On Mon, 28 Dec 2015 18:47:51 -0500 Nathaniel W Filardo <n...@cs.jhu.edu> wrote:
> Hallo netdev@,
>
> I had occasion to want to programmatically wait for an interface to become
> available from within a shell script, but found there to be no off-the-shelf
> tool for such a thing. Could this patch be considered for inclusion as part
> of iproute2? It adds an "ip wait link" subcommand ("link" required in case
> someone wants to add things like "ip wait addr" or somesuch) based quite
> heavily on the ipmonitor.c file.
>
> For example, one might "ip wait link dev eth0 up" to wait for an interface
> of that name to appear (specifically, for a RTM_NEWLINK message). "ip wait
> link dev eth0 down" will wait for it to go away (RTM_DELLINK).
>
> This should be checkpatch clean, but please let me know if I missed
> something.
>
> Cheers,
> --nwf;
>
Thank you for your contribution, it looks useful.
Could you also update the man page?
> +static int accept_msg(const struct sockaddr_nl *who,
> + struct rtnl_ctrl_data *ctrl,
> + struct nlmsghdr *n, void *arg)
> +{
> + int done = 0;
> +
> + if (n->nlmsg_type == RTM_NEWLINK || n->nlmsg_type == RTM_DELLINK) {
> + if (wait_for == n->nlmsg_type
> + && wait_for == RTM_DELLINK
> + && ll_name_to_index(wait_dev) != 0)
> + done = 1;
> +
> + ll_remember_index(who, n, NULL);
> + if (verbose)
> + print_linkinfo(who, n, stdout);
> +
> + if (wait_for == n->nlmsg_type
> + && wait_for == RTM_NEWLINK
> + && ll_name_to_index(wait_dev) != 0)
> + done = 1;
> + }
> + if (done) {
> + fflush(stdout);
> + exit(0);
I don't think you need explicit fflush here. Stdio does it automatically.
Which means all the conditional(done) can be removed.
Have you considered how wait could be used with --batch option
to write a script?
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