Retrieving the result of a bash command run from ssh into a variable

Question

The following command runs well when i run it localy on the dsired machine:

app_name=*some_proccess_name*
pid=`pgrep $app_name | tail -n 1`

But when i run it in the following way, from a remote pc using ssh it dosn't work:

pid=$(ssh $USER_NAME@$HOST_NAME "echo `pgrep $app_name | tail -n 1`")

The value of pid afterwards is just blank. I am not sure what's wrong (just to clarify i have tried several processes names that are all running on the target pc- that's not the problem ).

P.S when i run the command without echo, like that, i just get stuck inside the remote pc and have to use exit in order to get unstuck and return to my local pc:

pid=$(ssh tester@mir1 "`pgrep indicator-apple | tail -n 1`")

When you write, "`pgrep indicator-apple | tail -n 1`" with backticks inside double quotes, your shell will run that command as a subshell and then send the result of that command as an extra argument to ssh. Remove the backticks, they are unnecessary: pid=$(ssh tester@mir1 "pgrep indicator-apple | tail -n 1") — 0x5453
– 0x5453, Commented May 23, 2017 at 19:09

Diego Torres Milano · Accepted Answer · 2017-05-23 19:06:38Z

3

Less is more

pid=$(ssh tester@mir1 pgrep indicator-apple \| tail -n 1)

answered May 23, 2017 at 19:06

Diego Torres Milano

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1 Comment

chepner Over a year ago

I'd recommend explicitly quoting the entire thing, not just the pipe character; ssh combines multiple arguments into a single command string in a non-terribly-well-defined way, so you may as well do it yourself. ssh tester@mir1 'pgrep indicator-apple | tail -n 1'

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