FOSS

FREE OPEN SOURCE LAB

EXP-1:

Session-1

Log into the system
Use ‘VI” editor to create a file called myfile.txt which contains some text.
Correct typing errors during creation
Save the file
Logout of the system

Log into the system

When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as

password:

Then we get log into the commands.

Use vi editor to create a file called myfile.txt which contains some text

Syntax:-vi file name

Description:

Ø Vi Command is used to create and editing a file;

Ø If we type "vi filename".

ü If the file named filename exists, then the first page (or screen) of the file will be displayed;

ü If the file does not exist, then an empty file and screen are created into which you may enter text.

Example: vi myfile.text.

Correct typing errors during creation

In creating a file through vi editor an error an error will occur we modify the file by opening the file again. An error will occur when we don’t give space between filename and command name

Example: vikrishnasai

Save the File.

To save the file created in vi editor we press esc “:WQ” .It means that saves the file and Quits editing mode .then we come out from the vi editor.

:wq:- quit vi, writing out modified file to file named in original invocation

:q!:- quit vi even though latest changes have not been saved for this vi call

:x:- quit vi, writing out modified file to file named in original invocation

Logout the system.

Syntax: exit

Description: In our current directory press exit to log out from the commands

Session-2

Log into the system
Open the file created in session-1.
Add some text
Change some text
Delete some text.
Save the file
Logout of the system

a. Log into the system

When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as

password:

Then we get log into the commands.

b. Open the file created in session -1

Syntax: vi filename

In the above session we create a file in vi editor To open the file created in Session 1 we have to type as follows “vi filename”

c. Add Some text:

To add some text to the file which is already created first we have to open that file then add text.

vi filename. Text

The following commands allow you to insert and add text. Each of these commands puts the vi editor into insert mode; thus, the <Esc> key must be pressed to terminate the entry of text and to put the vi editor back into command mode.

Ø i:- insert text before cursor, until <Esc> hit

Ø I:- insert text at beginning of current line, until <Esc> hit

Ø a:- append text after cursor, until <Esc> hit

Ø A:- append text to end of current line, until <Esc> hit

Ø o:- open and put text in a new line below current line, until <Esc> hit

Ø O:- open and put text in a new line above current line, until <Esc> hit

d. Changing Text

To change the some text in myfile. text move the cursor where we want to change the text After that replace the text under cursor with other text first open the file as follows.

vi myfile.text

The following commands allow you to modify text.

Ø r:- replace single character under cursor (no <Esc> needed)

Ø R:- replace characters, starting with current cursor position, until <Esc> hit

Ø cw:- change the current word with new text, starting with the character under cursor, until <Esc> hit

Ø cNw:-change N words beginning with character under cursor, until <Esc> hit;

Ø e.g., c5w changes 5 words

Ø C:- change (replace) the characters in the current line, until <Esc> hit

Ø cc:- change (replace) the entire current line, stopping when <Esc> is hit

Ø Ncc or cNc:-change (replace) the next N lines, starting with the current line, stopping when <Esc> is hit

e. Delete some text

To delete text in my file text we first move the cursor to end of that line and then press delete then the line is erased to do this first we open the file as

vi myfile.text

The following commands allow you to delete text.

Ø x:- delete single character under cursor

Ø Nx:- delete N characters, starting with character under cursor

Ø dw:- delete the single word beginning with character under cursor

Ø dNw:-delete N words beginning with character under cursor;

Ø e.g., d5w deletes 5 words

Ø D:- delete the remainder of the line, starting with current cursor position

Ø dd:- delete entire current line

Ø Ndd or dNd:-delete N lines, beginning with the current line; e.g., 5dd deletes 5 lines

f. Save the changes:

To save the changes made in file myfile.text we press

esc:WQ

It means that saves the file and quits editing mode then we log out from the vi Mode.

Logout the system.

Syntax: exit

Description: In our current directory press exit to log out from the commands

*********************************************************************************

EXP-2:

Log into the system
Use the ‘cat’ command to create a file containing the following data. Call it mytable use tabs to separate the fields.

1425 ravi 15.65

4320 ramu 26.27

6830 sita 36.15

1450 raju 21.86

Use the cat command to display the file, mytable.
Use the ‘vi’ command to correct any errors in the file, mytable.
Use the ‘sort’ command to sort the file my table according to the first field. Call the sorted file my table (same name)
Print the file mytable.
Use the cut and paste commands to swap fields 2 and 3 of mytable. Call it my table (Same name)
Print the new, my table.
Logout of the system

Log into the system

When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as

password:

Then we get log into the commands.

