Substract number from wc cmd in one line

Question

Let's suppose test.csv contains 10 lines. I'd like to put 9 into output.txt in one command line. I tried:

cat test.csv | $(wc -l) - 1 > output.txt

output.txt should contain 9.

What should `output.txt` contain when `wc -l` outputs `0` for an empty file - `-1` or something else? — Ed Morton, Nov 19 '20 at 21:04

score 4 · Accepted Answer · answered Nov 19 '20 at 19:07

4

echo $(( $(wc -l <test.csv) - 1 )) > output.txt

or

wc -l <test.csv | awk '{$1--}1' > output.txt

answered Nov 19 '20 at 19:07

KamilCuk

score 1 · Answer 2 · answered Nov 19 '20 at 19:26

1

Or just the good old-fashioned:

expr $(wc -l < test.csv) - 1

answered Nov 19 '20 at 19:26

William Pursell

score 0 · Answer 3 · answered Nov 19 '20 at 19:20

0

Use this Perl one-liner:

perl -le 'print `wc -l <test.csv` - 1' > output.txt

answered Nov 19 '20 at 19:20

Timur Shtatland

3 Answers3