[ET Trac] [Einstein Toolkit] #545: Use ssh ProxyCommand instead of multiple ssh commands

[Einstein Toolkit]

#545: Use ssh ProxyCommand instead of multiple ssh commands
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  Reporter:  eschnett     |       Owner:  eschnett
      Type:  enhancement  |      Status:  review  
  Priority:  major        |   Milestone:          
 Component:  SimFactory   |     Version:          
Resolution:               |    Keywords:          
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Comment (by knarf):

 ssh proxies can be nested, however it turns out that the %h syntax is a
 problem here: every %h is replaced by ssh, regardless of quoting. Thus,
 simfactory would have to do that itself - which isn't a problem since that
 is known. Similarly for the port, but there simfactory would have to parse
 non-standard ports from given options.

 One example for -> numrel07 -> numrel08 -> queenbee would be:

 ssh -o ProxyCommand='ssh -o ProxyCommand='\''ssh numrel07.cct.lsu.edu nc
 numrel08.cct.lsu.edu %p'\'' numrel08.cct.lsu.edu nc qb.loni.org %p'
 qb.loni.org

 I agree with what you say about quoting. An empty string however, should
 not be quoted. It should always remain an empty string (although both
 options should work). It's not necessary and clutters the output,
 especially if these quotes are quoted again. An empty string, when passed
 to a shell, remains an empty string, regardless if quoted or not. Ideally,
 QuoteSafe would be able to tell if the argument needs quoting at all, and
 would only quote in that case - but of course that is optional.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/545#comment:5>
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