Use the cat command to create a file containing the following data. Call it mytable use tabs to separate the fields.

1425 Ravi 15.65

4320 Ramu 26.27

6830 Sita 36.15

1450 Raju 21.86

cat > mytable

1425 Ravi 15.65

4320 Ramu 26.27

6830 Sita 36.15

1450 Raju 21.86

To save the file press Ctrl + D or Ctrl+Z

Description:-

Cat Command can view the file data and create a new file and also concatenate file

ü Creating file

Cat>file1.txt

ü Creating one file from several files

cat file1 file2 file3 > file4

This command combines the contents of the first three files into file4. With this command, file4 is created if it didn't already exist. (Or, it will overwrite file4 if file4 already existed.)

ü Showing line numbers

cat -n myfile.txt

cat myfile -b

This prints the line number before each line that is output

ü appending one file to another file

cat file1>>file2

Append file1 at the end of the file2

Use the cat command to display the file, mytable.

$cat mytable

1425 Ravi 15.65

4320 Ramu 26.27

6830 Sita 36.15

1450 Raju 21.86

Use the vi command to correct any errors in the file ,mytable

By using vi editor we have to correct errors occurred in creating file .

Open the file in vi editor as

Syntax: Vi mytable

Use vi command to correct errors

Use the sort command to sort the file mytable according to the first field. Call the sorted file my table

$sort +1 mytable > mytable

$ sort -k 1 mytable > sortfile;cp sortfile mytable

Description:-

Sort:- is a simple and very useful command which will rearrange the lines in a text file so that they are sorted, numerically and alphabetically.

Syntax: sort [OPTION]... [FILE]...

Options

Ø -b, --ignore-leading-blanks Ignore leading blanks.

Ø -d, --dictionary-order Consider only blanks and alphanumeric characters.

Ø-f, --ignore-case Fold lower case to upper case characters.

Ø -g, --general-numeric-sort Compare according to general numerical value.

Ø -i, --ignore-nonprinting Consider only printable characters.

Ø -M, --month-sort Compare (unknown) < `JAN' < ... < `DEC'.

Ø -h, --human-numeric-sort Compare human readable numbers (e.g., "2K", "1G").

Ø -n, --numeric-sort Compare according to string numerical value.

Ø -R, --random-sort Sort by random hash of keys.

Ø --random-source=FILE Get random bytes from FILE.

Ø -r, --reverse Reverse the result of comparisons.

Ø --sort=WORD Sort according to WORD: general-numeric -g, human-numeric -h, month -M, numeric -n, random -R, version -V.

Ø -V, --version-sort Natural sort of (version) numbers within text.

Note that this command does not actually change the input file, data.txt. If you want to write the output to a new file, output.txt, redirect the output like this:

sort data.txt > output.txt

You can perform a reverse-order sort using the -r flag. For example, the following command:

sort -r data.txt

Print the file mytable

cat mytable

1425 Ravi 15.65

1450 Raju 21.86

4320 Ramu 26.27

6830 Sita 36.15

Use the cut and paste commands to swap fields 2 and 3 of mytable. Call it my table (same name)

$cut -f1 > mytab1

$ cut –f 2 > mytab 2

$cut –f 3 > my tab3

$paste mytab3 mytab2 > mytab4

$paste mytab1 mytab4 > mytable

Description:

Cut

Remove or "cut out" sections of each line of a file or files.

Syntax

cut OPTION... [FILE]...

Options

Ø -b, --bytes=LIST Select only the bytes from each line as specified in LIST. LIST specifies a byte, a set of bytes, or a range of bytes; see Specifying LIST below.

Ø -c, --characters=LIST Select only the characters from each line as specified in LIST. LIST specifies a character, a set of characters, or a range of characters; see Specifying LISTbelow.

Ø -d, --delimiter=DELIM use character DELIM instead of a tab for the field delimiter.

Ø -f, --fields=LIST select only these fields on each line; also print any line that contains no delimiter character, unless the -s option is specified. LIST specifies a field, a set of fields, or a range of fields; see Specifying LIST below.

Ø -n This option is ignored, but is included for compatibility reasons.

Ø --complement complement the set of selected bytes, characters or fields.

Ø -s, --only-delimited do not print lines not containing delimiters.

Ø --output-delimiter=STRING use STRING as the output delimiter string. The default is to use the input delimiter.

