Subject: bug#20928: cut (v. 8.21), using -f option with a single column

From: Stephane Chazelas <[email-masked]>
Date: Mon, 29 Jun 2015 16:54:19 +0100

2015-06-29 16:31:00 +0100, Pádraig Brady:
[...]
> > When there is only one column and we go beyond 1 with the -f option, the output remains the first column
> > 
> > $ echo "test1" | cut -d' ' -f1
> > test1
> > $ echo "test1" | cut -d' ' -f2
> > test1
> > $ echo "test1" | cut -d' ' -f3
> > test1
> 
> That difference in behavior is there for compat reasons.

Yes, and that's required by POSIX
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cut.html

> To induce the behavior you expect, you need the -s option.
[...]

-s suppresses the lines that don't have the field which is
different from outputting a blank field. Here, the OP more
likely wants:

paste -d ' ' - /dev/null | cut -d' ' -f3
(or awk -F'[ ]' '{print $3}')

$ printf '%s\n' a:b c d:e | cut -d: -f2
b
c
e
$ printf '%s\n' a:b c d:e | cut -sd: -f2
b
e
$ printf '%s\n' a:b c d:e | paste -d: - /dev/null | cut -d: -f2
b

e

-- 
Stephane