Implementation of a persistent shell #1
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TODO: There should really be a method to gracefully shut down the shell process. |
| let shellFile = "/bin/sh"; | ||
| if (process.platform === "win32") { | ||
| shellFile = process.env.comspec || "cmd.exe"; | ||
| } else if (process.platform === "android") { |
| }); | ||
| } | ||
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| createShellProcess(shell?: string) { |
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oh wait it's used further down. think the code could be slightly clearer (and not go through the process.platform checks if that work's going to be ignored anyway)
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This turned out to be harder to do than I thought and the solution here feels a tad hacky, but overall not too bad.
Because we want to run the commands in a persistent shell, and shells are for humans to write prompts in, it's actually not super easy to know when the last executed command has finished. We create a shell process by spawing
shand then all the 'real' commands are done by writing to stdin and reading from stdout/stderr (just like if you're using a terminal to work with a shell). In a tty, you get a prompt printed when the last command has finished executing, but this doesn't happen when runningshnot in a tty (such as spawing a child process from node.js).To work around it, we create a unique id for each command, and then
echothat id to stdout after the main command. We can listen on stdout and receive the real command's output, and when we see that unique id (which should never accidentally appear in the real output), we know to stop reading and return everything else to the caller.In addition to this, we use
echo $?to retrieve the exit code of the main command. There's a bit of string manipulation to get all the relevant output back out of the stdout stream.