To "cut" only the third field of each line, use the command:

cut -f 3 data.txt

If instead you want to "cut" only the second-through-fourth field of each line, use the command:

cut -f 2-4 data.txt

If you want to "cut" only the first-through-second and fourth-through-fifth field of each line (omitting the third field), use the command:

cut -f 1-2,4-5 data.txt

If you want the third field and every field after it, omitting the first two fields. In this case, you could use the command:

cut -f 3- data.txt

Specifying a range with LIST also applies to cutting characters (-c) or bytes (-b) from a line. For example, to output only the third-through-twelfth character of every line ofdata.txt, use the command:

cut -c 3-12 data.txt

paste command:

The paste command displays the corresponding lines of multiple files side-by-side.

Syntax: paste [OPTION]... [FILE]...

Examples: paste file1.txt file2.txt

This command would display the contents of file1.txt and file2.txt, side-by-side, with the corresponding lines of each file separated by a tab.

$ cat file1

Linux

Unix

Solaris

HPUX

AIX

paste command with a single file:

1. paste command without any options is as good as the cat command when operated on a single file.

$ paste file1

Linux

Unix

Solaris

HPUX

AIX

2. Join all lines in a file:

$ paste -s file1

Linux Unix Solaris HPUX AIX

-s option of paste joins all the lines in a file. Since no delimiter is specified, default delimiter tab is used to separate the columns.

3. Join all lines using the comma delimiter:

$ paste -d, -s file1

Linux,Unix,Solaris,HPUX,AIX

-d option is used to specify the delimiter. Using this -d and -s combination, all the lines in the file get merged into a single line.

4. Merge a file by pasting the data into 2 columns:

$ paste - - < file1

Linux Unix

Solaris HPUX

AIX

The '-' reads a line from the standard input. Two '-' reads 2 lines and pastes them side by side.

5.Merge a file by pasting the data into 2 columns using a colon separator:

$ paste -d':' - - < file1

Linux:Unix

Solaris:HPUX

AIX:

This is same as joining every 2 lines in a file.

6. Merge a file by pasting the file contents into 3 columns:

$ paste - - - < file1

Linux Unix Solaris

HPUX AIX

7. Merge a file into 3 columns using 2 different delimiters:

$ paste -d ':,' - - - < file1

Linux:Unix,Solaris

HPUX:AIX,

The -d option can take multiple de-limiters. The 1st and 2nd columns is separated by ':', whereas the 2nd and 3rd are separated by a ','.

paste command examples for multiple files handling

Let us consider a file, file2, with the following contents:

$ cat file2

Suse

Fedora

CentOS

OEL

Ubuntu

8. paste contents of 2 files side by side.

$ paste file1 file2

Linux Suse

Unix Fedora

Solaris CentOS

HPUX OEL

AIX Ubuntu

paste command is used in scenarios to merge multiple files side by side. As shown above, the file contents are pasted side by side.

9. paste contents of 2 files side by side with a comma separator:

$ paste -d, file1 file2

Linux,Suse

Unix,Fedora

Solaris,CentOS

HPUX,OEL

AIX,Ubuntu

10. paste command can take standard input in case of multiple files too:

$ cat file2 | paste -d, file1 -

Linux,Suse

Unix,Fedora

Solaris,CentOS

HPUX,OEL

AIX,Ubuntu

Like this as well:

$ cat file1 | paste -d, - file2

Linux,Suse

Unix,Fedora

Solaris,CentOS

HPUX,OEL

AIX,Ubuntu

One more:

$ cat file1 file2 | paste -d, - -

Linux,Unix

Solaris,HPUX

AIX,Suse

Fedora,CentOS

OEL,Ubuntu

11. Read lines in both the files alternatively:

$ paste -d'\n' file1 file2

Linux

Suse

Unix

Fedora

Solaris

CentOS

HPUX

OEL

AIX

Ubuntu

Print the new file, mytable

cat mytable

1425 15.65 Ravi

1450 21.86 Raju

4320 26.27 Ramu

6830 36.15 Sita

Logout the system.

Syntax: exit

Description: In our current directory press exit to log out from the commands

*********************************************************************************

EXP-3:

a) Login to the system

b) Use the appropriate command to determine your login shell

c) Use the /etc/passwd file to verify the result of step b.

d) Use the ‘who’ command and redirect the result to a file called myfile1. Use the more command to see the contents of myfile1.

e) Use the date and who commands in sequence (in one line) such that the output of date will display on the screen and the output of who will be redirected to a file called myfile2. Use the more command to check the contents of myfile2.

a) Write a “sed” command that deletes the first character in each line in a file.

b) Write a “sed” command that deletes the character before the last character in each line in a file.

c) Write a “sed” command that swaps the first and second words in each line in a file.

