CODEWITHSUNDEEP
linuxbashshellscripting
Naresh Mani
Naresh Mani

Reputation: 1

Respond Y dynamically to a shell program

We have a startup script for an application (Owned and developed by different team but deployments are managed by us), which will prompt Y/N to confirm starting post deployment. But the number of times it will prompt will vary, depends on changes in the release.

So the number of times it will prompt would vary from 1 to N (Might be even 100 or more than that).

We have automated the deployment and startup using Jenkins shell script jobs. But startup prompts number is hardcoded to 20 which might be more at sometime.

Could anyone please advise how number of prompts can be handled dynamically. We need to pass Y whenever there is pattern in the output "Do you really want to start".

Checked few options like expect, read. But not able to come up with a solution.

Thanks in advance!

Upvotes: 0

Views: 147

Answers (1)

bk2204
bk2204

Reputation: 76409

In general, the best way to handle this is by (a) using a standard process management system, such as your distro's preferred init system; or, if that's not possible, (b) to adjust the script to run noninteractively (e.g., with a --yes or --noninteractive option).

Barring that, assuming your script reads from standard input and not the TTY, you can use the standard program yes and pipe it into the command you're running, like so:

$ yes | ./deploy

yes prints y (or its argument) over and over until it's killed, usually by SIGPIPE.

If your process is reading from /dev/tty instead of standard input, and you really can't convince the other team to come to their senses and add an appropriate option, you'll need to use expect for this.

Upvotes: 1

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