The document discusses various features and commands related to Linux operating systems. It describes features like being free and open-source, graphical user interfaces, and portability. It also provides examples and explanations of basic Linux commands like echo, head, tail, sort, uniq, and others. Fun commands like sl, fortune, cowsay and cmatrix are also mentioned.

1. Dr. D. P.
Mishra
Digitally signed by Dr. D. P.
Mishra
DN: cn=Dr. D. P. Mishra, o=durg,
ou=BIT,
email=dpmishra@bitdurg.ac.in,
c=IN
Date: 2023.02.14 12:44:22
+05'30'

2. Features of Linux Environment

3. Features of Linux Operating Systems?
• Free and Open-Source. ...
• Extremely Flexible. ...
• Lightweight Infrastructure. ...
• Graphical User Interface (GUI) ...
• End-to-end encryption. ...
• Portable Environment. ...
• Shell/ Command-line Interface. ...
• Customized keyboard.
• Multiuser, multitasking, portability, security …
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4. Is shell A Programming Language?
• A Unix shell is both a command interpreter and a programming
language.
• As a command interpreter, the shell provides the user interface to the
rich set of GNU utilities
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5. Basic Commands.
• $ echo command :
• Echo is a Unix/Linux command tool used for displaying lines of text or string
which are passed as arguments on the command line.
• This is one of the basic command in Linux and most commonly used in shell
scripts.
• $ echo [option] [string]
• $ echo Hello, World!
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6. Basic Commands..
• who
• date
• pwd
• cd
• mkdir
• rmdir
• ls
• cp
• mv
• rm
• cat
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7. Date , Time & Calendar
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8. Basic Commands…
• more command is used to view the text files in the command prompt,
displaying one screen at a time in case the file is large (For example log
files).
• The more command also allows the user do scroll up and down
through the page.
• $ more -d sample.txt
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$ more -f sample.txt
-p : This option clears the screen and then displays the text.
-c : This command is used to display the pages on the same area by overlapping the previously
displayed text.
more -c sample.txt

10. wc command
• wc command gives us useful information about a file by returning no.
of lines, words and bytes
• The first column returned is the number of lines.
• The second is the number of words.
• The third is the number of bytes.
• $ echo test >> test.txt
• $ wc test.txt
1 1 5 test.txt
• Example via pipes, we can count the output of running the ls –al
command:
• $ ls –al |wc
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11. find command
• The $ find command can be used to find files or folders matching a
particular search pattern.
• It searches recursively
• Example : Find all the files under the current tree that have the .txt
extension and print the relative path of each file matching:
$ find -name '*.txt‘
• It's important to use quotes around special characters like * to avoid
the shell interpreting them.
• Find directories under the current tree matching the name "src"
$ find . -type d -name src
• You can search under multiple root trees:
$ find folder1 folder2 -name filename.txt
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12. $ head command
• The head command writes to standard output a specified number of
lines or bytes of each of the specified files, or of the standard input.
• If no flag is specified with the head command, the first 10 lines are
displayed by default
• The File parameter specifies the names of the input files.
• Example :
$ nano example1.txt
• Add following lines in file
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13. example1.txt :
Connecticut
Delaware
Georgia
Maryland
Massachusetts
New Hampshire
New Jersey
New York
North Carolina
Pennsylvania
Rhode Island
South Carolina
Virginia
Save and exit the file (press Ctrl+X and then Y to confirm)
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14. $ cat example1.txt
$ head example1.txt
• For displaying number of lines –
$ head -n 4 example1.txt
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15. • For displaying no. of bytes : use the -c (--bytes) argument
• To see 20 bytes of output of the sample file, you would run
$ head -c 20 example1.txt
• For displaying filename tag : To display the file name before
outputting the first 10 lines, add the -v (--verbose) option:
$ head -v example1.txt
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16. Displaying Multiple Files with head
• You can also display the first lines of multiple files using a single
command:
$ head [option] file_name1 file_name2
$ head example1.txt example2.txt
$ head -n 4 example1.txt example2.txt
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17. Redirecting output to a text file
• You can redirect the output from the head command to a text file (or
log file) using the greater-than sign (>).
• Instead of displaying the lines in standard output, they are placed into
the wanted file.
• Syntax for redirecting output from head command is :
$ head [options] file_name > output_file
• To redirect the first 10 lines of example1.txt to a file
named output1.txt, you would run the command:
$ head example1.txt > output1.txt
$ cat output1.txt
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18. Using head with Pipeline
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• head can be piped to one or more commands to modify the output:
• Syntax:
[command] | head [option]
• For example, to list files in the /etc directory using the ls command and
print 10 entries, you would run the command:
$ ls /etc | head

19. $ tail
• tail command prints the last few number of lines (10 lines by default)
of a certain file, then terminates.
• By default “tail” prints the last 10 lines of a file, then exits.
• This is great for watching log files, for example:
tail -f /var/log/system.log
$ ctrl-C
$ tail -n 10 <filename>
• You can print the whole file content starting from a specific line using +
before the line number:
tail -n +10 <filename>
• $ tail can do much more and as always my advice is to check man tail
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20. $ sort command
• SORT command is used to sort a file, arranging the records in a
particular order.
• By default, the sort command sorts file assuming the contents are
ASCII.
• Using options in the sort command can also be used to sort
numerically.
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21. • $ cat > file.txt
abhishek
chitransh
satish
rajan
naveen
divyam
harsh
• $ sort file.txt
• Output :
abhishek
chitransh
divyam
harsh
naveen
rajan
Satish
Note: This command does not
actually change the input file
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Create a data file

22. $ nl command
• The nl command reads the
File parameter (standard
input by default), numbers
the lines in the input, and
writes the numbered lines to
standard output.
• nl command is a Unix/Linux
utility that is used for
numbering lines, accepting
input either from a file or
from STDIN.
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23. • $ cat list.txt
apples
oranges
potatoes
lemons
garlic
• $ nl list.txt
1 apples
2 oranges
3 potatoes
4 lemons
5 garlic
• $ nl list.txt > nlist.txt
• $ cat nlist.txt
1 apples
2 oranges
3 potatoes
4 lemons
5 garlic
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Example of nl command
In the example above, we run the same nl command, but
redirect the output to a new file, nlist.txt. Then we use cat to
display the results.

24. $ uniq command
• Linux uniq command is used to remove all the repeated lines from a
file.
• Also, it can be used to display a count of any word, only repeated lines,
ignore characters, and compare specific fields
• Syntax :
$ uniq [OPTION]... [INPUT [OUTPUT]]
• Some useful command line options of the uniq command are as following:
• -c, --count: it prefixes the lines by the number of occurrences.
• -d, --repeated: it is used to print duplicate lines, one for each group.
• -D: It is used to print all the duplicate lines.
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25. • Remove repeated lines
$ sort filename.txt | uniq
• Counting occurences of word
• $ sort filename.txt | uniq –c
• Displaying repeated lines -d
• $ sort filename.txt | uniq –d
• Display unique lines - u option
$ sort filename.txt | uniq –u
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Examples of uniq command

26. Linux Funny Commands
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27. 1. Command: sl (Steam Locomotive)
• $ sl
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28. 2. telnet towel.blinkenlights.nl
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telnet towel.blinkenlights.nl

29. 3. Fortune
• $ fortune - gives random funny fortune
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30. 4. Factor
• $ factor 1111
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31. 5. cowsay
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32. 6. banner
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33. 7. figlet
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34. 8. cmatrix
• You might have seen the Hollywood movie ‘matrix‘ & fascinated with.
• For displaying an animation that looks like Hacker‘s desktop.
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