capture output of ssh remote command

mvalsasna · Tue Jan 03, 2017 11:50 am

Hi

I'm trying to connect from one router to another to get wifi signal-strength

:global GoldenUser; :global GoldenIP
:local myMac E4:8D:8C:26:DC:03
do {
    :local out [[ /system ssh user=$GoldenUser $GoldenIP ":put [/interface wireless registration-table get [ find mac-address=$myMac ]  signal-strength ]" ]]
    :put "out:$out:"
} on-error={
    :put "ERR"
}

but when I run the script it seems that the remote command is run but, it does not generate an error, but its output is not captured.
looks like /system ssh sends the remote command output to stderr instead of stdout, so it is printed to console but not captured by the script

/system script> run test         
-78dBm@6Mbps

Welcome back!
out::

any hints?

thanks

MAtteo

Sinan · Wed Jan 04, 2017 10:52 pm

Try to put the result in a file then get it by fetch tool

mvalsasna · Tue Jan 10, 2017 4:09 pm

not sure if there is a feature to redirect the output to a file (afterall, routeros is Linux-based).
can you try this..
Code: Select all
/system script> run test file=someoutput.txt
and see if that is what you need?

parameter is not supported:

[toor@PEAMI-GW] /system script> run test file=someoutput.txt
expected end of command (line 1 column 10)

version: 6.36.4 (bugfix)

Tue Jan 10, 2017 4:53 pm

SSH command output can be saved with "output-to-file" option.

Any other script/command output you can save with :execute command:

For example - save output of your script:

The script:
/system script add name=ScriptExample source={
/system clock print
}

Execute script, and save output:
{:local a [/system script get ScriptExample source]; execute script=$a file=OutputOfScript}

Or simply save output of any command:
:execute script={/system clock print} file=OutputOfCommand

mvalsasna · Tue Jan 10, 2017 7:12 pm

SSH command output can be saved with "output-to-file" option.

1) true, thanks (meanwhile I had found it out too)

2) but there is another quirk: the file content is not immediately available, you need to insert a delay between creating the file and reading it (sic):

:global GoldenUser; :global GoldenIP;
:local filename outfile
:local myMac E4:8D:8C:26:DC:03
#:local myMac 04:F0:21:1D:77:70
do {
/file remove out
} on-error={
    :put "file already deleted"
}
do {
    /system ssh user=$GoldenUser $GoldenIP ":put [/interface wireless registration-table get [ find mac-address=$myMac ]  signal-strength ]" output-to-file=$filename
} on-error={
    :put "ERR"
}
:delay 1
:local result 
:set result [ /file get [ find name=$filename ] contents ]
:put "res:$result:$filename"

(without :delay the script fails!)

3) this script runs fine from the console, but not if launched remotely via SSH:

from console:

[root@router] /system script> run test         
file already deleted

Welcome back!
res:-85dBm@6Mbps
:outfile

launching from SSH, the outbound ssh connection seems to fail (out file is not created)

$ ssh root@ROUTER_IP "/system script run test"
root@ROUTER_IP's password: 
file already deleted
ERR
res:-85dBm@6Mbps
:outfile

any hint on why this happens/how to fix it?

5) also if I run the script trough :execute it fails to connect via ssh

[root@router] /system script> {:local a [/system script get test  source]; :execute script=$a file=OutputOfScript} 
[root@router] /system script> :put [ /file get OutputOfScript.txt  contents ]                                      
file already deleted
ERR
no such item

it seems that there is something really hard about using outbound SSH in a script, or possibly this could be the result of some security measure

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