Export Bash command-line-argument variables for use in embedded Expect

Question

The echo test shows me my command line variables are working, but how do I pass them, export them, to be used in an embedded expect?

#!/bin/bash

echo name of script is $0
echo host is $1
echo hostusername is $2
echo hostpassword is $3

expect -c 'spawn ssh -l $2 $1 < ./sf-wall_scp_bash.sh
sleep 2

expect {
"(yes/no)? " {send "yes\n"}
    exp_continue
}

expect {
"?assword" {send "$3\r"}
}
sleep 1
'

If invoked with the expect shebang, it works like

#!/usr/bin/expect

set host [lindex $argv 0]
set hostusername [lindex $argv 1]
set hostpassword [lindex $argv 2]


spawn ssh -l $hostusername $host
sleep 2

expect {
"(yes/no)? " {send "yes\n"}
    exp_continue
}

expect {
"?assword" {send "$hostpassword\r"}
}
sleep 1

...which works as expected. I need to use bash though and embed expect because the script is needing to call bash specific commands, functions, built in variables...otherwise simply using the second example would be a working option, but it is not.

I've tried declaring and exporting the command line argument variables, and changing $1, $2, $3 in the first example above respectively to the variable names declared and exported, which works in another script I have in which I am actually declaring the variables within the script...the difference being they are not command line arguments.

host=$1
export host
hostusername=$2
export hostusername
hostpassword=$3
export hostpassword

as well as just exporting them

export host
export hostusername
export hostpassword

and attempting the first example above. No change, expect continues to claim

can't read "X": no such variable

In another bash script I was able to successfully export variables by BOTH declaring them and then exporting them as in the example above. But I have not been able to have any such luck with passing bash command line argument variables to expect

Answer 1

Code with nesting quotes is not easy to write and read. I recommend you use the shell's here-document syntax. For example (demo'ing 2 ways of passing bash vars to expect):

$ cat foo.sh
arg1=$1
export arg2=$2

expect << END
puts $arg1
puts \$env(arg2)
END
$ bash foo.sh hello world
hello
world
$

I prefer export var from the shell and reference it with $env(var) in expect as you'll not have to worry about if the var has some special chars (like ', " or spaces) in it.