Return exit code when host not found

[ispmarin]

When mtr is used on the command line and an invalid host is passed, mtr raises the message "Failed to resolve host: Name or service not known" but it returns 0, not -1 or any other code. Returning something different from zero when exiting the process with invalid host would make using it with other commands and pipes easier.

[rewolff]

Decided this would be a project I could finish in the time before I had to respond to "your're invited for diner, come now" .....
I followed the code, it exits with a failure code when this happens.
I tested the binary, and it returns an error code when this happens. In short: mtr works as you requested. I did test this on the most recent github version. maybe you're using somthing older?

[ispmarin]

Hi @rewolff, thanks for the feedback. Let me give you an example of what I'm talking about here, to see if helps:

If the command runs successfully, I get return code 0:

`:~$ mtr -C -c 3 terra.com.br
Mtr_Version,Start_Time,Status,Host,Hop,Ip,Loss%,Snt, ,Last,Avg,Best,Wrst,StDev,
MTR.0.87,1552385327,OK,terra.com.br,1,192.168.1.1,0.00,3,0,4.59,5.42,3.64,8.02,2.24
MTR.0.87,1552385327,OK,terra.com.br,2,10.75.128.1,0.00,3,0,11.69,11.53,11.38,11.69,0.00
MTR.0.87,1552385327,OK,terra.com.br,3,c952005a.virtua.com.br,0.00,3,0,12.91,12.55,11.90,12.91,0.00
MTR.0.87,1552385327,OK,terra.com.br,4,c9520008.virtua.com.br,0.00,3,0,27.96,17.79,12.14,27.96,8.80
MTR.0.87,1552385327,OK,terra.com.br,5,c952005a.virtua.com.br,0.00,3,0,14.95,14.27,12.54,15.33,1.22
MTR.0.87,1552385327,OK,terra.com.br,6,embratel-t0-4-0-6-uacc01.cas.embratel.net.br,0.00,3,0,14.04,14.84,14.04,15.26,0.00
MTR.0.87,1552385327,OK,terra.com.br,7,ebt-h0-0-0-0-tcore01.cas.embratel.net.br,0.00,3,0,17.65,15.68,14.06,17.65,1.58
MTR.0.87,1552385327,OK,terra.com.br,8,ebt-b11951-intl01.atl.embratel.net.br,0.00,3,0,129.85,133.75,129.85,137.92,3.94
MTR.0.87,1552385327,OK,terra.com.br,9,ix-et-10-0-2-0.tcore2.a56-atlanta.as6453.net,0.00,3,0,146.52,147.48,146.52,148.38,0.71
MTR.0.87,1552385327,OK,terra.com.br,10,if-ae-14-2.tcore2.mln-miami.as6453.net,0.00,3,0,163.09,163.41,162.75,164.40,0.71
MTR.0.87,1552385327,OK,terra.com.br,11,if-ae-1-2.tcore1.mln-miami.as6453.net,0.00,3,0,163.48,164.81,163.48,166.76,1.58
MTR.0.87,1552385327,OK,terra.com.br,12,63.243.152.142,0.00,3,0,157.73,156.80,155.98,157.73,0.71
MTR.0.87,1552385327,OK,terra.com.br,13,84.16.12.136,0.00,3,0,155.04,154.71,154.22,155.04,0.00
MTR.0.87,1552385327,OK,terra.com.br,14,84.16.9.130,0.00,3,0,154.46,154.55,153.70,155.47,0.71
MTR.0.87,1552385327,OK,terra.com.br,15,66.119.65.193,0.00,3,0,154.49,155.25,154.15,157.12,1.41
MTR.0.87,1552385327,OK,terra.com.br,16,216.177.213.250,0.00,3,0,163.04,164.07,163.04,165.97,1.41
MTR.0.87,1552385327,OK,terra.com.br,17,terra-v-95-srx-mia.tc.terra.com,0.00,3,0,154.07,154.71,154.07,155.19,0.00
MTR.0.87,1552385327,OK,terra.com.br,18,www.terra.com.br,0.00,3,0,163.93,164.68,163.75,166.38,1.22

:~$ echo $?
0
`

So it returns 0, as expected. Let's try now a host that doesn't exist:
`
:~$ mtr -C -c 3 terra.com.br2
Failed to resolve host: Name or service not known

:~$ echo $?
0
`
so this host doesn't exist, but the command still returns 0. Maybe it's something on my version, as I'm using Debian stable:

dpkg -l | grep mtr ii mtr 0.87-1 amd64 Full screen ncurses and X11 traceroute tool
Thanks.

[rewolff]

It has something to do with the options you're passing!

getafix:~/mtr> ./mtr -C -c 3 terra.com.br2
./mtr: Failed to resolve host: terra.com.br2: Name or service not known
getafix:~/mtr> echo $?
0
getafix:~/mtr> ./mtr terra.com.br2
./mtr: Failed to resolve host: terra.com.br2: Name or service not known
getafix:~/mtr> echo $?
1
getafix:~/mtr> 

[Mike-S-BA]

Any chance this may get fixed?

[patrykcieszkowski]

I can confirm that --raw flag causes the mtr to exit with code 0, even on unresolved hostname error.