On Sunday 17 April 2016 02:25:01 Michael Milliman wrote: > On 04/16/2016 12:11 PM, Aero Maxx wrote: > > On 16/04/2016 17:45, Gene Heskett wrote: > >> On Saturday 16 April 2016 12:01:28 Aero Maxx wrote: > >>> On 16/04/2016 16:23, Gene Heskett wrote: > >>>> But when I run it with dash, it doesn't seem to work right, and > >>>> spams the terminal with its error messages. One that appears to > >>>> kill its function is the bashism of using [[ ]] to surround > >>>> string variables, reported like this: > >>>> bin/mailwatcher: 64: bin/mailwatcher: [[: not found > >>>> bin/mailwatcher: 70: bin/mailwatcher: [[: not found > >>>> bin/mailwatcher: 77: bin/mailwatcher: [[: not found > >>> > >>> dash isn't the same as bash, as it has a limited set of > >>> instructions or commands it can do. > >>> > >>> But I too would be interested to know if it is possible to get it > >>> to work in dash, I don't believe it is, but I am happy to be > >>> corrected or proved wrong. > >>> > >>>> And finally, once its working with either shell, how do I shut it > >>>> up totally? Even the above command line launch fails as it > >>>> outputs to that shell, a newline for every incoming mail which > >>>> gradually scrolls any output that was on-screen, offscreen > >>>> without leaving a prompt until I tap the return key to restore > >>>> it. > >>> > >>> Also isn't the command you are running supposed to be as follows ? > >>> > >>>> bin/mailwatcher 2>&1 > /dev/null & > >> > >> Is the space you inserted into my line between the > and the > >> /dev/null a game changer? In either bash or dash? Its been a while > >> since I last read the bash docs, but I don't recall there was any > >> emphasis on that. > > > > I'm sorry I was a bit too eager to reply and neglected to change > > what I had pasted in. > > > > I meant to say could you try this > > > >> bin/mailwatcher > /dev/null 2>&1 & > > Yes, this is the correct incantation. The difference is very subtle.
And not very well noted in the bash .pdf or the man page. > 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). With ... >/dev/null 2>&1 The > standard output is redirected first, and the the error output is sent > to the same place as the standard output, resulting in both going to > /dev/null. The order of redirection is important to the end results > in this case. Good to know, and thank you. > > This email has been checked for viruses by Avast antivirus software. > > https://www.avast.com/antivirus Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene>
