What does spawn ,expect and send command in linux/unix

Question

The following three lines having three commands(spawn,expect,send), but what it does actually. Please explain any one

spawn ssh -oStrictHostKeyChecking=no -oCheckHostIP=no usr@$myhost.example.com'<br>
expect "password"<br>
send "$PWD\n" <br>
EOD

Solution

It is part of an expect script:

spawn opens a new process

expect waits for the previous spawned process to output the "expected" string (password in this case)

send writes to the spawned process stdin

EOD has no meaning in expect, perhaps it is part of another script?

Comments

[Jason Lee]

I think the pasted code snippet should have another EOD prior to it. Here it simply indicates the end of the here doc.