Can't use Linux wc on one-line file

Question

I have a one-line file with no newline character at the end of the line. When i run the following:

diff oneline-file.txt any-file.txt | wc -c

I get:

Warning: missing newline character in oneline-file.txt

Why is this an error? How can i fix it? I could do this first:

echo "\n" >> oneline-file.txt

I'd rather do something that does not change the file. Thx.

What version of `diff` is this? I don't get that warning, but the output has `\ No newline at end of file`. — Barmar, Apr 20 '18 at 00:59
`echo "\n"` won't echo a newline, it will echo that literal string. — Barmar, Apr 20 '18 at 01:01

score 0 · Accepted Answer · answered Apr 20 '18 at 02:35

0

Thanks to Barmar. This steered me in the right direction. Here's what I used:

diff <(sed 's/$/\n/g' oneline-file.txt) <(cat any-file.txt) | wc -c

answered Apr 20 '18 at 02:35

JRomeo

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score -1 · Answer 2 · answered Apr 20 '18 at 00:58

-1

You could pipe the result of your echo into diff, replacing the file name as an argument to diff with - (telling it to get that input from stdin).

answered Apr 20 '18 at 00:58

Scott Hunter

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score -1 · Answer 3 · answered Apr 20 '18 at 01:00

-1

You can use process substitution to echo the newline after the file:

diff <(cat oneline-file.txt; echo "") any-file.txt | wc -c

answered Apr 20 '18 at 01:00

Barmar

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Can't use Linux wc on one-line file

3 Answers3