Re: device cannot be completed after "ip link show dev"

[Han Pingtian <hanpt@linux.vnet.ibm.com>]

On Tue, Mar 31, 2015 at 07:57:01PM +0100, Peter Stephenson wrote:
> On Mon, 30 Mar 2015 11:39:30 +0800
> Han Pingtian <hanpt@linux.vnet.ibm.com> wrote:
> > Although in _ip() the "link_show_cmds" is defined to
> > 
> > 188 local -a link_show_cmds
> > 189 _regex_words link-show-commands 'link show commands' \
> > 190   'dev:specify device:$subcmd_dev' \
> > 191   'up:limit display to running devices'
> > 192 link_show_cmds=("(" $subcmd_dev "|" ")" "$reply[@]" "#" )
> > 193 
> > 
> > but the device cannot be completed after "ip link show dev":
> 
> I see the problem: we're matching way too much where we think there
> might be a dev already on the command line.
> 
What's going on when

% ip link show dev <tab>

, please? It looks like the old pattern
/$'[[:alnum:][:punct:][:cntrl:][:digit:]]##\0'/ will match here, so the
action ':interfaces:network interface:_net_interfaces' will be bypassed?
But I think there is nothing at the position of <tab>, why the old
pattern would match a empty string?

> This is better.  There's still a possible glitch: if a device springs
> into existence dynamically we won't accept it as a device already part
> of the command line argument, though we will still complete it as that
> calls _net_interfaces again.  I think that's fairly minor.
> 
I have tested (by set a fake net_intf_list) that if there is a interface 
which named "dev", the completion will fail with this patch.

And I have figured out this works:

subcmd_dev=(
/$'[[:alnum:][:punct:][:cntrl:][:digit:]]##\0'/ 
-'if [[ $words[CURRENT-1] = dev ]];then false;else true;fi'
':interfaces:network interface:_net_interfaces'
)