Sed (Stream Editor) Command: -

Q) What is the use of sed command ?

Ans – There are three different tasks of sed command.

1.       Printing

2.       Deleting

3.       Substituting

Q) How to print 5^th line of a file f1 ?

Ans - $ sed –n ‘5p’ f1<Enter – Key>

Q) How to print 12^th to 33^rd lines from a file file.sh ?

Ans - $ sed –n ’12,33p’ file.sh<Enter – Key>

Q) What is the output of the command ?

$ sed –n ’10,5p’ file1<Enter – Key>

Ans – It will print only 10^th line of the file file1

Q) What is the output of the command ?

$ sed –n ’10,+5p’ file1<Enter – Key>

Ans – It will print 10^th line and next 5 lines.

Q) What is the output of the command ?

$ sed –n ’1~4p’ file1<Enter – Key>

Ans – It will print 1^st line and then skips 2^nd, 3^rd , 4^th lines and print 5^th Line, then skips 6^th , 7^th , 8^th lines and print 9^th line and continues till end of the file.

Q) What is the output of the command ?

$ sed –n ’2,5!p’ file1<Enter – Key>

Ans – It will print everything except 2^nd to 5^th lines.

Q) What is the output of the command ?

$ sed –n ’2,p’ file1<Enter – Key>

Ans - Error

Q) What is the output of the command ?

$ sed –n ’,5p’ file1<Enter – Key>

Ans – Error

Q) How to print header or 1^st line of the file f1 ?

Ans - $ sed –n ‘1p’ f1<Enter – Key>

Q) How to print footer or last line of the file f1 ?

Ans - $ sed –n ‘$p’ f1<Enter – Key>

Q) How to print both header and footer of the file f1 in one command ?

Ans - $ sed –n ‘1p;$p’ f1<Enter – Key>

Q) How to print 10 to 20, 30 to 50 and 43^rd lines of a file f1 ?

Ans - $ sed –n ’10,20p;30,50p;43p’ f1<Enter – Key>

Q) How to temporarily delete 5^th line of a file f1 ?

Ans - $ sed –e ‘5d’ f1<Enter – Key>

Q) How to temporarily delete 12^th to 33^rd lines from a file file.sh ?

Ans - $ sed –e ’12,33d’ file.sh<Enter – Key>

Q) What is the output of the command ?

$ sed –e ’10,5d’ file1<Enter – Key>

Ans – It will temporarily delete only 10^th line of the file file1

Q) What is the output of the command ?

$ sed –e ’10,+5d’ file1<Enter – Key>

Ans – It will temporarily delete 10^th line and next 5 lines.

Q) What is the output of the command ?

$ sed –e ’1~4d’ file1<Enter – Key>

Ans – It will temporarily delete 1^st line and then prints 2^nd, 3^rd , 4^th lines and temporarily delete 5^th Line, then prints 6^th , 7^th , 8^th lines and temporarily delete 9^th line and continues till end of the file.

Q) What is the output of the command ?

$ sed –e ’2,5!d’ file1<Enter – Key>

Ans – It will temporarily delete everything except 2^nd to 5^th lines.

Q) What is the output of the command ?

$ sed –e ’2,d’ file1<Enter – Key>

Ans - Error

Q) What is the output of the command ?

$ sed –e ’,5d’ file1<Enter – Key>

Ans – Error

Q) How to temporarily delete header or 1^st line of the file f1 ?

Ans - $ sed –e ‘1d’ f1<Enter – Key>

Q) How to temporarily delete footer or last line of the file f1 ?

Ans - $ sed –e ‘$d’ f1<Enter – Key>

Q) How to temporarily delete both header and footer of the file f1 in one command ?

Ans - $ sed –e ‘1d;$d’ f1<Enter – Key>

Q) How to temporarily delete 10 to 20, 30 to 50 and 43^rd lines of a file f1 ?

Ans - $ sed –e ’10,20d;30,50d;43d’ f1<Enter – Key>

Q) How to permanently delete 5^th line of a file f1 ?

Ans - $ sed –i ‘5d’ f1<Enter – Key>

Q) How to permanently delete 15^th to 23^rd lines of a file f1 ?

Ans - $ sed –i ’15,23d’ f1<Enter – Key>

Q) How to substitute bad with word good in all positions of the file f1 ?

Ans - $ sed ‘s/bad/good/g’ f1<Enter – Key>

Where g – globally

Q) How to substitute bad with good word from 3^rd to last field of file f1 ?

Ans - $ sed ‘s/bad/good/3g’ f1<Enter – Key>

Q) How to substitute bad with good word in 2^nd field position of file f1 ?

Ans - $ sed ‘s/bad/good/2’ f1<Enter – Key>

Q) How to substitute bad with good word in 1^st field position of file f1 ?

Ans - $ sed ‘s/bad/good/1’ f1<Enter – Key>

Q) How to substitute bad with good word from 3^rd to last field of file f1  between 15^th to 23^rd lines ?

Ans - $ sed ’15,23s/bad/good/3g’ f1<Enter – Key>

Q) How to substitute bad with good word in 2^nd field position of file f1 at a line number 45 ?

Ans - $ sed ‘45s/bad/good/2’ f1<Enter – Key>

Q) How to replace the 5^th occurance of 3^rd line of is with are in file f1 ?

Ans - $ sed ‘3s/is/are/5’ f1<Enter – Key>

Q) How to print blank lines ?

Ans - $ sed –n ‘^$p’ filename<Enter – Key>