Log into the system

When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as

password:

Then we get log into the commands.

use the appropriate command to determine your login shell

Syntax: $ echo $SHELL

Output: $ echo $SHELL

/bin/bash

Description:-

What is "the shell"?

Shell is a program that takes your commands from the keyboard and gives them to the operating system to perform. In the old days, it was the only user interface available on a Unix computer. Nowadays, we have graphical user interfaces (GUIs) in addition to command line interfaces (CLIs) such as the shell.

On most Linux systems a program called bash (which stands for Bourne Again SHell, an enhanced version of the original Bourne shell program, sh, written by Steve Bourne) acts as the shell program. There are several additional shell programs available on a typical Linux system. These include: ksh, tcsh and zsh.

Ø To find your current shell type following command

$ echo $SHELL

Ø Shell is a user program or it's environment provided for user interaction. Shell is an command language interpreter that executes commands read from the standard input device (keyboard) or from a file.

Ø Shell is not part of system kernel, but uses the system kernel to execute programs, create files etc.

Ø Several shell available with Linux including:

Shell Name	Developed by	Where	Remark
BASH ( Bourne-Again SHell )	Brian Fox and Chet Ramey	Free Software Foundation	Most common shell in Linux. It's Freeware shell.
CSH (C SHell)	Bill Joy	University of California (For BSD)	The C shell's syntax and usage are very similar to the C programming language.
KSH (Korn SHell)	David Korn	AT & T Bell Labs	--
TCSH	See the man page. Type $ man tcsh	--	TCSH is an enhanced but completely compatible version of the Berkeley UNIX C shell(CSH).

Ø To find all available shells in your system type following command:

$ cat /etc/shells

use the /etc/passwd file to verify the result of step b.

$cat /etc/passwd

Use the who command and redirect the result to a file called myfile1. Use the more command to see the contents of myfile1.

Sol : $who > myfile1 | more

User1 pts/0 Apr 23 10:43

User2 pts/1 May 6 18:19

Description:

Ø Who>myfile1àThe result of who command is stored in myfile1

Ø More myfile1àBy using more command we print the myfile1 contents

"who" command:

The Linux "who" command lets you display the users that are currently logged into your Unix computer system.

Syntax: who

On a very busy Unix/Linux system the output of the who command may scroll off your terminal screen. To solve that, pipe the output of the who command into the Linux more command, like this: who | more

The -a argument of the who command lists all available output for each user on your system.

who -a

more command:

is a command to view (but not modify) the contents of a text file one screen at a time.

The syntax for the more command is:

more [options] [files]

OPTIONS

Option Description

Ø -c Page through the file by clearing the window. (not scrolling).

Ø -d Displays "Press space to continue, 'q' to quit"

Ø -f Count logical lines rather than screen lines (wrapping text)

Ø -l Ignores form feed (^L) characters.

Ø -r Display all control characters.

Ø -s Displays multiple blank lines as one blank line.

Ø -u Does not display underline characters and backspace (^H).

Ø -w Waits for a user to press a key before exiting.

Ø -n Displays n lines per window.

Ø +num Displays the file starting at line number num.

Ø +/pattern Displays the file starting at two lines before the pattern.

Use the date and who commands in sequence (in one line) such that the output of date will display on the screen and the output of who will be redirected to a file called myfile2. Use the more command to check the contents of myfile2.

$ date;who > myfile2

Sat Aug 23 09:38:05 IST 2008

$ more myfile2

allam tty7 2008-08-23 09:08 (:0)

allam pts/1 2008-08-23 09:09 (:0.0)

A) Write a sed command that deletes the first character in each line in a file.

$ cat mytable

1425 Ravi 15.65

4320 Ramu 26.27

6830 Sita 36.15

1450 Raju 21.86

7820 Anil 23.34

9000 Allam 35.56

$ sed 's/^./ / ' mytable

425 Ravi 15.65

320 Ramu 26.27

830 Sita 36.15

450 Raju 21.86

820 Anil 23.34

000 Allam 35.56

B) Write a sed command that deletes the character before the last character in each line in a file.

