Op 19 mei 2010, om 03:37 heeft Greg Guerin het volgende geschreven:
> appledev wrote:
>
>> arguments = [NSArray arrayWithObjects: @"-c", @"/bin/df -k| /usr/bin/grep
>> /dev/ | /usr/bin/awk '{print $1 $4 $5 $6;}'",nil];
>
>
> Your awk syntax is somewhere between quirky and wrong. Since you didn't
> mention what the problem was, I will assume the output you want is not the
> output you're getting.
It was just a sample to avoid the tabs \t
>
> I will also assume that you ARE getting some output, despite Alastair
> Houghton previously noted comment that waiting for termination before reading
> stdout can be unsafe. Unless you have a whole lot of mounted disks, the pipe
> buffer won't fill up and cause deadlock (it's about 16 KB, empirically
> determined, in all Mac OS X versions I've tested, since 10.0).
I know it is very small just a few hundred bytes, but it is still good to know.
> If you want the default output field separator, you need this awk line:
> print $1, $4, $5, $6
>
> The default output field separator is defined by the awk variable named OFS.
> To use tab as OFS:
> { OFS="\t"; print $1, $4, $5, $6;}
>
> You can discover all this simply by reading awk's man page.
> simply??
Now you ask to much. ;-) In fact I did read the page, but just overlooked that
OutputFieldSep. Mainly because my script did work in the terminal and was
focused on where is my output.
>
> The resulting bash command-line is:
> /bin/df -k| /usr/bin/grep /dev/ | \
> /usr/bin/awk '{ OFS="\t"; print $1, $4, $5, $6;}'
>
> I have inserted a \ to force a continuation line, so mail doesn't line-fold
> badly.
>
> To encode that properly as an Objective-C string literal, you need to escape
> both the double-quotes and the backslash:
> arguments = [NSArray arrayWithObjects:
> @"-c",
> @"/bin/df -k| /usr/bin/grep /dev/ | /usr/bin/awk '{ OFS=\"\\t\"; print $1,
> $4, $5, $6;}'",
> nil];
Yes I got that and will save it, thanks. Btw, yes I believe that awk can filter
/dev/, but this was the shortest that I could come with.
>
> (The Objective-C was written in mail and not compiled. The command-line with
> the modified awk code was tested in bash.)
>
> And I should note that awk is perfectly capable of matching the "/dev/"
> pattern by itself with no assistance from grep. This is left as an exercise
> for the interested reader.
Because I didn't see any result, I noticed that this happened only when I use
/bin/sh -c.
My code was just a short piece in main as test bed, and did trust my NSLog
output which was ok and visible in the xcode console when NOT using /bin/sh.
Because yesterday it was an early and long day, I did figure out this morning
that when using /bin/sh NSLog is redirected to the system console and not
visible in xcode console anymore.
Now my code is alive and kicking, how can I get NSLog back into the Xcode
console, because all my later NSLogs are not visible in xcode. How do I reset
the stnd output? Should I, somewhere, call or send exit?
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