strange behaviour from sed???

alirezan · October 3, 2008, 7:39pm

Hi all,

I want to do a very simple thing with sed. I want to print out the line number of a disk I have defined in /etc/exports, so I do:

It's all good, but here's the problem. When I define md0 in a variable, I get nothing from sed:

Why is that? can anybody please help?

Thanks

joeyg · October 3, 2008, 8:28pm

> cat file9
/usr/bin/bash
/usr/bin/ksh
/usr/bin/me
/mdo/here/there
/jkl/lost/not
> dev=mdo
> echo $dev
mdo
> sed -n '/mdo/=' file9
4
> sed -n "/mdo/=" file9
4
> sed -n "/"$dev"/=" file9
4

cfajohnson · October 4, 2008, 6:19pm

alirezan:

Hi all,
Hi all,

I want to do a very simple thing with sed. I want to print out the line number of a disk I have defined in /etc/exports, so I do:
# sed -n '/md0/=' /etc/exports
3
It's all good, but here's the problem. When I define md0 in a variable, I get nothing from sed:
# dev="md0"
# echo $dev
md0
# sed -n '/$dev/=' /etc/exports
#
Why is that? can anybody please help?

Variables are not expanded inside single quotes; use double quotes:

sed -n "/$dev/=" /etc/exports