Remove empty lines in a text file via grep

Question

FILE:

hello

world

foo

bar

How can I remove all the empty new lines in this FILE?

Output of command:

Answer 1

If removing empty lines means lines including any spaces, use:

grep '\S' FILE

For example:

$  printf "line1\n\nline2\n \nline3\n\t\nline4\n" > FILE
$  cat -v FILE
line1

line2

line3

line4
$  grep '\S' FILE
line1
line2
line3
line4
$  grep . FILE
line1
line2

line3

line4

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See also:

• How to remove empty/blank lines (including spaces) in a file in Unix?
• How to remove blank lines from a file in shell?
• With sed: Delete empty lines using sed
• With awk: Remove blank lines using awk