Generating data depending upon the given size
in [Shell]
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From: John Kelly on 11 Aug 2010 12:07 On Wed, 11 Aug 2010 18:02:55 +0200, Janis Papanagnou <janis_papanagnou(a)hotmail.com> wrote: >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. I wonder if that will scale to large numbers. -- Web mail, POP3, and SMTP http://www.beewyz.com/freeaccounts.php
From: Janis Papanagnou on 11 Aug 2010 14:21 On 11/08/10 18:07, John Kelly wrote: > On Wed, 11 Aug 2010 18:02:55 +0200, Janis Papanagnou > <janis_papanagnou(a)hotmail.com> wrote: > >> 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. > > I wonder if that will scale to large numbers. The OP asked for 5 MB and the ksh-builtin printf supports more than 1 GB of 0-paddings, likely due to the internal restriction on how large an integral number can be; so I presume it supports up to and not more than 2^31-1 digits that way. Janis > > >
From: srikanth on 13 Aug 2010 00:06 On Aug 11, 11:21 pm, Janis Papanagnou <janis_papanag...(a)hotmail.com> wrote: > On 11/08/10 18:07, John Kelly wrote: > > > > > On Wed, 11 Aug 2010 18:02:55 +0200, Janis Papanagnou > > <janis_papanag...(a)hotmail.com> wrote: > > >> On 11/08/10 17:51, John Kelly wrote: > >>> On Wed, 11 Aug 2010 15:46:35 +0000, John Kelly <j...(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. > > > I wonder if that will scale to large numbers. > > The OP asked for 5 MB and the ksh-builtin printf supports more than 1 GB > of 0-paddings, likely due to the internal restriction on how large an > integral number can be; so I presume it supports up to and not more than > 2^31-1 digits that way. > > Janis > > even /dev/random is showing junk data. How can i generate a file with data where human can readable.
From: Bill Marcum on 13 Aug 2010 05:05
On 2010-08-13, srikanth <srikanth007m(a)gmail.com> wrote: >> > > even /dev/random is showing junk data. How can i generate a file with > data where human can readable. od </dev/random -- Vacuums are nothings. We only mention them to let them know we know they're there. |