Using read to prompt for editable user input in Bash 3 Post: 302737119

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Top Forums Shell Programming and Scripting Using read to prompt for editable user input in Bash 3 Post 302737119 by Corona688 on Wednesday 28th of November 2012 11:33:47 AM

11-28-2012

Registered User

Hitting enter for the default value is what I tend to see done in these situations.

The other way, beyond bringing an external utility with you, would be to play funny games with the terminal device and handle all keystrokes by yourself:

Code:

#!/bin/bash

oldsettings=$(stty -g)

trap "stty $oldsettings" EXIT

readdefault() { # variable prompt default
        local POS="${#3}"
        local VALUE="$3"
        local C

        stty -icanon min 1 time 0 -icrnl -echo

        printf "%s" "$2$3"

        while true
        do
                C="$(dd bs=10 count=1 2> /dev/null)"

                [ -z "$C" ] && continue

                # Okay, you've got raw keystrokes.  Now you're on your own.
        done

        stty icanon
}

readdefault VAR "Enter something:" "qwerty"

I tried filling out more, but could not for the life of me get my terminal and tput to agree on what the 'backspace' key is, even though backspace works in my terminal.

Example partly from here.

You can see why what you're asking for really isn't trivial. It may be more straightforward to upgrade your shell.

Last edited by Corona688; 11-28-2012 at 01:54 PM..

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LEARN ABOUT NETBSD

stty

STTY(3) 						   BSD Library Functions Manual 						   STTY(3)

NAME

     stty, gtty -- set and get terminal state (defunct)

LIBRARY

     Compatibility Library (libcompat, -lcompat)

SYNOPSIS

     #include <sgtty.h>

     stty(int fd, struct sgttyb *buf);

     gtty(int fd, struct sgttyb *buf);

DESCRIPTION

     These interfaces are obsoleted by ioctl(2).  They are available from the compatibility library, libcompat.

     The stty() function sets the state of the terminal associated with fd.  The gtty() function retrieves the state of the terminal associated
     with fd.  To set the state of a terminal the call must have write permission.

     The stty() call is actually 'ioctl(fd, TIOCSETP, buf)', while the gtty() call is 'ioctl(fd, TIOCGETP, buf)'.  See ioctl(2) and tty(4) for an
     explanation.

DIAGNOSTICS

     If the call is successful 0 is returned, otherwise -1 is returned and the global variable errno contains the reason for the failure.

SEE ALSO

     ioctl(2), tty(4)

HISTORY

     The stty() and gtty() functions appeared in 4.2BSD.

BSD
								   June 4, 1993 							       BSD

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