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

Here is a solution that removes all lines that are either blank or contain only space characters:

grep -v '^[[:space:]]*$' foo.txt

Answer 2

grep . FILE

---

(And if you really want to do it in sed, then: sed -e /^$/d FILE)

(And if you really want to do it in awk, then: awk /./ FILE)

Answer 3

grep '^..' my_file

example

THIS

IS

THE

FILE

EOF_MYFILE

it gives as output only lines with at least 2 characters.

THIS
IS
THE
FILE
EOF_MYFILE

See also the results with grep '^' my_file outputs

THIS

IS

THE

FILE

EOF_MYFILE

and also with grep '^.' my_file outputs

THIS
IS
THE
FILE
EOF_MYFILE

Answer 4

If you want to know what the total lines of code is in your Xcode project and you are not interested in listing the count for each swift file then this will give you the answer. It removes lines with no code at all and removes lines that are prefixed with the comment //

Run it at the root level of your Xcode project.

find . \( -iname \*.swift \) -exec grep -v '^[[:space:]]*$' \+ | grep -v -e '//' | wc -l

If you have comment blocks in your code beginning with /* and ending with */ such as:

/*
 This is an comment block 
*/

then these will get included in the count. (Too hard).

Answer 5

Perl might be overkill, but it works just as well.

Removes all lines which are completely blank:

perl -ne 'print if /./' file

Removes all lines which are completely blank, or only contain whitespace:

perl -ne 'print if ! /^\s*$/' file

Variation which edits the original and makes a .bak file:

perl -i.bak -ne 'print if ! /^\s*$/' file

Answer 6

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

---

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