Dynamic / Changing shell text?

[Firewing1]

Hello,
I've seen many programs -- eg Yum, Fsck, RPM, etc that will output progress bars during their run. Although, it's dynamic text -- It's not like

1% [program returns, waits a few seconds, and outputs the new value]
7.6% [same thing]
15%

It's one line that changes to the new value. Any tips on how to make these?

And, for a bonus, does anyone know how to take their values and use them for a GUI like YumEx does? I know how PyGTK works, I just need how to retrieve these values. I've tried looking at it's source, but couldn't find it.
Firewing1

[RedFedora]

For the progress bar, you can use logic like this:

while (! done)
{
printf("You are %d percent done.", my_percent);
// do some stuff
printf("\r");
}

The "\r" returns the cursor to the start of the line. I think
there is a better way to do this with ncurses, but this
is the really simply way.


I suppose if you were piping the output of your command to a GUI program,
you could just search the line for the number abd use that in your progress
bar. See "man popen".

[brunson]

For text, you can just print an ascii CarriageReturn character to put yourself at the beginning of the line and write the line again (you have to supress the newline each time you output).

In a GUI standard operating procedure would be to start the subprocess with a popen() call, then use select() to wait for output on the file descriptor, read any changes when the they occur, then update the GUI accordingly. Simple in concept, only a little hairy in implementation.

[Firewing1]

Thanks!
Firewing1