Controlling user input Post: 303038255

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Top Forums Shell Programming and Scripting Controlling user input Post 303038255 by Don Cragun on Thursday 29th of August 2019 12:07:31 AM

08-29-2019

Registered User

Quote:

Originally Posted by Chubler_XL

Since you specify using bash shell we can flush the input buffer using:

Code:

while read -rs -N 1 -t 0.1 2> /dev/null ; do : ; done

so your script would look like this:

Code:

#!/bin/bash

for i in 1 2 3; do
 echo "Ready?"
 sleep 2
 mpg123 $i.mp3
 echo "Ok now you can respond. Press 1 if you liked it, 2 if you didn't."
 while read -rs -N 1 -t 0.1 2> /dev/null ; do : ; done
 read -n 1 RESPONSE
done

Hi Chubler_XL,
That might work with some versions of bash, but it won't work with 3.2.57 (which comes with the most recent release of macOS Mojave) since the read built-in in that version doesn't have a -N option. The loop you suggest above silently throws away the diagnostic saying there is no -N option and gives no indication that whatever was intended to be done by the while loop didn't do anything. The following read then reads the next available character no matter when it was typed.

Since darwin_866 has told us neither what OS is being used nor which version of bash is being used, we don't have any way to know if what you suggested might work in his/her environment.

Cheers,
Don

Don Cragun

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libbash

LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME

     libbash -- A bash shared libraries package.

DESCRIPTION

     libbash  is  a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
     want to load and use in scripts of your own.

     It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.

     Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1).  A bash shared library that can be  loaded
     using
     ldbash(1) must answer 4 requirments:

     1.     It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).

     2.     It must contain a line that begins with '#EXPORT='.  That line will contain (after the '=') a list of functions that the library
	    exports.  I.e. all the function that will be usable after loading that library will be listed in that line.

     3.     It must contain a line that begins with '#REQUIRE='.  That line will contain (after the '=') a list of bash libraries that are
	    required for our library.  I.e. every bash library that is in use in our bash library must be listed there.

     4.     The library must be listed (For more information, see ldbashconfig(8)).

   Basic guidelines for writing library of your own:
     1.     Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.

     2.     Try to declare all variables intended for internal use as local.

     3.     Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
		  __<library_name>_
	    For example, internal function myfoosort of hashstash library should be named as
		  __hashstash_myfoosort
	    This helps to avoid conflicts in global name space when using libraries that come from different vendors.

     4.     See html manual for full version of this guide.

AUTHORS

     Hai Zaar <haizaar@haizaar.com>
     Gil Ran <ril@ran4.net>

SEE ALSO

     ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1)

Linux								       Epoch								     Linux

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