Introduce ifconfig -a -[gG] groupname

[eugen_grosbein.net]

Summary

Currently "ifconfig -a" command listing status of network interfaces may be accomplished with flags -d or -u to limit the list to interfaces that are down or up.

This change allows it to filter the list by name of interface group with additional flag -g groupname (or -G groupname to negate condition). Note this is different from "ifconfig -g groupname" that shows interface names only and that behaviour is not affected with the change.

groupname may contain shell patterns. Both -g and -G flags may be specified same time to apply both filters.

Test Plan

Examples:

to exclude loopback from the list: ifconfig -a -G lo
to show vlan interfaces only: ifconfig -a -g vlan
to show tap interfaces that are up: ifconfig -aug tap

[eugen_grosbein.net]

Fix misprint that somehow passed testing.

[eugen_grosbein.net]

Compactify code a bit.

[bcr]

Comment about caret escaping in a popular shell...

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

Sure the ^ is a special symbol with a very popular shell: zsh.
For example, I need to escape it every time I do an MFC like this:
$ svn merge -c r<revisionfromhead> \^/head/ stable/12

[eugen_grosbein.net]

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

Can you suggest another symbol that whould be suitable to zsh too? I don't have zsh to check.

[bcr]

Link to zshexpn with zsh-specific chars.

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

The zshexpn man page lists all the expansion characters in the "Word Designators" section. Everything that's not listed there should be fine.

[eugen_grosbein.net]

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

Which character would you personally like to use?

[bcr]

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

Maybe @ or #? The @ could be a mnemonic for "list me all AT this interface group".

[eugen_grosbein.net]

sbin/ifconfig/ifconfig.8

2925 ↗

(On Diff #72328)

As far as I know, # begins a commentary in any shell so it would require escaping too. The symbol @ may be suitable if we don't care that it would require escaping in Perl code running shell command.

I see only two other symbols that could also do it, a colon (:) or slash (/). I think we need more opinions.

[ae]

You can just use another option name to specify excludes.

[eugen_grosbein.net]

In D25029#551705, @ae wrote:

You can just use another option name to specify excludes.

Good point, -G would do it for negation.

[donner]

In D25029#551707, @eugen_grosbein.net wrote:

In D25029#551705, @ae wrote:

You can just use another option name to specify excludes.

Good point, -G would do it for negation.

+1 for "-G"
Usually negation in a´shell arguments is prefixed by "!", which needs to be escaped.
"^" does look like an regex starting point and will cause confusion: "Why is '-g la.*2[345]' not working?"

[eugen_grosbein.net]

In D25029#552131, @lutz_donnerhacke.de wrote:

"^" does look like an regex starting point and will cause confusion: "Why is '-g la.*2[345]' not working?"

You gave me an idea to use fnmatch() instead of strcmp for matching against group name. Thanks!

[eugen_grosbein.net]

Do not use prefix to negate condition. Instead, use new flag -G and allow user to specify both -g and -G same time.

[eugen_grosbein.net]

Fix case when none of -g nor -G is specified that was broken with addition of second option.

[donner]

If I understand correctly

ifconfig -a -g lagg -G lagg*1

will match all lagg interfaces besides those ending in 1.

But

ifconfig -a -g lagg -g vlan

will match vlan interfaces only.

Correct?

[eugen_grosbein.net]

Add explicit note to the manual page that additional options -g override previous ones, same for -G.

[eugen_grosbein.net]

In D25029#552845, @lutz_donnerhacke.de wrote:

If I understand correctly

ifconfig -a -g lagg -G lagg*1

will match all lagg interfaces besides those ending in 1.

But

ifconfig -a -g lagg -g vlan

will match vlan interfaces only.

Correct?

Yes. I've updated change to the manual page with explicit note.

[eugen_grosbein.net]

I'm going to commit this soon unless an objection is raised.

I'd like to hear something from manpages about syntax and wording.

[bcr]

Small wording fixes in the man page.

ifconfig.8

2923 ↗

(On Diff #72567)

s/of specified/of the specified/
same below

2933 ↗

(On Diff #72567)

s/later overrides/later ones override/
s/one/ones/

3062 ↗

(On Diff #72567)

s/loopack/loopback/

[eugen_grosbein.net]

Correct wording in the manual page.

[eugen_grosbein.net]

Thanks!

[bcr]

OK from manpages. Ready to go. Thanks for having this constructive review!