[SOLVED] simple to some 3 hours wasted for me question

gary_in_springhill · 03-17-2010, 04:23 PM

Code:

bba = (os.system("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\s.*//' "))
	bbb = (os.system("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\S*\s*//' "))
	
	print bbb

568
398
0

I can't figure why this prints the returned correct bba and bbb values even when I don't ask it to and when I issue the print bbb it gives a zero. I'm trying to plug in these values into Qcanvas resize command and it's taking the 0, 0 instead of the correct returned values.

c.resize(bba, bbb)

gary_in_springhill · 03-17-2010, 04:26 PM

running pyqt3

Sergei Steshenko · 03-17-2010, 04:29 PM

Quote:

Originally Posted by gary_in_springhill

Code:

bba = (os.system("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\s.*//' "))
	bbb = (os.system("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\S*\s*//' "))
	
	print bbb

568
398
0

I can't figure why this prints the returned correct bba and bbb values even when I don't ask it to and when I issue the print bbb it gives a zero. I'm trying to plug in these values into Qcanvas resize command and it's taking the 0, 0 instead of the correct returned values.

c.resize(bba, bbb)

If you run the command lines outside the Python script, do they print the lines ?

If they do, why do you think the lines shouldn't be printed from your Python script ?

rweaver · 03-17-2010, 04:35 PM

Because the return value isn't what they're outputting to the screen, it's the return value from the execution of the commands in the shell (eg: 0 is normal termination). If you want to actually grab stdout I think you need to do something more like this:

Code:

bba = Popen("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\s.*//' ", stdout=PIPE, shell=True).stdout.read()
bba = Popen("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\S*\s*//' ", stdout=PIPE, shell=True).stdout.read()

You might have to do some escaping to get this to work and I think popen is part of subprocess. YMMV... Python isn't my language of choice

Edit: What's currently happening is this
system call -> grep %%BoundingBox: ~/hpgl-hot-folder/*.job | sed 's/%%BoundingBox: 0 0 //' | sed 's/\s.*//'
Output to STDOUT: 568
Return: 0
Set bba = Return Value

system call -> grep %%BoundingBox: ~/hpgl-hot-folder/*.job | sed 's/%%BoundingBox: 0 0 //' | sed 's/\S*\s*//'
Output to STDOUT: 398
Return: 0
Set bbb = Return Value

print bbb -> outputs 0 (because that is what bbb got set to)

Basically you need to set your variable to the stdout and not the return value.

Here, check this out: http://docs.python.org/library/subpr...ule-subprocess

gary_in_springhill · 03-17-2010, 04:41 PM

Thanks so much it made other errors make sense now also.

Again thanks so much

gary_in_springhill · 03-17-2010, 05:42 PM

Works great after conv. to int

Thanks so much

rweaver · 03-18-2010, 10:22 AM

So what was the final code you ended up using out of curiosity (it might help someone else with the same problem in the future)?

gary_in_springhill · 03-19-2010, 01:35 PM

I should have auto posted the solution:

Code:

bba = subprocess.Popen("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\s.*//' ", stdout=PIPE, shell=True).stdout.read()
	bbb = subprocess.Popen("grep %%BoundingBox:   ~/hpgl-hot-folder/*.job | sed  's/%%BoundingBox: 0 0 //' | sed 's/\S*\s*//' ", stdout=PIPE, shell=True).stdout.read()
	bba = int(bba)
	bbb = int(bbb)
	c = qtcanvas.QCanvas(self) # <- gives the canvas a parent QObject
	c.resize(bba, bbb)