Rohan Kishibe Rohan Kishibe - 1 month ago 5
Bash Question

how to use shell variable in expect session?

I try so send some files toward multiple servers using

scp
in bash script.
But I encountering problem.

here is the shell script I wrote.

#!/bin/sh

IP_LIST=('127.0.0.x' '127.0.0.y' '127.0.0.z')

for ip_addr in "${IP_LIST[@]}"
do
echo "$ip_addr"
expect << 'EOS'
set timeout 10
spawn scp -p /home/foo/bar/baz.txt user@"$ip_addr":/home/destdir
expect "*password*"
send "pasword\r"
expect eos
exit 0
EOS
done


I assume each element in
ip_addr
is assigned to the variable
ip_addr
,
but in
expect
session, element in the list doesn't assigned.

When I execute this script, such error message appear.

can't read "ip_addr": no such variable
while executing
"spawn scp -p /home/foo/bar/baz.txt user@"$ip_addr":/home/destdir"


It works when use
echo
command(displays each element in
IP_LIST
).

anybody know some good idea?

Answer

For shell's << STRING syntax, if STRING is quoted then it'll not expand variables so your $ip_addr is still $ip_addr to the Expect script but it's not defined in Expect. You can pass the ip_addr from shell to Expect with the env var. E.g.:

#!/bin/sh

IP_LIST=('127.0.0.x' '127.0.0.y' '127.0.0.z')

for ip_addr in "${IP_LIST[@]}"
do
    echo "$ip_addr"
    ip_addr=$ip_addr expect << 'EOS'
      set timeout 10
      spawn scp -p /home/foo/bar/baz.txt user@$::env(ip_addr):/home/destdir
      expect "*password*"
      send "pasword\r"
      expect eos; # do you mean `eof'?
      exit 0
EOS
done