rexpect interact(), giving control back to the user #30

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1. chama-chomo commented on Nov 1, 2020

   

   chama-chomo

   on Nov 1, 2020

   Last edited by chama-chomo

   Author

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   as a Rust newbie I was able to create kind of a POC for my ssh repl, my only problem is it doesn't feel very much like a standard ssh session with command/path expansion and so. There is definitely a better way. Nevertheless, I'm going to provide my piece of code for someone like me, as inspiration (this is my specific case ofc, not too much generic)..

   ...
       fn connect_ssh(&self, dest: Option<&String>) -> Result<()> {
           ConnectAction::do_ssh_repl(&dest.unwrap())
               .unwrap_or_else(|e| panic!("ssh session failed with {}", e));
           Ok(())
       }
   
       fn do_ssh_repl(host: &String) -> Result<()> {
           let mut ssh = ConnectAction::create_ssh_session(&host)?;
           ssh.exp_regex("\r\n.*root.*:~# ")?;
           ConnectAction::interact(&mut ssh)?;
           ssh.exp_eof()?;
           Ok(())
       }
   
       fn create_ssh_session(host: &String) -> Result<PtyReplSession> {
           println!("Connecting to host {}", host);
           let custom_prompt = format!("root@{}'s password: ", host);
           let custom_command = format!("ssh root@{}", host);
           let mut ssh = PtyReplSession {
               echo_on: false,
               prompt: custom_prompt,
               pty_session: spawn(&*custom_command.into_boxed_str(), Some(5000))?,
               quit_command: Some("Q".to_string()),
           };
           ssh.wait_for_prompt()?;
           ssh.send_line("root")?;
           Ok(ssh)
       }
   
       fn interact(session: &mut PtyReplSession) -> Result<()> {
           while let Some(WaitStatus::StillAlive) = session.process.status() {
               let mut user_input = String::new();
               print!("ssh session :> ");
               io::stdout().flush().expect("couldn't flush buffer");
               io::stdin().read_line(&mut user_input).expect("error: unable to read user input");
               session.writer.write(&user_input.into_bytes()).expect("could not write");
   
               let re = Regex::new(r".*root@.*:~# ").unwrap();
               let (before, _) = session.reader.read_until(&rexpect::ReadUntil::Regex(re)).unwrap();
   
               println!("{}", before);
           };
           Ok(())
       }
   

   👍React with 👍2Reacted by alienzj and flystary
2. BarretRen commented on Nov 21, 2022

   

   BarretRen

   on Nov 21, 2022

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   @chama-chomo, your workaround looks good, but it's still not perfect.
   For example, if I start gdb task with rexpect, i want a real gdb tty after calling interact. But in this way, it can't offer me that.
   This issue is opened two years before, but no updates for it. I will use pexpect for my tools.
   Life is short, I use python.^v^
3. wolfv commented on Aug 30, 2023

   

   wolfv

   on Aug 30, 2023

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   We've implemented an interact functionality in the pixi package manager (to spawn an interactive shell where we can source some scripts after the shell has started, and then give control to the user).

   You can have a look at the code here: https://github.com/prefix-dev/pixi/pull/316/files

   There were some changes:

   • set terminal to raw mode
   • enable ECHO for the terminal (to see what user types) - this is always deactivated in rexpect
   • be able to set the window size when the SIGWINCH signal happens
   • use select on the two filestreams (stdin of the parent and stdout of the child) to forward the input / output

   We've gone through a few iterations with this code and are reasonably happy with it now. I am not sure what the appetite is for these changes in rexpect. They are a bit deeper (especially with the ECHO part), but we could potentially make a PR to contribute the feature.

   👍React with 👍1Reacted by Peter Kuchar
4. epage

   added a commit that references this issue on Jan 27, 2026

   chore(deps): Update Rust Stable to v1.90 (rust-cli#30)

   ...

   676066a