I have try to use sed command for delete particular line from file but it seems not working properly in my system (CentOS release 6.3 (Final).
my file1.txt contain following data

line1line2line3line4line5Now i try below command to delete 3rd line from the file.

$ sed '3d' file1.txt And output of above command is

line1line2line4line5But when i check original file then it seems nothing deleted. 3rd line is there.
So any one have idea why sed not working?

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