10-09-2008
Which UNIX? Which FileSystem? Often the answer is: variable.
9 More Discussions You Might Find Interesting
1. Programming
Hi...
I am trying to read a binary data that have different types of messages of different lengths. I am using fread() but this functions needs the size and count to read the buffer from the file. I think this may cause that the buffer overlaps other messages.
Is there an alternative to read... (1 Reply)
Discussion started by: jlrodz
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2. AIX
Hi:-
One of our users is getting an error: "There is no process to read data written to a pipe.”
I am trying to find out what the pipe buffer size is currently set to. How do I go about this?
Thanks, (0 Replies)
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3. Red Hat
hi everyone,
can any one help change the buffer cache size in redhat and suse?? this error i got when i installed oracle 10g and it went well and when i try to mount the database using startup cmd it says too many buffer cache parameters (error code : ora-1034)
thnq in advance (0 Replies)
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4. Programming
When fread is used twice, the second time it seems to overwrite the first time's output. Is there any way to clear fread's internal buffer after each use ?
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Hi everybody,
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6. UNIX for Dummies Questions & Answers
Hi,
I am using the below command to get the output in a file called "Logs.txt"
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7. Programming
Hi,
Can I find size of the file from size of the buffer written?
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Thank You :) (1 Reply)
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Hello,
in one default UFS filesystem we have 8K block size (bsize) and 1K fragmentsize (fsize). At this scenary I thought all "FileSytem IO" will be 8K (or greater) but never smaller than the fragment size (1K). If a UFS fragment/blocksize is allwasy several ADJACENTS sectors on disk (in a ... (4 Replies)
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9. Red Hat
Hello guys,
I would like to ask you kindly if you don't know some quick and safe method how to shrink ext4 filesystem and reduce the size of a Logical Volume in Linux, please?
Thank you very much. (2 Replies)
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RRDp(3) User Contributed Perl Documentation RRDp(3)
NAME
RRDp - Attach RRDtool from within a perl script via a set of pipes;
SYNOPSIS
use RRDp
RRDp::start path to RRDtool executable
RRDp::cmd rrdtool commandline
$answer = RRD::read
$status = RRD::end
$RRDp::user, $RRDp::sys, $RRDp::real, $RRDp::error_mode, $RRDp::error
DESCRIPTION
With this module you can safely communicate with the RRDtool.
After every RRDp::cmd you have to issue an RRDp::read command to get RRDtools answer to your command. The answer is returned as a pointer,
in order to speed things up. If the last command did not return any data, RRDp::read will return an undefined variable.
If you import the PERFORMANCE variables into your namespace, you can access RRDtool's internal performance measurements.
use RRDp
Load the RRDp::pipe module.
RRDp::start path to RRDtool executable
start RRDtool. The argument must be the path to the RRDtool executable
RRDp::cmd rrdtool commandline
pass commands on to RRDtool. Check the RRDtool documentation for more info on the RRDtool commands.
Note: Due to design limitations, RRDp::cmd does not support the "graph -" command - use "graphv -" instead.
$answer = RRDp::read
read RRDtool's response to your command. Note that the $answer variable will only contain a pointer to the returned data. The
reason for this is, that RRDtool can potentially return quite excessive amounts of data and we don't want to copy this around in
memory. So when you want to access the contents of $answer you have to use $$answer which dereferences the variable.
$status = RRDp::end
terminates RRDtool and returns RRDtool's status ...
$RRDp::user, $RRDp::sys, $RRDp::real
these variables will contain totals of the user time, system time and real time as seen by RRDtool. User time is the time RRDtool
is running, System time is the time spend in system calls and real time is the total time RRDtool has been running.
The difference between user + system and real is the time spent waiting for things like the hard disk and new input from the Perl
script.
$RRDp::error_mode and $RRDp::error
If you set the variable $RRDp::error_mode to the value 'catch' before you run RRDp::read a potential ERROR message will not cause
the program to abort but will be returned in this variable. If no error occurs the variable will be empty.
$RRDp::error_mode = 'catch';
RRDp::cmd qw(info file.rrd);
print $RRDp::error if $RRDp::error;
EXAMPLE
use RRDp;
RRDp::start "/usr/local/bin/rrdtool";
RRDp::cmd qw(create demo.rrd --step 100
DS:in:GAUGE:100:U:U
RRA:AVERAGE:0.5:1:10);
$answer = RRDp::read;
print $$answer;
($usertime,$systemtime,$realtime) = ($RRDp::user,$RRDp::sys,$RRDp::real);
SEE ALSO
For more information on how to use RRDtool, check the manpages.
AUTHOR
Tobias Oetiker <tobi@oetiker.ch>
perl v5.16.3 2014-06-10 RRDp(3)