getting output from a program executed from c++

dfuse · 08-19-2003, 03:34 PM

Hey, when I try to determine the total size of a directory (in Qt, C++) with a recursive function, it takes a while for large directories. So I was wondering how I could use the 'du' command on the directory and parse the output of that command to a QString (without the user noticing it,i.e. not opening an extra xterm) I know this should be possible, I just don't know how. If anybody could set me in the right direction, I'd be very happy!

kev82 · 08-19-2003, 04:01 PM

you need to look up these functions, the first choice is superior

1) pipe(), fork(), dup2(), exec*()
OR
2) popen(), pclose()

i think youd be better with your recursive function though, for something simple like this its easier to write your own code.

btw - du will take just as long as your own function, it does the same thing.

dfuse · 08-20-2003, 05:39 AM

OK thanks for the help! I'll try it out. Are you sure du is as fast (slow) as a simple recursive function? It can take up to 2sec to determine the size of my mp3 dir, with du it is instantaneously. Maybe because in my function I have to make a new QFileInfo everytime to determine the filesize.

kev82 · 08-20-2003, 05:48 AM

oh, i thought you were using opendir and stat in your recursive function, i dont know how fast/slow the qt method is.

for grabbing the output of du check out www.advancedlinuxprogramming.com chapters 3 and 5.4, it explains the above mentioned functions.

UltimaGuy · 08-21-2003, 05:23 AM

Hei, kev82, that was a good link. Do you have any such links. If so, please post it.

kev82 · 08-21-2003, 08:18 AM

umm, what sort of links do you want, i have a bad habbit of not writing down or bookmarking links, i just remember where i found them.

UltimaGuy · 08-22-2003, 02:24 AM

Well, the sort of links that help in understanding and boosts us towards system programming in Linux. I prefer C++ over C, and if you have any links, I will thank you if you share it.