilities.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

7. 1. Bourne Shell (sh)
•TheBourneshellwasthefirstdefaultshellonUnixsystems,released
in1979.
•Theshellprogramnameissh,andthetraditionallocationis/bin/sh.
•TheBourneshellquicklybecamepopularbecauseit
iscompactandfast.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

8. 2. C Shell (csh)
•TheC shell(csh) is a Linux shell from the late 1970s whose main
objective was to improve interactive use and mimic the C language.
•Since the Linux kernel is predominantly written in C, the shell aims to
provide stylistic consistency across the system.
Features:
•History of the previous command.
•User-defined aliases for programs.
•Relative home directory (~).
•Built-in expression grammar.
Drawbacks of the C shell are:
•Syntax inconsistencies.
•No support for standard input/output (stdio) file handles or functions.
•Not fully recursive, which limits complex command handling.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

9. 3. TENEX C Shell (tcsh)
•The TENEX C shell (tcsh) is an extension of the C shell (csh) merged in
the early 1980s.
•The shell is backward compatible with csh, with additional features
and concepts borrowed from the TENEX OS.
Features of the shell include:
•Advanced command history.
•Programmable autocomplete.
•Wildcard matching.
•Job control.
•Built-in where command.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

10. 4. KornShell(ksh)
•The KornShell(ksh) is a Unix shell and language based on the Bourne
shell (sh) developed in the early 1980s.
•The location is in /bin/kshor /bin/ksh93,
•while the prompt is the same as the Bourne shell ($ for a user and #
for root).
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

11. 5. DebianAlmquistShell (dash)
•The DebianAlmquistShell (dash) is a Unix shell developed in the late
1990s from the Almquistshell (ash), which was ported to Debianand
renamed.
•Dash is famous for being the default shell for Ubuntu and Debian.
•The shell is minimal and POSIX compliant, making it convenient for OS
startup scripts.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

12. 6. Bourne Again Shell (bash)
•The Bourne Again shell is a Unix shell and command language created
as an extension of the Bourne shell (sh) in 1989.
•The shell program is the default login shell for many Linux distributions
and earlier versions of macOS.
•The shell name shortens to bash, and the location is /bin/bash.
•Like the Bourne shell, the bash prompt is $ for a regular user and # for
root.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

13. 7. Z Shell (zsh)
•The Z shell (zsh) is a Unix shell created as an extension for the Bourne
shell in the early 1990s.
•The feature-rich shell borrows ideas from kshand tcshto create a well-
built and usable alternative.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

14. 8. Friendly Interactive Shell (fish)
•The Friendly Interactive Shell (fish) is a Unix shell released in the mid-
2000s with a focus on usability.
•The feature-rich shell does not require additional configuration, which
makes it user-friendly from the start.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

15. Viva Questions
1.what is an file system?
2.why we are using sedcommand?
3.which command is used to create file?
4.why we are using chmod?
5.which permissions are provided to files?
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

16. Viva Questions
1.what is an directory?
2.which command is used to create directory?
3.what is the purpose of wccmd?
4.which command is used to change the directory
5.why we are using grepcommand?
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

17. Viva Questions
1.what is an shell script?
2.why we are using egrepcommand?
3.what is the purpose of fgrep?
4.write a syntax of grep?
5.what is an shell variable?
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

18. Viva Questions
1.which command is used to display a file?
2.why we are using fd?
3.why we are using popenfunction?
4.why we are using mv command?
5.how we can assign permissions to the files?
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg

19. #!/bin/bash
read -p "Enter a string: " str
# reverse the string
reverse=$(echo $str| rev)
if [ "$str" == "$reverse" ]; then
echo "The string is a palindrome."
else
echo "The string is not a
palindrome."
fi
•The rev command is used to
reverse the string.
•The if statement checks if the
original string is equal to the
reversed string.
•If they are equal, it means the
string is a palindrome and the
script prints a message
accordingly.
•e.g. RACECAR , LEVEL
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg
9.1 Shell script to check palindrome or not

20. #!/bin/bash
read -p "Enter the first string: " str1
read -p "Enter the second string: " str2
if [ "$str1" == "$str2" ];
then
echo "The strings are equal."
else
echo "The strings are not equal."
fi
•Theifstatementchecksifthetwo
stringsareequal.
•Iftheyareequal,itmeansthat
thestringsarethesameandthe
scriptprintsamessagesayingthat
theyareequal.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg
9.2 Shell Script to compare two Strings

21. #!/bin/bash
if [ $# -eq0 ]; then
echo "Error: No file name specified."
exit 1
fi
filename=$1
if [ -r $filename ] && [ -w $filename ]; then
echo "The file $filename has both read and write permission."
elif[ -r $filename ]; then
echo "The file $filename has read permission but not write permission."
elif[ -w $filename ]; then
echo "The file $filename has write permission but not read permission."
else
echo "The file $filename does not have read or write permission."
fi
•Theifstatementchecksifthefile
hasbothreadandwrite
permissionusingthe-rand-w
optionsrespectively.
•Ifithasbothpermissions,the
scriptprintsamessagesayingthat
thefilehasbothreadandwrite
permission.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg
9.3 Write a script to read file name from command line
and check if it read and write permission or not

22. #!/bin/bash
count=0
for file in *
do
if [ -f $file ]; then
((count++))
fi
done
echo "The number of files in the current directory
is: $count"
•Theifstatementchecksifthe
currentfileisaregularfileusing
the-foption.
•Ifitis,thescriptincrementsthe
countvariable.
•Aftertheloopcompletes,the
scriptprintsthenumberoffilesin
thecurrentdirectory.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg
9.4 Write a shell script to count number of only files
present in current directory.

23. #!/bin/bash
read -p "Enter a string: " str
reverse=""
for (( i=${#str}-1; i>=0; i--))
do
reverse="$reverse${str:$i:1}"
done
echo "The reversed string is: $reverse"
•Thescriptinitializesanemptystring
calledreverse.
•Theforloopiteratesthrougheach
characterinthestringstrinreverse
order.
•Itusesparameterexpansionto
extractthecharacterateachindex
andappendsittothereversestring.
•Aftertheloopcompletes,thescript
printsthereversedstring.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg
9.5 Write a script to reverse a given string.

24. Task / Assignment
1.Write a script to copy list of file into specified directory.
2.Write a shell script to list all of the directory files in a directory.
3.Write a shell script to count number of words present in a file
without using commands.
Linux Laboratory
-
B.Tech. 6th CSE
-
Dr. D. P. Mishra, BIT Durg