Not empty file, but “wc -l” outputs 0

Question

I have a non-empty file (even a big one, 400Ko ), that I can read with less .

But if I try to output the number of lines with wc -l /path/to/file it outputs 0 .

How can it be possible?

Answer 1

You can verify for yourself that the file contains no newline/linefeed (ASCII 10) characters, which would result in wc -l reporting 0 lines.

1. First, count the characters in your file:

    wc -c /path/to/file

   You should get a non-zero value.

2. Now, filter out everything that isn't a newline:

    tr -dc '\\n' /path/to/file | wc -c

   You should get back 0.

3. Or, delete the newlines and count the result.

    tr -d '\\n' | wc -c

   You should get back the same value as in step 1.

Answer 2

wc counts number of '\\n' characters in the file. Could it be that your file does not contain one?

Here is the GNU source: https://www.gnu.org/software/cflow/manual/html_node/Source-of-wc-command.html

look for COUNT(c) macro.

Answer 3

Here's one way it's possible. Make a 400k file with just nulls in it:

dd if=/dev/zero bs=1024 count=400 of=/tmp/nulls ; ls -log /tmp/nulls 

Output shows the file exists:

400+0 records in
400+0 records out
409600 bytes (410 kB, 400 KiB) copied, 0.00343425 s, 119 MB/s
-rw-rw-r-- 1 409600 Feb 28 11:12 /tmp/nulls

Now count the lines:

wc -l /tmp/nulls
0 /tmp/nulls

Answer 4

It is possible if the HTML file is minified . The newline characters would have been removed during minification of the content.

Try with file command,

file filename.html

filename.html: HTML document text, UTF-8 Unicode text, with very long lines, with no line terminators