Q. I want to change the formatting of a file. I just wanted to remove all blank lines from text file. How do I achieve this task w/o spending much time?
A. Yes, you do not have to waste your time making manual changes to files. Both Linux and UNIX systems come with file manipulation tools that can be used to remove all blank lines very quickly.
Task: Remove blank lines using sed
Type the following command:
$ sed '/^$/d' input.txt > output.txt
Task: Remove blank lines using grep
$ grep -v '^$' input.txt > output.txt
Both grep and sed use special pattern ^$ that matchs the blank lines. Grep -v option means print all lines except blank line.
Let us say directory /home/me/data/*.txt has all text file. Use following for loop (shell script) to remove all blank lines from all files stored in /home/me/data directory:
#!/bin/sh files="/home/me/data/*.txt" for i in $files do sed '/^$/d' $i > $i.out mv $i.out $i done
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