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From: Janis Papanagnou on 11 Aug 2010 11:36
On 11/08/10 17:04, srikanth wrote:
> On Aug 11, 8:55 am, Barry Margolin <bar...(a)alum.mit.edu> wrote:
>> In article
>> <9a7c7480-8de2-4c39-9da9-15fd9b111...(a)i19g2000pro.googlegroups.com>,
>> srikanth <srikanth0...(a)gmail.com> wrote:
>>> On Aug 10, 10:30 pm, pk <p...(a)pk.invalid> wrote:
>>>> On Tue, 10 Aug 2010 08:06:47 -0700 (PDT) srikanth <srikanth0...(a)gmail.com>
>>>> wrote:
>>
>>>>> Hi All,
>>>>> Just wanted to know if we can generate data with given input size with
>>>>> the help of shell script. Any idea from our group?
[...]
>>> I Just want to generate files with data. Any type of data that doesn't
>>> depend upon the content what it is..
>>> How can we do this with the help of awk or perl?
>>
>> If you use /dev/random in the above command, you'll get the specified
>> amount of random bytes.
>>
>
> It should contain human readable data not he system readable data. If
> i use dd if=/dev/random it is generation some system level data which
> we can't read.

Certainly it is human readable if you pipe it, e.g., through od(1).

Janis
From: John Kelly on 11 Aug 2010 11:46
On Wed, 11 Aug 2010 17:36:56 +0200, Janis Papanagnou
<janis_papanagnou(a)hotmail.com> wrote:

>On 11/08/10 17:04, srikanth wrote:
>> On Aug 11, 8:55 am, Barry Margolin <bar...(a)alum.mit.edu> wrote:
>>> In article
>>> <9a7c7480-8de2-4c39-9da9-15fd9b111...(a)i19g2000pro.googlegroups.com>,
>>> srikanth <srikanth0...(a)gmail.com> wrote:
>>>> On Aug 10, 10:30 pm, pk <p...(a)pk.invalid> wrote:
>>>>> On Tue, 10 Aug 2010 08:06:47 -0700 (PDT) srikanth <srikanth0...(a)gmail.com>
>>>>> wrote:
>>>
>>>>>> Hi All,
>>>>>> Just wanted to know if we can generate data with given input size with
>>>>>> the help of shell script. Any idea from our group?
>[...]
>>>> I Just want to generate files with data. Any type of data that doesn't
>>>> depend upon the content what it is..
>>>> How can we do this with the help of awk or perl?
>>>
>>> If you use /dev/random in the above command, you'll get the specified
>>> amount of random bytes.
>>>
>>
>> It should contain human readable data not he system readable data. If
>> i use dd if=/dev/random it is generation some system level data which
>> we can't read.
>
>Certainly it is human readable if you pipe it, e.g., through od(1).

/dev/urandom is better than /dev/random for junk data. Or maybe even
/dev/zero piped to hexdump. You can use a format with hexdump to
eliminate spaces in the output. I did not see a way to do that with od.



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From: John Kelly on 11 Aug 2010 11:51
On Wed, 11 Aug 2010 15:46:35 +0000, John Kelly <jak(a)isp2dial.com> wrote:

>/dev/urandom is better than /dev/random for junk data. Or maybe even
>/dev/zero piped to hexdump. You can use a format with hexdump to
>eliminate spaces in the output. I did not see a way to do that with od.

Whoops. hexdump can read /dev/zero directly, no pipe needed:

hj:~# hexdump -n 4 -v -e '/1 "%.2x"' /dev/zero
00000000

Just change the "-n 4" to the number of bytes you want.





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From: Janis Papanagnou on 11 Aug 2010 11:59
On 11/08/10 17:46, John Kelly wrote:
> On Wed, 11 Aug 2010 17:36:56 +0200, Janis Papanagnou
> <janis_papanagnou(a)hotmail.com> wrote:
>
>> On 11/08/10 17:04, srikanth wrote:
>>> On Aug 11, 8:55 am, Barry Margolin <bar...(a)alum.mit.edu> wrote:
>>>> In article
>>>> <9a7c7480-8de2-4c39-9da9-15fd9b111...(a)i19g2000pro.googlegroups.com>,
>>>> srikanth <srikanth0...(a)gmail.com> wrote:
>>>>> On Aug 10, 10:30 pm, pk <p...(a)pk.invalid> wrote:
>>>>>> On Tue, 10 Aug 2010 08:06:47 -0700 (PDT) srikanth <srikanth0...(a)gmail.com>
>>>>>> wrote:
>>>>
>>>>>>> Hi All,
>>>>>>> Just wanted to know if we can generate data with given input size with
>>>>>>> the help of shell script. Any idea from our group?
>> [...]
>>>>> I Just want to generate files with data. Any type of data that doesn't
>>>>> depend upon the content what it is..
>>>>> How can we do this with the help of awk or perl?
>>>>
>>>> If you use /dev/random in the above command, you'll get the specified
>>>> amount of random bytes.
>>>>
>>>
>>> It should contain human readable data not he system readable data. If
>>> i use dd if=/dev/random it is generation some system level data which
>>> we can't read.
>>
>> Certainly it is human readable if you pipe it, e.g., through od(1).
>
> /dev/urandom is better than /dev/random for junk data. Or maybe even
> /dev/zero piped to hexdump. You can use a format with hexdump to
> eliminate spaces in the output. I did not see a way to do that with od.
>
>
>

With od you can specify someting like -t x1 or whatever desired as
format. Postprocessing to remove the address or eliminate the blanks
is trivial.

I wonder, though, why you suggest /dev/zero. If the data is irrelevant
you can as well use something like

yes "The same line..." | head -100

yes "0" | tr -d $'\n' | head -1000

yes "0000000000" | tr -d $'\n' | head -100


Janis
From: Janis Papanagnou on 11 Aug 2010 12:02
On 11/08/10 17:51, John Kelly wrote:
> On Wed, 11 Aug 2010 15:46:35 +0000, John Kelly <jak(a)isp2dial.com> wrote:
>
>> /dev/urandom is better than /dev/random for junk data. Or maybe even
>> /dev/zero piped to hexdump. You can use a format with hexdump to
>> eliminate spaces in the output. I did not see a way to do that with od.
>
> Whoops. hexdump can read /dev/zero directly, no pipe needed:
>
> hj:~# hexdump -n 4 -v -e '/1 "%.2x"' /dev/zero
> 00000000
>
> Just change the "-n 4" to the number of bytes you want.

Okay. Then I'd use a shell builtin...

printf "%0*d", 78, 0

....will print 78 zeroes.

Janis
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