Why isn't this sed regex matching?

Question

I've recently started learning sed. I did

$seq 10 | sed '/[^049]/d'

I was expecting

4 
9
10

as output. But I got

4
9

Where am I making mistake in understanding this regex?

cjm · Accepted Answer · 2011-04-27 02:21:15Z

up vote 4 down vote accepted

The 1 in the number 10 matches [^049] so it's deleted.

edited Apr 27 '11 at 2:21

cjm
8,51611828

answered Apr 27 '11 at 2:02

mmckinst
2,5501412

Whoops. That was foolish of me to ask here. :( Thanks by the way. – Dharmit Shah Apr 27 '11 at 2:09

1

Minor tip: Bracketing your regex with ^ and $ is useful to ensure that you're always looking at the whole string. – l0b0 Apr 27 '11 at 9:48

pepoluan · Answer 2 · 2011-04-27 14:51:16Z

If you really want to show lines containing '0', '4', or '9', here's how:

seq 10 | sed -n '/[049]/p'

The -n instructs sed to not print any lines. The p command instructs sed to print lines matching the /regex/

Alternatively, you can always use grep :-)

seq 10 | grep -E "[049]"

2 Answers