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Top Forums UNIX for Advanced & Expert Users Redirection? (I do find some of the strangest things.) Post 302989215 by wisecracker on Tuesday 10th of January 2017 04:41:43 AM
Old 01-10-2017
Redirection? (I do find some of the strangest things.)

(Apologies for any typos.)
Can someone help me with this one please.
I am writing a snippet that will come on here soon to work on OSX, Linux and CygWin but I hit this!

I hope this is lucid enough because I really do not understand what is going on.

Take these few lines:-
Code:
#!/bin/sh
# OR #!/usr/local/bin/dash
> /tmp/noise.raw
> /dev/null 2>&1 cat /tmp/noise.raw > /dev/dsp

And tested in ShellCheck gives this:-
Code:
$ shellcheck myscript
 
Line 3:
> /tmp/noise.raw
^-- SC2188: This redirection doesn't have a command. Move to its command (or use 'true' as no-op).

$

OK so I add a NOP:-
Code:
#!/bin/sh
# OR #!/usr/local/bin/dash
: > /tmp/noise.raw
> /dev/null 2>&1 cat /tmp/noise.raw > /dev/dsp

And tested in ShellCheck gives NO error:-
Code:
$ shellcheck myscript
No issues detected!

$

Why is a redirection to > /dev/null allowed to be a _direct_ redirection and yet : > /tmp/noise.raw requires a NOP?

Next question is this line, > /dev/null 2>&1 cat /tmp/noise.raw > /dev/dsp actually works to hide an OSX error, paraphrasing, 'I don't have permssion to access this' which is obvious as OSX does not have '/dev/dsp'.
This line also runs correctly on CygWin with > /dev/null 2>&1 at the start. So it looks like I have done something correct but don't know why?

TIA.

Barry.
 

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Bio::Structure::Atom(3pm)				User Contributed Perl Documentation				 Bio::Structure::Atom(3pm)

NAME
Bio::Structure::Atom - Bioperl structure Object, describes an Atom SYNOPSIS
#add synopsis here DESCRIPTION
This object stores a Bio::Structure::Atom FEEDBACK
Mailing Lists User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to one of the Bioperl mailing lists. Your participation is much appreciated. bioperl-l@bioperl.org - General discussion http://bioperl.org/wiki/Mailing_lists - About the mailing lists Support Please direct usage questions or support issues to the mailing list: bioperl-l@bioperl.org rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible. Reporting Bugs Report bugs to the Bioperl bug tracking system to help us keep track the bugs and their resolution. Bug reports can be submitted via the web: https://redmine.open-bio.org/projects/bioperl/ AUTHOR - Kris Boulez Email kris.boulez@algonomics.com APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _ new() Title : new() Usage : $struc = Bio::Structure::Atom->new( -id => 'human_id', ); Function: Returns a new Bio::Structure::Atom object from basic constructors. Probably most called from Bio::Structure::IO. Returns : a new Bio::Structure::Atom object x() Title : x Usage : $x = $atom->x($x); Function: Set/gets the X coordinate for an Atom Returns : The value for the X coordinate of the Atom (This is just a number, it is expected to be in Angstrom, but no garantees) Args : The X coordinate as a number y() Title : y Usage : $y = $atom->y($y); Function: Set/gets the Y coordinate for an Atom Returns : The value for the Y coordinate of the Atom (This is just a number, it is eypected to be in Angstrom, but no garantees) Args : The Y coordinate as a number z() Title : z Usage : $z = $atom->z($z); Function: Set/gets the Z coordinate for an Atom Returns : The value for the Z coordinate of the Atom (This is just a number, it is ezpected to be in Angstrom, but no garantees) Args : The Z coordinate as a number xyz() Title : xyz Usage : ($x,$y,$z) = $atom->xyz; Function: Gets the XYZ coordinates for an Atom Returns : A list with the value for the XYZ coordinate of the Atom Args : residue() Title : residue Usage : Function: No code here, all parent/child stuff via Entry Returns : Args : icode() Title : icode Usage : $icode = $atom->icode($icode) Function: Sets/gets the icode Returns : Returns the icode for this atom Args : reference to an Atom serial() Title : serial Usage : $serial = $atom->serial($serial) Function: Sets/gets the serial number Returns : Returns the serial number for this atom Args : reference to an Atom occupancy() Title : occupancy Usage : $occupancy = $atom->occupancy($occupancy) Function: Sets/gets the occupancy Returns : Returns the occupancy for this atom Args : reference to an Atom tempfactor() Title : tempfactor Usage : $tempfactor = $atom->tempfactor($tempfactor) Function: Sets/gets the tempfactor Returns : Returns the tempfactor for this atom Args : reference to an Atom segID() Title : segID Usage : $segID = $atom->segID($segID) Function: Sets/gets the segID Returns : Returns the segID for this atom Args : reference to an Atom pdb_atomname() Title : pdb_atomname Usage : $pdb_atomname = $atom->pdb_atomname($pdb_atomname) Function: Sets/gets the pdb_atomname (atomname used in the PDB file) Returns : Returns the pdb_atomname for this atom Args : reference to an Atom element() Title : element Usage : $element = $atom->element($element) Function: Sets/gets the element Returns : Returns the element for this atom Args : reference to an Atom charge() Title : charge Usage : $charge = $atom->charge($charge) Function: Sets/gets the charge Returns : Returns the charge for this atom Args : reference to an Atom sigx() Title : sigx Usage : $sigx = $atom->sigx($sigx) Function: Sets/gets the sigx Returns : Returns the sigx for this atom Args : reference to an Atom sigy() Title : sigy Usage : $sigy = $atom->sigy($sigy) Function: Sets/gets the sigy Returns : Returns the sigy for this atom Args : reference to an Atom sigz() Title : sigz Usage : $sigz = $atom->sigz($sigz) Function: Sets/gets the sigz Returns : Returns the sigz for this atom Args : reference to an Atom sigocc() Title : sigocc Usage : $sigocc = $atom->sigocc($sigocc) Function: Sets/gets the sigocc Returns : Returns the sigocc for this atom Args : reference to an Atom sigtemp() Title : sigtemp Usage : $sigtemp = $atom->sigtemp($sigtemp) Function: Sets/gets the sigtemp Returns : Returns the sigtemp for this atom Args : reference to an Atom aniso() Title : aniso Usage : $u12 = $atom->aniso("u12", $u12) Function: Sets/gets the anisotropic temperature factors Returns : Returns the requested factor for this atom Args : reference to an Atom, name of the factor, value for the factor id() Title : id Usage : $atom->id("CZ2") Function: Gets/sets the ID for this atom Returns : the ID Args : the ID _remove_residue() Title : _remove_residue Usage : Function: Removes the Residue this Atom is atttached to. Returns : Args : _grandparent() Title : _grandparent Usage : Function: get/set a symbolic reference to our grandparent Returns : Args : perl v5.14.2 2012-03-02 Bio::Structure::Atom(3pm)
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