How to make "echo"ed line editable in an interactive shell script?

I have the following problem: in an interactive script, when asking for input, I want to display a suggestion and make it editable. It is a similar functionality to "arrow up and edit the last command" in a command prompt, except without the "arrow up". I tried several different things but no success so far.

These are the things I tried:

1) Get input from editor, like so:

echo "$SUGGESTION\c"
INPUT=`ed -` # problem with this approach is that 'ed' starts in command mode 
             # by default, and I would need input mode

2) Use read -e

echo "$SUGGESTION\c"
read -e INPUT # doesn't work as advertised

After extensive Googling I am convinced that the 2) should work, but it doesn't. First of all, I cannot delete the $SUGGESTION without typing some input first; after some characters are typed, backspace deletes the whole line, not just one character.

So my question is: how to make "read -e" work or is there another approach to s开发者_开发百科olve this? Your help is very much appreciated!

It does work as advertised, but you need an extra parameter to do what you want:

read -e -i "$SUGGESTION" INPUT

Unfortunately, that's only available in Bash 4.

If you have a C compiler and readline available, here's a quick hack that you could use. Save the following to myread.c (or whatever) and compile it (you'll need to link with readline). For GCC, that would be: gcc -o myread myread.c -lreadline.

#include <stdio.h>
#include <readline/readline.h>

int main(int argc, char **argv)
{
    if (argc != 2)
        return 1;

    // stuff the input buffer with the default value
    char *def = argv[1];
    while (*def) {
        rl_stuff_char(*def);
        def++;
    }

    // let the user edit
    char *input = readline(0);
    if (!input)
        return 1;
    // write out the result to standard error
    fprintf(stderr, "%s", input);
    return 0;
}

You can use it like this:

myread "$SUGGESTION" 2> some_temp_file
if [ $? -eq 0 ] ; then 
  # some_temp_file contains the edited value
fi

Lots of room for improvement, but I guess it's a start.