# Delete the last character in each line in a file.

$ sed 's/.$/ /' mytable

1425 Ravi 15.6

4320 Ramu 26.2

6830 Sita 36.1

1450 Raju 21.8

7820 Anil 23.3

9000 Allam 35.5

C) Write a sed command that swaps the first and second words in a file.

# Swaps the first and second words in each line in a file.

$ sed ‘s/ $[^ ]*$ *$[^ ]*$/ \2 \1 /g’ mytable

Ravi 1425 15.65

Ramu 4320 26.27

Sita 6830 36.15

Raju 1450 21.86

Anil 7820 23.34

Allam 9000 35.56

descripiton

Sed is a Stream Editor used for modifying the files in unix (or linux). Whenever you want to make changes to the file automatically, sed comes in handy to do this.

>cat file.txt

unix is great os. unix is opensource. unix is free os.

learn operating system.

unixlinux which one you choose.

SED COMMAND EXAMPLES

1. Replacing or substituting string
Sed command is mostly used to replace the text in a file. The below simple sed command replaces the word "unix" with "linux" in the file.

>sed 's/unix/linux/' file.txt

linux is great os. unix is opensource. unix is free os.

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linuxlinux which one you choose.

Here the "s" specifies the substitution operation. The "/" are delimiters. The "unix" is the search pattern and the "linux" is the replacement string.

By default, the sed command replaces the first occurrence of the pattern in each line and it won't replace the second, third...occurrence in the line.

2. Replacing the nth occurrence of a pattern in a line.
Use the /1, /2 etc flags to replace the first, second occurrence of a pattern in a line. The below command replaces the second occurrence of the word "unix" with "linux" in a line.

>sed 's/unix/linux/2' file.txt

unix is great os. linux is opensource. unix is free os.

learn operating system.

unixlinux which one you choose.

3. Replacing all the occurrence of the pattern in a line.

The substitute flag /g (global replacement) specifies the sed command to replace all the occurrences of the string in the line.

>sed 's/unix/linux/g' file.txt

linux is great os. linux is opensource. linux is free os.

learn operating system.

linuxlinux which one you choose.

4. Replacing from nth occurrence to all occurrences in a line.
Use the combination of /1, /2 etc and /g to replace all the patterns from the nth occurrence of a pattern in a line. The following sed command replaces the third, fourth, fifth... "unix" word with "linux" word in a line.

>sed 's/unix/linux/3g' file.txt

unix is great os. unix is opensource. linux is free os.

learn operating system.

unixlinux which one you choose.

5. Changing the slash (/) delimiter
You can use any delimiter other than the slash. As an example if you want to change the web url to another url as

>sed 's/http:\/\//www/' file.txt

In this case the url consists the delimiter character which we used. In that case you have to escape the slash with backslash character, otherwise the substitution won't work.
Using too many backslashes makes the sed command look awkward. In this case we can change the delimiter to another character as shown in the below example.

>sed 's_http://_www_' file.txt

>sed 's|http://|www|' file.txt

6. Using & as the matched string

There might be cases where you want to search for the pattern and replace that pattern by adding some extra characters to it. In such cases & comes in handy. The & represents the matched string.

>sed 's/unix/{&}/' file.txt

{unix} is great os. unix is opensource. unix is free os.

learn operating system.

{unix}linux which one you choose.

>sed 's/unix/{&&}/' file.txt

{unixunix} is great os. unix is opensource. unix is free os.

learn operating system.

{unixunix}linux which one you choose.

7. Using \1,\2 and so on to \9
The first pair of parenthesis specified in the pattern represents the \1, the second represents the \2 and so on. The \1,\2 can be used in the replacement string to make changes to the source string. As an example, if you want to replace the word "unix" in a line with twice as the word like "unixunix" use the sed command as below.

>sed 's/\(unix\)/\1\1/' file.txt

unixunix is great os. unix is opensource. unix is free os.

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unixunixlinux which one you choose.

The parenthesis needs to be escaped with the backslash character. Another example is if you want to switch the words "unixlinux" as "linuxunix", the sed command is

>sed 's/\(unix\)\(linux\)/\2\1/' file.txt

unix is great os. unix is opensource. unix is free os.

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linuxunix which one you choose.

Another example is switching the first three characters in a line

>sed 's/^\(.\)\(.\)\(.\)/\3\2\1/' file.txt

inux is great os. unix is opensource. unix is free os.

aelrn operating system.

inuxlinux which one you choose.

