check installed program using Lua

check installed program using Lua

[Pablo Rodriguez via ntg-context]

Dear list,

is there a way if a program is installed on the computer using Lua.

I have the following sample:

  \starttext
  \startluacode
  filename = tex.jobname .. ".pdf"
  os.exec("dir " .. filename)
  \stopluacode
  \stoptext

Is there a way to wrap os.exec() in the sample so that it only runs if
"dir" is available?

I know that os.name would be an option here, but not in my real world
document.

Many thanks for your help,

Pablo
--
http://www.ousia.tk
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Re: check installed program using Lua

[Taco Hoekwater via ntg-context]

> On 1 Nov 2021, at 14:26, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
> 
> Dear list,
> 
> is there a way if a program is installed on the computer using Lua.
> 
> I have the following sample:
> 
>  \starttext
>  \startluacode
>  filename = tex.jobname .. ".pdf"
>  os.exec("dir " .. filename)
>  \stopluacode
>  \stoptext
> 
> Is there a way to wrap os.exec() in the sample so that it only runs if
> "dir" is available?

if os.which(‘dir’) then
  ...
end

But note that os.which() may be unreliable in various cases (like it will fail for shell/command interpreter builtins, in cron jobs, in special scripted environments, and may incorrectly succeed for disabled/forbidden commands), as it just runs through the PATH environment variable to check for executable file existence. 

Often times, it is better to just try to run the command to see if that produces satisfactory results.

Best wishes,
taco

— 
Taco Hoekwater              E: taco@bittext.nl
genderfluid (all pronouns)



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Re: check installed program using Lua

[Pablo Rodriguez via ntg-context]

On 11/1/21 3:10 PM, Taco Hoekwater via ntg-context wrote:
>> [...]
>> Is there a way to wrap os.exec() in the sample so that it only runs if
>> "dir" is available?
>
> if os.which(‘dir’) then
>   ...
> end
>
> But note that os.which() may be unreliable in various cases (like it
> will fail for shell/command interpreter builtins, in cron jobs, in
> special scripted environments, and may incorrectly succeed for
> disabled/forbidden commands), as it just runs through the PATH
> environment variable to check for executable file existence.
Many thanks for your reply, Taco.

This is exactly what I needed.

> Often times, it is better to just try to run the command to see if
> that produces satisfactory results.
It makes sense, but I cannot do that on foreign computers.

Many thanks for your help again,

Pablo

--
http://www.ousia.tk
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___________________________________________________________________________________

Re: check installed program using Lua

[Hans Hagen via ntg-context]

On 11/1/2021 2:26 PM, Pablo Rodriguez via ntg-context wrote:
> Dear list,
> 
> is there a way if a program is installed on the computer using Lua.
> 
> I have the following sample:
> 
>    \starttext
>    \startluacode
>    filename = tex.jobname .. ".pdf"
>    os.exec("dir " .. filename)
>    \stopluacode
>    \stoptext
> 
> Is there a way to wrap os.exec() in the sample so that it only runs if
> "dir" is available?
> 
> I know that os.name would be an option here, but not in my real world
> document.

\starttext
   \startluacode
     if lfs.isfile(tex.jobname .. ".pdf") then
         context("YES")
     end
     if lfs.isfile(file.addsuffix(environment.outputfilename,"pdf")) then
         context("YES")
     end
     if #dir.glob(file.addsuffix(environment.outputfilename,"pdf")) > 0 then
         context("YES")
     end
   \stopluacode
\stoptext

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: check installed program using Lua

[Pablo Rodriguez via ntg-context]

On 11/1/21 5:13 PM, Hans Hagen via ntg-context wrote:
> On 11/1/2021 2:26 PM, Pablo Rodriguez via ntg-context wrote:
>> [...]
>> Is there a way to wrap os.exec() in the sample so that it only runs if
>> "dir" is available?
>>
>> I know that os.name would be an option here, but not in my real world
>> document.
>
> \starttext
>    \startluacode
>      if lfs.isfile(tex.jobname .. ".pdf") then
>          context("YES")
>      end
>      if lfs.isfile(file.addsuffix(environment.outputfilename,"pdf")) then
>          context("YES")
>      end
>      if #dir.glob(file.addsuffix(environment.outputfilename,"pdf")) > 0 then
>          context("YES")
>      end
>    \stopluacode
> \stoptext

Many thanks for your reply, Hans.

I can see that I explained my question poorly, but your code fits me in
other case.

Many thanks for your help,

Pablo
--
http://www.ousia.tk
___________________________________________________________________________________
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________