Am 12.03.2014 um 15:12 schrieb Lars Huttar <lars_huttar@sil.org>:

> On 3/12/2014 10:05 AM, Wolfgang Schuster wrote:
>> Am 12.03.2014 um 15:00 schrieb Lars Huttar <lars_huttar@sil.org>:
>> 
>>> Hello,
>>> I've got a running page head like this in my document:
>>> 
>>> \def\CurrentUser{\cldcontext{os.resultof"whoami"}}
>>> 
>>> \def\Markname { Compiled \date by \CurrentUser  \LUATEX +\ConTeXt\
>>> \contextversion }
>>> 
>>> and later:
>>> 
>>> \setlayer[cropmark][preset=lefttop,x=3cm,y=-1.5\lineheight]{\Markname}
>>> 
>>> But when I run this, I get a UCS error that seems to indicate that the
>>> *result* of \CurrentUser ("waxhaw\huttar") is getting parsed as a
>>> command sequence.
>> When you want to pass a backslash to Lua you have to use \letterbackslash.
>> 
> 
> Thanks... can you give me an example of what that would look like?
> I don't think I want to pass a backslash to Lua, so I'm not sure how to
> apply what you're saying. Or are you using "Lua" here in the sense of
> LuaTeX?
> 
> A backslash appears in the output of os.resultof"whoami"; do I need to
> perform some processing on that output in order to escape backslashes?


Try this:

\def\CurrentUser{\cldcontext{os.resultof"whoami"}}

\def\Markname{Compiled \date by \detokenize\expandafter{\CurrentUser} \LUATEX +\ConTeXt\ \contextversion.}

\setuplayout[location=middle,marking=on]

\definelayer[cropmark][state=repeat,width=\paperwidth,height=\paperheight]

\setupbackgrounds[page][background=cropmark]

\setlayer[cropmark][preset=lefttop,x=3cm,y=1.5\lineheight]{\Markname}

\starttext

Foo

\stoptext

Wolfgang