[ncl-talk] ncl systemfunc

[Rick Brownrigg]

Hi Matthias,

I think maybe we have explaination.  The so-called "brace-expansion"
appears to be a bash thing. I speculate your shell in your terminal window
is indeed bash.  However, by default, NCL under the covers invokes
"/bin/sh" during the systemfunc() call. On many Linux systems, /bin/sh is
simply a symlink to bash (that's the case on my system and why things work
for me).  However, apparently on Ubuntu systems, /bin/sh is a symlink to a
shell called "dash" (I'd never heard of it), and dash is the one that does
not understand brace-expansion -- you can try it yourself by invoking
"dash" on the command-line and then trying a command that involves
brace-expansion.  More on this here:

    http://askubuntu.com/questions/87853/what-is-default-shell-for-terminal

So a solution in your case would be something like this:

    files = systemfunc("bash -c 'ls /DIRECTORY/*{.nc,.hdf,.pdf}'")

In particular note the "-c" switch to bash, and that the command you want
bash to execute is surrounded by single-quotes.

Hope that helps...
Rick

On Fri, Feb 10, 2017 at 12:54 PM, Matthias Demuzere <
Matthias.Demuzere at ugent.be> wrote:

> Hi Rick,
>
> Yes... I tested this for a single string without curly brackets (eg. *.nc)
> and that works fine ...
> Does this indicate there is somehow a system dependency, even though the
> curly brackets do work directly in the terminal? Quite puzzling, no?
>
> Matthias
>
> On 10 Feb 2017 18:30, Rick Brownrigg <brownrig at ucar.edu> wrote:
>
> Hi Matthias,
>
> That is very odd -- it works for me, both at bash command line and using
> systemfunc() from within NCL.  Can you get systemfunc to return files from
> a directory without using "{}" notation, .i.e, "ls *" for example? Or
> simply "ls foo" where the file foo is known to exist in the current
> directory?
>
> Rick
>
> On Fri, Feb 10, 2017 at 10:15 AM, Matthias Demuzere <
> matthias.demuzere at ugent.be> wrote:
>
> Dear all,
>
> I am currently testing the CVDP (http://www.cesm.ucar.edu/work
> ing_groups/CVC/cvdp/) which is written in ncl.
> Currently the software does not run because it can't find the proper
> datasets.
>
> Finding the data is driven by the *systemfunc* command using curly
> brackets (multiple options).
> For example, within ncl, I want to list all files that have one of the
> following extension: .nc, .hdf, .pdf.
>
> This I do with:
> myFiles = systemfunc("ls /DIRECTORY/*{.nc,.hdf,.pdf}")
>
> If I fo this in ncl, I get an error: ls: cannot access
> '/DIRECTORY/*{.nc,.hdf,.pdf}': No such file or directory
>
> Yet, when pasting ls /DIRECTORY/*{.nc,.hdf,.pdf} directly in my system
> (ubuntu 16.04, 64bit) terminal, I do get a list of the finals with this
> extension. So the expected result.
>
> I have tested this in ncl-6.3.0 and 6.2.1, but I have the same problem in
> both.
> Did anyone else notice this before? Any idea on how to fix this?
>
> Thanks!
>
> Regards,
> Matthias
>
>
> --
> Post-doctoral Research Fellow
> _____________________________
>
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>
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