How to pass argument in Expect through the command line in a shell script

Question

I am passing argument in Expect through the command line in a shell script.

I tried this

#!/usr/bin/expect -f
    
set arg1 [lindex $argv 0]
    
spawn lockdis -p
expect "password:" {send "$arg1\r"}
expect "password:" {send "$arg1\r"}
expect "$ "

But it's not working. How can I fix it?

Solution 1

If you want to read from arguments, you can achieve this simply by

set username [lindex $argv 0];
set password [lindex $argv 1];

And print it

send_user "$username $password"

That script will print

$ ./test.exp user1 pass1
user1 pass1

You can use Debug mode

$ ./test.exp -d user1 pass1

Solution 2

A better way might be this:

lassign $argv arg1 arg2 arg3

However, your method should work as well. Check that arg1 is retrieved. For example, with send_user "arg1: $arg1\n".

Solution 3

I like the answer provided with this guide.

It creates a parse argument process.

#process to parse command line arguments into OPTS array
proc parseargs {argc argv} {
    global OPTS
    foreach {key val} $argv {
        switch -exact -- $key {
            "-username"   { set OPTS(username)   $val }
            "-password"   { set OPTS(password)   $val }
        }
    }
}
parseargs $argc $argv
#print out parsed username and password arguments
puts -nonewline "username: $OPTS(username) password: $OPTS(password)"

The above is just a snippet. It's important to read through the guide in full and add sufficient user argument checks.

Solution 4

#!/usr/bin/expect
set username [lindex $argv 0]
set password [lindex $argv 1]
log_file -a "/tmp/expect.log"
set timeout 600
spawn /anyscript.sh
expect "username: " { send "$username\r" }
expect "password: " { send "$password\r" }
interact

View more solutions

Comments

[joebeeson]

While this works, be careful using it as your process will appear with the arguments, username and password, when doing something like "ps aux"

[Vivek]

can we loop the argument list and put them in array?

[Timo]

The expect script is missing

[eulerworks]

It isn’t, “missing” it works the same way for any expect script that would be called via bash. Though in this example it would need to be called, “exp.expect.” There was no need for a downvote, my answer explains how to handle what was in question.

[Timo]

ok, I expected the content of your script which references the parameters from outside as the others showed in their examples.

[spbnick]

The code above is for TCL which expect is using, and doesn't make sense for Bash.

[Sohail Si]

I like argument checking all the time

[Han Zhang]

That's why you should pass it a file where your username and password are kept privately.