Why is the command not gettng the input with pipe in bash? - bash

Question

I am trying to do something simple in bash but I cannot get it to work. I have defined the variable:
export devcluster2="10.122.22.22"
in my .bashrc. When I type:
echo $devcluster2 I get as expected:
10.122.22.22
now I want to do:
echo '$devcluster2' | ssh
but I get
usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]
[-D [bind_address:]port] [-e escape_char] [-F configfile]
[-I pkcs11] [-i identity_file]
[-L [bind_address:]port:host:hostport]
[-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
[-R [bind_address:]port:host:hostport] [-S ctl_path]
[-W host:port] [-w local_tun[:remote_tun]]
[user#]hostname [command]
I want to understand why the ssh doesn't get the output of echo as an input? and how can I get it to work?

Answer 1

To ssh to a host, you use:
ssh 10.122.22.22
If you want to ssh to a host in a variable, you therefore use:
ssh "$devcluster2"
Meanwhile, echo text | command is like running command and then typing in "text". If you to run ssh by itself and wait for an opportunity to enter text, it fails just like it does in your script:
$ ssh
usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]
[-D [bind_address:]port] [-E log_file] [-e escape_char]
[-F configfile] [-I pkcs11] [-i identity_file]
...