Problem reading terminal response string from Zsh Post: 303010561

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Top Forums Shell Programming and Scripting Problem reading terminal response string from Zsh Post 303010561 by rovf on Wednesday 3rd of January 2018 07:33:00 AM

01-03-2018

Registered User

Problem reading terminal response string from Zsh

Note: This posting is related to my posting at bash - Reading answer to control string sent to xterm - Stack Overflow , but I could get there a solution only for bash. I can use that solution, but for curiosity, I wonder, whether I could do this in Zsh as well.

The problem is to send a (Posix-) terminal query string to the terminal where the (interactive) shell is running, and to read the response from the terminal. For example, when we send Escape followed by the letter Z, the terminal is supposed to respond with the terminal ID. This response also starts with an Escape, followed by an arbitrary number of characters. Since I don't know the number of characters returned in advance, I have to accumulate them one by one.

This is the solution I achieved with bash, ask_tty.sh:

Code:

#!/bin/bash

str='' # Buffer for response
tty=$(tty)

# Send query string to terminal. Example: Esc Z queries for terminal id
echo -e '\e'${1:-Z}  >$tty

# Read response from terminal
while :
do
  read -rs -t 1 -n 1 <$tty
  if [[ -z $REPLY ]]
  then
    break
  fi
  str="${str}$REPLY"
done

# Output response without leading Esc
echo "${str#?}"

If I run in my terminal either ask_tty.sh Z or ask_tty.sh (because I made Z the default value), I get as response on stdout

[?63;1;2;4;6;9;15;22;29c

The actual reading of each character is done by read -rs -t 1 -n 1 <$tty.

I feel that for adapting this solution to Zsh, I have to change the bash read to an equivalent Zsh read, but I could not get it done: Either the command hangs, or it returns only the first character of the answer string. For instance, I tried read -rs -t -k and read -rs -t 1 -k 1.

How can I solve this in Zsh?

Update: I'm using Zsh 5.3 (given the evolution of Zsh, version might matter here), running on Cygwin.

Last edited by rovf; 01-03-2018 at 09:46 AM.. Reason: Providing additional information

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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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