Executing an if statement after a specific output in expect script

Question

Is there a way to execute an if statement if I see a specific output? For example, when the console says "bad interpreter permission denied" I want to execute a command like "dos2unix file_name"?

So the logic will be like the following,

if (output is "bad interpreter permission denied")
{
  send dos2unix file_name
}
fi

This is an expect script.

Edit:

Could I do something like this in an expect script?

if (grep -cim1 '^M$' lruload.sh) -eq 1; then
send dos2unix filename
fi

Answer 1

When you say execute the commands, I hope you meant to execute the command in the shell. You can use exec command for this purpose.

I'm not sure where you are interacting. I mean like telnet or ftp or bash. Anyway, under any case, you will be sending a command and expecting a prompt.

send "command 1"
expect "prompt"
send "command 2"
expect {
    timeout { puts "timeout happened"}

    "bad interpreter per mission denied" {
         set result [exec dos2unix <filename>]
     }
}
# if need to intact with three application, further use 'send' and 'expect'

You have the result variable to store the dos2unix output.