当对期望脚本进行子流程调用时，Python避免使用花括号

Question

I have the following expect script named autossh.exp

#!/usr/bin/expect -f
set user [lrange $argv 0 0] 
set password [lrange $argv 1 1] 
set ipaddr [lrange $argv 2 2]
set command [lrange $argv 3 3]
set timeout 10
# now connect to remote UNIX box (ipaddr) with given script to execute
spawn ssh -o StrictHostKeyChecking=no $user@$ipaddr 'bash -s' < $command
expect "*?assword:*"
# Send password aka $password
send -- "$password\r"
interact
# send blank line (\r) to make sure we get back to gui
#send -- "\r"

I am calling this expect script from a python file which is like below

import subprocess
user = "abc"
operation = "l"
password = "xyz"
brokerip = "10.XX.XX.XXX"
command = ' topics.sh '+operation+' '+user
subprocess.call(['autossh.exp', user, password, brokerip, command])

I want to pass the topics.sh (which is locally) found to ssh.

When i run the python file i get the below error.

spawn ssh -o StrictHostKeyChecking=no abc@10.xx.xx.xxx 'bash -s' < { topics.sh l abc}
tmhaskar@xx.xx.xx.xxx's password: 
bash: {: No such file or directory

Can some one tell me is there any work around to avoid the curly braces.

Thanks in advance.

Answer 1

Try using lindex rather than lrange . lrange attempts to return a well formed list, so if it finds certain characters in the data it will add braces or backslashes to guarantee you get a valid list even if it's a list with a single element. lindex, on the other hand, returns a single element from a list.

% set argv [list abc xyz 10.xx.xx.xxx "topics.sh 1 abc"]
abc xyz 10.xx.xx.xxx {topics.sh 1 abc}
% lrange $argv 3 3
{topics.sh 1 abc}
% lindex $argv 3
topics.sh 1 abc