8. Duplicating the replaced line with /p flag
The /p print flag prints the replaced line twice on the terminal. If a line does not have the search pattern and is not replaced, then the /p prints that line only once.

>sed 's/unix/linux/p' file.txt

linux is great os. unix is opensource. unix is free os.

linux is great os. unix is opensource. unix is free os.

learn operating system.

linuxlinux which one you choose.

linuxlinux which one you choose.

9. Printing only the replaced lines
Use the -n option along with the /p print flag to display only the replaced lines. Here the -n option suppresses the duplicate rows generated by the /p flag and prints the replaced lines only one time.

>sed -n 's/unix/linux/p' file.txt

linux is great os. unix is opensource. unix is free os.

linuxlinux which one you choose.

If you use -n alone without /p, then the sed does not print anything.

10. Running multiple sed commands.
You can run multiple sed commands by piping the output of one sed command as input to another sed command.

>sed 's/unix/linux/' file.txt| sed 's/os/system/'

linux is great system. unix is opensource. unix is free os.

learn operating system.

linuxlinux which one you chosysteme.

Sed provides -e option to run multiple sed commands in a single sed command. The above output can be achieved in a single sed command as shown below.

>sed -e 's/unix/linux/' -e 's/os/system/' file.txt

linux is great system. unix is opensource. unix is free os.

learn operating system.

linuxlinux which one you chosysteme.

11. Replacing string on a specific line number.
You can restrict the sed command to replace the string on a specific line number. An example is

>sed '3 s/unix/linux/' file.txt

unix is great os. unix is opensource. unix is free os.

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linuxlinux which one you choose.

The above sed command replaces the string only on the third line.

12. Replacing string on a range of lines.
You can specify a range of line numbers to the sed command for replacing a string.

>sed '1,3 s/unix/linux/' file.txt

linux is great os. unix is opensource. unix is free os.

learn operating system.

linuxlinux which one you choose.

Here the sed command replaces the lines with range from 1 to 3. Another example is

>sed '2,$ s/unix/linux/' file.txt

linux is great os. unix is opensource. unix is free os.

learn operating system.

linuxlinux which one you choose.

Here $ indicates the last line in the file. So the sed command replaces the text from second line to last line in the file.

13. Replace on a lines which matches a pattern.
You can specify a pattern to the sed command to match in a line. If the pattern match occurs, then only the sed command looks for the string to be replaced and if it finds, then the sed command replaces the string.

>sed '/linux/ s/unix/centos/' file.txt

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centoslinux which one you choose.

Here the sed command first looks for the lines which has the pattern "linux" and then replaces the word "unix" with "centos".

14. Deleting lines.
You can delete the lines a file by specifying the line number or a range or numbers.

>sed '2 d' file.txt

>sed '5,$ d' file.txt

15. Duplicating lines
You can make the sed command to print each line of a file two times.

>sed 'p' file.txt

16. Sed as grep command
You can make sed command to work as similar to grep command.

>grep 'unix' file.txt

>sed -n '/unix/ p' file.txt

Here the sed command looks for the pattern "unix" in each line of a file and prints those lines that has the pattern.
You can also make the sed command to work as grep -v, just by using the reversing the sed with NOT (!).

>grep -v 'unix' file.txt

>sed -n '/unix/ !p' file.txt

The ! here inverts the pattern match.

17. Add a line after a match.
The sed command can add a new line after a pattern match is found. The "a" command to sed tells it to add a new line after a match is found.

>sed '/unix/ a "Add a new line"' file.txt

unix is great os. unix is opensource. unix is free os.

"Add a new line"

learn operating system.

unixlinux which one you choose.

"Add a new line"

18. Add a line before a match
The sed command can add a new line before a pattern match is found. The "i" command to sed tells it to add a new line before a match is found.

>sed '/unix/ i "Add a new line"' file.txt

"Add a new line"

unix is great os. unix is opensource. unix is free os.

learn operating system.

"Add a new line"

unixlinux which one you choose.

19. Change a line
The sed command can be used to replace an entire line with a new line. The "c" command to sed tells it to change the line.

>sed '/unix/ c "Change line"' file.txt

"Change line"

learn operating system.

"Change line"

20. Transform like tr command
The sed command can be used to convert the lower case letters to upper case letters by using the transform "y" option.

>sed 'y/ul/UL/' file.txt

Unix is great os. Unix is opensoUrce. Unix is free os.

Learn operating system.

UnixLinUx which one yoU choose.

Here the sed command transforms the alphabets "ul" into their uppercase format "UL"

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