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Full Discussion: How to output 1s endlessly like /dev/zero?
Top Forums UNIX for Advanced & Expert Users How to output 1s endlessly like /dev/zero? Post 302399283 by LessNux on Saturday 27th of February 2010 01:26:52 AM
Old 02-27-2010
Question
Quote:
Originally Posted by pludi
the resolution is simple.
Code:
perl -e 'print chr(0xFF) while(1);' | dd of=/dev/sdb


Thanks, pludi. However, is there any faster technique?

The technique "perl -e 'print chr(0xFF) while(1);'" is too slow compared to /dev/zero.

The "perl ... while" method is 400 times slower than /dev/zero, if there is almost no bottleneck by the output destination.

Even in a real world environment where the flow is bottlenecked by the slow hard drive, the "perl ... while" method is 2.5 times slower than /dev/zero.

Can anyone think of a technique to output 1's (0xFF or 0b11111111) endlessly nearly as fast as /dev/zero? Is it possible to custom-make a pseudo-device similar to /dev/zero?

Thanks a lot in advance.
 

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LEARN ABOUT OSX

msglog

msglog(7D)							      Devices								msglog(7D)

NAME

       msglog - message output collection from system startup or background applications

SYNOPSIS

       /dev/msglog

DESCRIPTION

       Output from system startup ("rc") scripts is directed to /dev/msglog, which dispatches it appropriately.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsr			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Stable			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       syslogd(1M), syslog(3C), attributes(5), sysmsg(7D)

NOTES

       In  the	current  version of Solaris, /dev/msglog is an alias for /dev/sysmsg.  In future versions of Solaris, writes to /dev/msglog may be
       directed into a	more general logging mechanism such as syslogd(1M).

       syslog(3C) provides a more general logging mechanism  than /dev/msglog and should be used in preference to /dev/msglog whenever possible.

SunOS 5.10							    13 Oct 1998 							msglog(7D)
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