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Full Discussion: Difference between ">/dev/null 2>&1" and "2>&1 >/dev/null"
Top Forums Shell Programming and Scripting Difference between ">/dev/null 2>&1" and "2>&1 >/dev/null" Post 302380098 by Scott on Monday 14th of December 2009 08:24:28 AM
Old 12-14-2009
Hi.

They're not the same.

In the first case, standard output is directed to a file (in this case /dev/null), and then standard error is directed to the same place (&1, or /dev/null).

It's equivalent to

Code:
> /dev/null 2> /dev/null

In the second case, standard error is directed to where standard output is directed at the time (i.e. the screen), and then standard output is directed to somewhere else (/dev/null)

Code:
$ cat Test
echo stdout
echo stderr >&2

$ ./Test > /dev/null 2>&1
$

$ ./Test 2>&1 > /dev/null
stderr

 

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LEARN ABOUT ULTRIX

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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