Expect ssh script (execute command on remote machine)

Question

I'm writing an expect script that executes a command on a remote server using ssh.

Command syntax: ssh <classname> <command>

Code:

set ip "hive28.cs.berkeley.edu"
set class [lindex $argv 0]
// set $user and $ip according to class

set cmd [lindex $argv 1]
spawn ssh "$user\@$ip '$cmd'"
expect "assword"
send "$password\r";
interact

Unfortunately, I get this error:

~/foo> ssh2 162 'pwd'

spawn ssh ***@hive28.cs.berkeley.edu 'pwd'
ssh: Could not resolve hostname hive28.cs.berkeley.edu 'pwd': Name or service not known
send: spawn id exp6 not open
    while executing
"send "$password\r""
    invoked from within <...>

But when I run the generated command directly, it works (ignore the gdircolors warnings):

~/foo> ssh ***@hive28.cs.berkeley.edu 'pwd'
***@hive28.cs.berkeley.edu's password: 
/home/ff/cs162/adm/bashrc.d/70-gnu.sh: line 36: gdircolors: command not found
/home/cc/cs162/sp16/class/***

If you ssh-keygen and ssh-copy-id first, you don't need expect at all. — glenn jackman
– glenn jackman, Commented Jan 24, 2016 at 11:36

Will · Accepted Answer · 2016-01-24 11:38:18Z

1

Try this instead:

set ip "hive28.cs.berkeley.edu"
set class [lindex $argv 0]

set cmd [lindex $argv 1]
spawn ssh "$user@$ip" "$cmd"
expect "assword"
send "$password\r";
interact

The problem seems to be with your quoting. "$user\@$ip" and "$cmd" are two separate arguments.

edited Jan 24, 2016 at 11:38

answered Jan 24, 2016 at 4:56

Will

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3 Comments

glenn jackman Over a year ago

2 minor points about Tcl(expect): 1. @ is not a special character and does not need to be escaped; 2. Tcl does not require quotes around variables, even if the variable value contains whitespace.

Will Over a year ago

I'm fully aware; I was trying to make minimal changes to OP's script. Quotes are for clarity; they don't cause harm. But, good to point out in a comment! I'll remove the @ escape even though it was in the original code. Thanks!

Will Over a year ago

Awesome, glad to help :)

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