How to delete an unused server from GNUS

OK – the summary:

  1. Kill all groups in that server
  2. remove it from gnus.el config file
  3. quit gnus
  4. quit emacs
  5. restart emacs and gnus
  6. and the server is (hopefully) gone.

Long story: might follow some time…

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Things to do after installing OpenMediaVault

I started using OpenMediaVault as my NAS of choice. My reason: it includes plugins for running and installing Plex Media Server and VirtualBox. This makes it very handy, especially the Plex Media Server. And it is based on Debian.

This is work in progress and additions will follow.

Continue reading

Pogoplug as ftp server

The purpose is to have an ftp server so that otr files can be uploaded there via pushftp.

This is a throw-away configuration, quick to rebuild if necessary.

Install Debian as usual.

This is based on https://www.howtoforge.com/tutorial/proftpd-installation-on-debian-and-ubuntu/.

1 Install proftpd

  apt-get install proftpd-basic

1.1 ADDED: Add debian hostname to /etc/hosts

  echo "127.0.0.1 debian" >> /etc/hosts

1.2 Create user and groups

addgroup ftpgroup
adduser otrupload -shell /bin/false -home /ftpshare
adduser otrupload ftpgroup

1.3 Change permissions

chmod -R 1777 /ftpshare/

1.4 Adapt /etc/proftp/proftpd.conf

Add

<Global>
    RootLogin   off
    RequireValidShell off
</Global>

DefaultRoot  ~

<Limit LOGIN>
    DenyGroup !ftpgroup
</Limit>

Compile pdf-ftools on Mac – env settings

To compile pdf-tools under OS X:

The paths for the PKG_CONFIG_PATH have to be set before calling pdf-tools-install.

If they are set as follow (depending on via homebrew installed zlib package)

(setenv "PKG_CONFIG_PATH"
        (concat
         "/usr/local/Cellar/zlib/1.2.8/lib/pkgconfig:/usr/local/lib/pkgconfig:/opt/X11/lib/pkgconfig:"
         (getenv "PKG_CONFIG_PATH")))

After this,

pdf-tools-install

works without problems in emacs.

Always put comments in your code!

I have a paper which I wrote some years ago, which has not been finished, and which should be accompanied by an R package. So far nothing special, but at that time, I was only at the beginning of my affair with R, and so I made several mistakes (OK – I did also some things right – I hope). One thing which I did not think about (or cared about) was to comment my code. So now I am sitting in front of about 8 R files with strange names and no comments in them. Now:

What can I do with them?

One advantage: I have graphs, generated by R, in my draft paper – so I can trace my scripts back from the name of the graphs, identify the script which created the graphs, then to the data and finally (hopefully) have an idea how my script mess did what it was doing – and hopefully, I will be able to do this before retirement (which is still several years away).

Now – what could I have done better at that time? Well, there are several things:

  1. I could have used org-mode. Org-mode enables one to combine documentation and code in a single file. It is a literate programing at its best (more will likely follow later). In addition: it can easily exported to, among others, pdf and html, including code and text.
  2. But I used only ess. Nevertheless,  I could have added more comments in the code.

There is always the # in R!!!

I am not saying that org-mode would necessarily have saved me (even in org-mode you have to write the documentation and code yourself), but it would have pushed towards documentation, as the body of the text is the documentation, and you put the code in source blocks. At the first look, it sounds strange, but one usually starts with ideas about the code, a structure, notes for algorithms, charts, etc. and all these go into the document. And then, if one starts coding. And to each code block, there should be already some text which explains what it shlud be doing – and voilá, here is the basic documentation.

To execute the code blocks, one can either evaluate them in the document and insert the results, or “tangle” the document, which means extracting the source code into files. As it is possible to define into which file which code block should be extracted, one can create a complex system of resulting R files. And these R files, can then be sourced from R, running in ess / emacs.

The next possible step  would be then to put your script files into a package, which would then even ask for more documentation. And then there will Roxygen help – but that might be told in another blog.

So there are many tools which make documenting your R code easier, but you don’t have to use them.

I want to close with a quote from Donald Knuth. “Literate Programming (1984)” in Literate Programming. CSLI, 1992, pg. 99:

I believe that the time is ripe for significantly better documentation of programs, and that we can best achieve this by considering programs to be works of literature. Hence, my title: “Literate Programming.”

Let us change our traditional attitude to the construction of programs: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do.

The practitioner of literate programming can be regarded as an essayist, whose main concern is with exposition and excellence of style. Such an author, with thesaurus in hand, chooses the names of variables carefully and explains what each variable means. He or she strives for a program that is comprehensible because its concepts have been introduced in an order that is best for human understanding, using a mixture of formal and informal methods that reinforce each other.

 Cheers and enjoy life.

An intro

Well – everybody has to start sometime, and I will now.

But first some questions which might be asked about this blog:

  • About what: I’ll see – but likely about
    • R – the programming language for stats, but also for simulations, as it can interface easily with C/C++, Fortran, Java, …
    • GIS in the widest sense – I use GRASS and QGIS and GDAL and will possibly have something to say about those
    • org-mode ESS and emacsthe best and for me by now only way to write R code
    • Science – as I am a scientist, this is obvious. It will include spatial statistics, alien species, management, general scientific topics, …
    • Open source software – I use Linux (Ubuntu) and am of the opinion that whenever possible, open source software should be used, particularly  in research
  • Will I blog regular?
    • We’ll see, but I don’t think so. Blogging for the sense of blogging is useless. Also: I am lazy.
  • Who am I?
    • We’ll – let’s leave it at that: I am a scientist, who is blogging about the things I mentioned above.
    • Is more info relevant? I will reveal more possibly in later blogs.

So – let’s get started with my first blog about something relevant.