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Double quotes or single quotes when using ssh?

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# 1  
Old 05-28-2008
Double quotes or single quotes when using ssh?

I'm not very familiar with the ssh command. When I tried to set a variable and then echo its value on a remote machine via ssh, I found a problem. For example,

$ ITSME=itsme
$ ssh "ITSME=itsyou; echo $ITSME"
$ ssh 'ITSME=itsyou; echo $ITSME'

So what was going on here? Which satement was executed on remote machine and which one was on local system? I'm a little confused ....
# 2  
Old 05-28-2008
Check the links below.
# 3  
Old 05-28-2008
Double quotes don't prevent variables from being expanded locally. So the remote host sees "ITSME=itsyou; echo itsme" in the first case.
# 4  
Old 05-29-2008
Originally Posted by era
Double quotes don't prevent variables from being expanded locally. So the remote host sees "ITSME=itsyou; echo itsme" in the first case.
So the two statements: ITSME=itsyou & echo $ITSME are both executed on remote host. But in the case of double quotes, variable will be evaluated first so the argument passed to ssh is actually ITSME=itsyou; echo itsme. While in the case of single quotes, no special characters survive. The argument passed to ssh is ITSME=itsyou; echo $ITSME. Understood, this is really an issue of command-line processing.

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