Both these assumptions do not stand up to benchmark testing except perhaps on the first use of "cat" after a clean boot.
Don't be ridiculous.
...and this is on a dual-core system. If grep had to time-share with cat, the performance would be worse yet. There is of course a cost in resources and time to launching a process and piping data through it, especially for small amounts of data. It's only insignificant when you do it once.
Last edited by Corona688; 09-15-2010 at 02:58 PM..
hi everybody,
how do i open a txt file writen in unix on to a web page
so when i want to view the txt file that was generated from a shell program, that file is open on a web page
do i use the cat > filename.html command to do this, or is there another way
many thanks
:D (2 Replies)
I would like to append some statement into 1 single file so that it can be concatenate together in 1 word. I have tried >> but it will seperate my 2 statement into 2 rows.
# cat abc.txt cde.txt > result.txt
where abc.txt is "abcde" and cde.txt is "12345"
the result should come out as... (3 Replies)
Dear All
I have two text files File1.txt and File2.txt . I am concatenating the two files and making it as single file Cat_File.txt. Now i need to keep joined file in two different path. that is I need to use cat command only once ,but store joined file in two different locations. Since... (3 Replies)
Hello,
So I sorted my file as I was supposed to:
sort -n -r -k 2 -k 1 file1 | uniq > file2
and when I wrote
> cat file2
in the command line, I got what I was expecting, but in the script itself
...
sort -n -r -k 2 -k 1 averages | uniq > temp
cat file2
It wrote a whole... (21 Replies)
I believe I used the cat command to append a file beside another file (instead of below it) but I did not document it any where and I can't remember exactly how I did it. Has anyone else done this? I have tried all the cat options individually with no luck. It may be a combination of options.
... (2 Replies)
I want to concatenate 100 files to one file and append file name in each record to find out which file it came from
for a in $(<shal_group)
do
cat $a >> bigoutput.group
The above code put all files in one file but i want file name appended to each file
Record should be like this... (3 Replies)
I have a file "sample.txt" with the content as below:
Hi
This is a Sample Text.
I need a single command using cat which serve the following purpose.
1.display the contents of sample.txt
2.append some text to it
3. and then exit
But, all should be served by a sinle... (1 Reply)
Discussion started by: ashok.g
1 Replies
LEARN ABOUT SUSE
rrdp
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 v5.12.1 2010-03-22 RRDp(3)