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up vote 2 down vote favorite

I have a list of servers 20+ that I would like to get the shell that they are using. While logged onto a server I can run the following command

$ ps -p $$
PID TTY          TIME CMD
12022 pts/6    00:00:00 bash

Instead of touching each server and doing this I tried to loop it with a list

$ for i in `cat servlist`; do echo $i ; ssh $i ps -p $$ ; done
serv1
PID TTY          TIME CMD
serv2
PID TTY          TIME CMD
serv3
PID TTY          TIME CMD

Looping this does not show the expected output. I then tried to ssh to a single server and run the command but got the same error.

$ ssh serv4 ps -p $$
PID TTY          TIME CMD

Why is this happening, nothing jumps out at me in the ssh man pages.

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1 Answer 1

up vote 3 down vote accepted

That is because the process does not exist.

The $$ is being evaluated locally, and all servers are being passed the same number. A number that is not a currently used PID on the servers.

All the $ stuff is done by the shell, not the commands. You need to escape it, so that it is evaluated by the shell on the server.

Try \$\$

e.g.

for i in $(cat servlist); do echo $i; ssh $i 'ps -p $$'; done

untested

share|improve this answer
    
I did not think to look more into the ps -p $$ command. When running for i in 'cat servlist'; do echo $i ; ssh $i ps -p \$\$ serv1 PID TTY TIME CMD 7199 ? 00:00:00 ps serv2 PID TTY TIME CMD 13842 ? 00:00:00 ps It did just occur to me to cat /etc/passwd | grep user" and find the default shell that way. –  Jon Wright Jun 22 at 21:41
1  
@JonWright getent passwd | awk -F: '$1=="user" {print $7}' will show you the login shell for "user". Is that what you wanted? –  roaima Jun 22 at 21:50
    
@roaima yes this is what I wanted. From habit I wanted to use ps -p $$. –  Jon Wright Jun 22 at 21:59
    
Top tip. use $(command) instead of (I can not type this) using back ticks. –  richard Jun 22 at 22:00

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