Re: [PATCH iproute2-next] "ip help" wrong output, exit code.

[Dmitri Seletski <drjoms@gmail.com>]

Hello David,


Based on change introduced:

Two samples of "ip help" with demonstration of exit code and standard 
output are below.

This is in line with what expect.


dimkosPC~/compiled/iproute2-next #if ./ip/ip help a >>/dev/null  ; then 
echo help triggered  ; else echo error code triggered  ;fi  #this 
redirects standard output  to /dev/null, so text missing is not error,
but standard text
help triggered

dimkosPC~/compiled/iproute2-next #if ./ip/ip help   ; then echo help 
triggered  ; else echo error code triggered  ;fi
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
       ip [ -force ] -batch filename
where  OBJECT := { address | addrlabel | fou | help | ila | ioam | l2tp 
| link |
                   macsec | maddress | monitor | mptcp | mroute | mrule |
                   neighbor | neighbour | netconf | netns | nexthop | 
ntable |
                   ntbl | route | rule | sr | stats | tap | tcpmetrics |
                   token | tunnel | tuntap | vrf | xfrm }
       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
                    -h[uman-readable] | -iec | -j[son] | -p[retty] |
                    -f[amily] { inet | inet6 | mpls | bridge | link } |
                    -4 | -6 | -M | -B | -0 |
                    -l[oops] { maximum-addr-flush-attempts } | -echo | 
-br[ief] |
                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch] 
[filename] |
                    -rc[vbuf] [size] | -n[etns] name | -N[umeric] | -a[ll] |
                    -c[olor]}
help triggered

Two samples of command that is broken on purpose.

dimkosPC~/compiled/iproute2-next #if ./ip/ip idontexist   ; then echo 
help triggered  ; else echo error code triggered  ;fi
Object "idontexist" is unknown, try "ip help".
error code triggered

dimkosPC~/compiled/iproute2-next #if ./ip/ip idontexist  >>/dev/null  ; 
then echo help triggered  ; else echo error code triggered  ;fi  #this 
redirects standard output  to /dev/null, so text missing is not error, 
but standard text
Object "idontexist" is unknown, try "ip help".
error code triggered

This works as expected as per my understanding.


Not everything is fixed, but chunk of things fixed is better than non of it.

for example:

if ip  add help    ; then echo help triggered  ; else echo error code 
triggered  ;fi  #this redirects standard output  to /dev/null, so text 
missing is not error, but standard text
Usage: ip address {add|change|replace} IFADDR dev IFNAME [ LIFETIME ]
                                                      [ CONFFLAG-LIST ]
       ip address del IFADDR dev IFNAME [mngtmpaddr]
       ip address {save|flush} [ dev IFNAME ] [ scope SCOPE-ID ] [ to 
PREFIX ]
                            [ FLAG-LIST ] [ label LABEL ] [ { up | down } ]
       ip address [ show [ dev IFNAME ] [ scope SCOPE-ID ] [ master DEVICE ]
                         [ nomaster ]
                         [ type TYPE ] [ to PREFIX ] [ FLAG-LIST ]
                         [ label LABEL ] [ { up | down } ] [ vrf NAME ]
                         [ proto ADDRPROTO ] ]
       ip address {showdump|restore}
IFADDR := PREFIX | ADDR peer PREFIX
          [ broadcast ADDR ] [ anycast ADDR ]
          [ label IFNAME ] [ scope SCOPE-ID ] [ metric METRIC ]
          [ proto ADDRPROTO ]
SCOPE-ID := [ host | link | global | NUMBER ]
FLAG-LIST := [ FLAG-LIST ] FLAG
FLAG  := [ permanent | dynamic | secondary | primary |
           [-]tentative | [-]deprecated | [-]dadfailed | temporary |
           CONFFLAG-LIST ]
CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG
CONFFLAG  := [ home | nodad | mngtmpaddr | noprefixroute | autojoin ]
LIFETIME := [ valid_lft LFT ] [ preferred_lft LFT ]
LFT := forever | SECONDS
ADDRPROTO := [ NAME | NUMBER ]
TYPE := { amt | bareudp | bond | bond_slave | bridge | bridge_slave |
          dsa | dummy | erspan | geneve | gre | gretap | gtp | hsr |
          ifb | ip6erspan | ip6gre | ip6gretap | ip6tnl |
          ipip | ipoib | ipvlan | ipvtap |
          macsec | macvlan | macvtap | netdevsim |
          netkit | nlmon | pfcp | rmnet | sit | team | team_slave |
          vcan | veth | vlan | vrf | vti | vxcan | vxlan | wwan |
          xfrm | virt_wifi }
error code triggered

This is still problematic.


But so far code leaves "ip help" command/argument in better shape than 
it found it in.


I may try improve things more, but lets submit what we already have 
"better", please.

Kind Regards

Dmitri Seletski


On 6/22/26 17:44, David Laight wrote:
> On Mon, 22 Jun 2026 07:57:00 -0700
> Stephen Hemminger <stephen@networkplumber.org> wrote:
>
>> On Sun, 21 Jun 2026 22:48:59 +0100
>> Dmitri Seletski <drjoms@gmail.com> wrote:
>>
>>>  From 0805e07105cd15c5b94271a4706e50e3c65dbde5 Mon Sep 17 00:00:00 2001
>>> From: Dmitri Seletski <drjoms@gmail.com>
>>> Date: Sun, 21 Jun 2026 22:12:43 +0100
>>> Subject: [PATCH iproute2-next]  "ip help" wrong output, exit code.
>>>
>>> Changed output of "ip help" from standard error to standard output. And
>>> Exit is now 0 instead of -1. "ip help|grep bridge" - now gives bridge
>>> syntax instead of flooding user with everything from "ip help".
>>> ---
>>> ip/ip.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/ip/ip.c b/ip/ip.c
>>> index e4b71bde..4627b61c 100644
>>> --- a/ip/ip.c
>>> +++ b/ip/ip.c
>>> @@ -56,7 +56,7 @@ static void usage(void) __attribute__((noreturn));
>>>
>>> static void usage(void)
>>> {
>>> -fprintf(stderr,
>>> +fprintf(stdout,
>>> "Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }\n"
>>> "       ip [ -force ] -batch filename\n"
>>> "where  OBJECT := { address | addrlabel | fou | help | ila | ioam | l2tp
>>> | link |\n"
>>> @@ -72,7 +72,7 @@ static void usage(void)
>>> "                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch]
>>> [filename] |\n"
>>> "                    -rc[vbuf] [size] | -n[etns] name | -N[umeric] |
>>> -a[ll] |\n"
>>> "                    -c[olor]}\n");
>>> -exit(-1);
>>> +exit(0);
>>> }
>> Your mailer damages white space.
>>
> The output also needs to depend on whether these is a 'usage' error or
> if 'help' is requested.
> Code code is correct for the former - except it should do exit(1).
>
> 	David
>
>