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Re: My script almost works but spams the terminal its launched from if useing dash.

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On 04/17/2016 03:21 AM, Jeremy Nicoll wrote:
> On Sun, 17 Apr 2016, at 07:25, Michael Milliman wrote:
>
>> Yes, this is the correct incantation.  The difference is very subtle.
>> With ... 2>&1 >/dev/null, the error output is redirected to be the same
>> as the standard output, and then the standard output is redirected to
>> /dev/null -- leaving the error output still going to the original
>> standard output (terminal).
> Why is the "2>&1" part needed?   Wouldn't stderr go to the terminal by
> default?
>
stderr goes to terminal by default, yes.  And in the first, incorrect 
incantation ...2>&1 >/dev/null, the redirection of the stderr to the 
same as stdout has basically no effect, though it does in theory 
redirect the stderr to the same place as stdout. In the second 
incantation ...>/dev/null 2>&1 the stdout is first redirected where you 
want the ouput to go, then the stderr is sent to the same place as 
stdout.  This has the effect of redirecting both outputs to /dev/null, 
whereas the incorrect syntax leaves the stderr going to the terminal 
while stdout is properly redirected this is the same effect as if the 
2>&1 portion was not present because it was processed before the 
redirection of stdout to /dev/null.  Bash processes the redirections in 
order as it reads them on the command line, and acts appropriately.

-- 
Mike

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My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-16 17:30 +0200
  Re: My script almost works but spams the terminal its launched from  if useing dash. Aero Maxx <aero.maxx.d@gmail.com> - 2016-04-16 18:10 +0200
    Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-16 18:50 +0200
      Re: My script almost works but spams the terminal its launched from  if useing dash. Aero Maxx <aero.maxx.d@gmail.com> - 2016-04-16 19:20 +0200
        Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-17 00:50 +0200
        Re: My script almost works but spams the terminal its launched from  if useing dash. Michael Milliman <michael.e.milliman@gmail.com> - 2016-04-17 08:30 +0200
          Re: My script almost works but spams the terminal its launched from if  useing dash. Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2016-04-17 13:00 +0200
            Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-17 13:50 +0200
              Re: My script almost works but spams the terminal its launched from if  useing dash. Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2016-04-17 15:10 +0200
                Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-17 15:30 +0200
                Re: My script almost works but spams the terminal its launched from  if useing dash. Michael Milliman <michael.e.milliman@gmail.com> - 2016-04-17 15:40 +0200
                Re: My script almost works but spams the terminal its launched from if  useing dash. Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2016-04-17 16:40 +0200
            Re: My script almost works but spams the terminal its launched from  if useing dash. Michael Milliman <michael.e.milliman@gmail.com> - 2016-04-17 15:30 +0200
          Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-17 13:50 +0200
        Re: My script almost works but spams the terminal its launched from  if useing dash. Andrew McGlashan <andrew.mcglashan@affinityvision.com.au> - 2016-04-22 06:30 +0200
          Re: My script almost works but spams the terminal its launched from  if useing dash. Michael Milliman <michael.e.milliman@gmail.com> - 2016-04-22 07:00 +0200
            Re: Re: My script almost works but spams the terminal its launched  from if useing dash. Clive Standbridge <list-user@tgstandbridges.plus.com> - 2016-04-22 11:40 +0200
          Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-22 10:30 +0200
          Re: My script almost works but spams the terminal its launched from  if useing dash. David Wright <deblis@lionunicorn.co.uk> - 2016-04-22 13:10 +0200
  Re: My script almost works but spams the terminal its launched from if useing dash. Sven Joachim <svenjoac@gmx.de> - 2016-04-16 18:50 +0200
    Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-16 19:10 +0200
      Re: My script almost works but spams the terminal its launched from  if useing dash. Linux-Fan <Ma_Sys.ma@web.de> - 2016-04-16 19:30 +0200
      Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-16 20:10 +0200
        Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-17 01:10 +0200
          Re: My script almost works but spams the terminal its launched from  if useing dash. David Wright <deblis@lionunicorn.co.uk> - 2016-04-17 04:30 +0200
            Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-17 06:50 +0200
              Re: My script almost works but spams the terminal its launched from  if useing dash. David Wright <deblis@lionunicorn.co.uk> - 2016-04-18 16:00 +0200
                Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-18 20:50 +0200
          Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-17 14:10 +0200
          Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-17 14:10 +0200
            Re: My script almost works but spams the terminal its launched from if useing dash. Gene Heskett <gheskett@shentel.net> - 2016-04-17 15:20 +0200
              Re: My script almost works but spams the terminal its launched from if useing dash. "Thomas Schmitt" <scdbackup@gmx.net> - 2016-04-17 16:40 +0200

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