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autorespond(1) -- Terminal Command Auto-Responder

SYNOPSIS

autorespond [-h|--help] [-V|--version] [-t|--timeout-soft seconds] [-T|--timeout-hard seconds] [-r|--response input] command [argument ...]

DESCRIPTION

autorespond(1) is a small utility for executing a command in an interactive terminal session and automatically sending a response input to the command in case of an interaction timeout.

It is intended to be used in training scenarios where some interactive commands (like a shell) have to be executed in a scripted session but they should be automatically terminated (like sending "exit\n") in case the trainee does not manually interact with it. This allows the same scripting sessions to be executed in batch and interactively.

OPTIONS

The following command-line options and arguments exist:

  • [-h|--help]: Show usage information of autorespond(1).

  • [-V|--version]: Show version information of autorespond(1).

  • [-t|--timeout-soft seconds]: Time to wait in seconds before injecting the response on stdin, in case no interaction happened on stdin by the user at all.

  • [-T|--timeout-hard seconds]: Time to wait in seconds before injecting the response on stdin, after no or the last interaction happened on stdin by the user.

  • [-r|--response input]: Response message to inject on stdin instead of the user. In the input data, the following syntactical constructs are expanded:

    • \o{num}: create character by octal character code like \o{177}.
    • \d{num}: create character by decimal character code like \d{127}.
    • \x{num}: create character by hexadecimal character code like \x{7f}.
    • \r, \n, \t, \v: create linefeed, newline, tab and vertical tab characters through short-hand escape sequences.
    • \k{keystroke}: create character by logical keystroke. The keystroke argument can be either ctrl+X where X is a to z or it can be the special keys return/cr, linefeed/lf, backspace/bs and delete/del.

  • command: The command to execute. It can be either an absolute path or a program in $PATH.

  • [argument ...]: Zero or more arguments passed to the command.

HINT

If you need to evaluate shell constructs like pipelines or file descriptor redirections, use an intermediate shell as in autorespond [...] sh -c '[...]'.

EXAMPLES

# interrupt after 10 seconds after the last user interaction
$ autorespond -T 10 -r '\k{ctrl+c}\n' tail -f logfile

# terminate after 30 seconds in case of no user interaction at all
$ autorespond -t 30 -r 'exit\n' bash

HISTORY

The autorespond(1) utility was developed in June 2020 to allow batch execution of an otherwise interactive training session.

AUTHOR

Dr. Ralf S. Engelschall rse@engelschall.com