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spawn, expect and send commands in Linux

Apr 10, 2022 · 1 min read · Post a comment
spawn, expect and send commands in Linux

spawn, expect and send commands are usually part of a SSH bash scripts. So, I’m gonna briefly explain them, starting with expect since the rest of them are part of it.

Prerequisites

  • Linux shell environment

Example

spawn ssh -o \"StrictHostKeyChecking=no\" \"${USER}@myhost.example.com\"
expect \"${USER}'s password:\"
send \"${PASSWORD}\n\"

Solution

expect is a scripting utility that communicate with interactive scripts.

spawn starts a new process. For instance initiating ssh session as in the example above.

send writes to the spawned process standard input (std). It has a file descriptor value of 0.

Conclusion

Official expect documentation.
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