How to programatically remove empty new lines from a file?

Question

I need to remove empty new lines from text file in terminal.

Example file

123
123
123
123

123



123

I've searched in google a bit but only solution found was sed '/^$/d' myFile > tt and it does not help. I still got these empty new lines.

Answer 1

You can use grep for this purpose.

Try: grep -v ^$ filename.

---

Your command also seems to work:

$ cat t
123
123
123
123

123



123
$ sed '/^$/d' t
123
123
123
123
123
123
$ sed '/^$/d' t >tt
$ cat tt
123
123
123
123
123
123
$

Answer 2

The solution you posted will delete empty lines:

sed '/^$/d' myFile > output

This won't work for lines that contain spaces, or hard tabs, or any other kind of whitespace, including carriage returns. This means, if your text file originated on Windows, that solution probably won't work.

On Unix, lines are simply separated with a line feed. On Windows, they are separated with a carriage return and a line feed.

Here's one way to delete empty lines, compatible with Windows' text format:

sed '/^\x0D\?$/d' myFile > output

If you want to delete lines that contain only whitespace, this should work (on Ubuntu at least):

sed -r '/^\s*\x0D?$/d' myFile > output

Answer 3

There's probably a 100 ways to do this, this is one:

grep -vE "$^" yourfile

Answer 4

Here's another solution:

python -c "import sys; print ''.join(line for line in sys.stdin.readlines() if line.strip() != ''),"

(python is installed by default)

Answer 5

Using AWK: NF is AWK's in-built variable that stores the number of fields in each record. When used by it self, it will print only those lines where NF!=0.

[jaypal~/Temp]$ cat t
123
123
123
123

123



123

[jaypal~/Temp]$ awk 'NF' t
123
123
123
123
123
123