expect

Handle multiple spawned processes in Expect script


Here is my use case for expect script ( one of few i have)

I want to run multiple sed command over ssh. Its like pre-build environment setup. I want to run something like this :-

#!/usr/bin/expect
set timeout -1

spawn -noecho bash -c "ssh -t user@host 'sed -i <some_stuff1> <file1>'"
spawn -noecho bash -c "ssh -t user@host 'sed -i <some_stuff2> <file2>'"
spawn -noecho bash -c "ssh -t user@host 'sed -i <some_stuff3> <file3>'"

expect {
  -re ".*sword.*" {
     exp_send "$env(PASS_WORD)\n"
     exp_continue
  }
}

But only last sed command will execute. 1st and 2nd will be skipped.

What could be the hidden gem i am missing?

Here is what i looked at so far but not helpful


Solution

  • You don't really need multiple (means parallel) spawn here.

    #!/usr/bin/expect
    
    set timeout 60
    
    set cmds [list "ssh host1 ..." "ssh host2 ..." "ssh host3 ..."]
    
    foreach cmd $cmds {
        spawn -noecho bash -c $cmd
        expect {
            -nocase "password" {
                exp_send "$env(PASS_WORD)\r"
                exp_continue
            }
            eof { wait } ; # at this time the last spawn'ed process has exited
        }
    }