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diff --git a/content/pages/notes.rst b/content/pages/notes.rst new file mode 100644 index 0000000..19f6850 --- /dev/null +++ b/content/pages/notes.rst @@ -0,0 +1,154 @@ +:title: Notes +:status: published + +This is a collection of useful free software and commands for various purposes. + +.. contents:: + +Debian +###### + +Live image +---------- + +Sometimes it's quite useful to have your own custom live system image on a USB stick or a CD, e.g. to save a broken installation or to do maintenance work that cannot be done when the system is running. Building a custom image makes it possible to include software packages that are not included by default and to change the general configuration to your liking. + +Set up a basic config according to the `manual <https://debian-live.alioth.debian.org/live-manual/stable/manual/html/live-manual.en.html>`_. If the correct directory structure is there and you are able to build the default image, add a `list with additional packages you want <https://debian-live.alioth.debian.org/live-manual/stable/manual/html/live-manual.en.html#864>`_. + +My config command looks like this: + +.. code-block:: shell + + lb config --bootappend-live \ + "boot=live config locales=de_DE.UTF-8 keyboard-layouts=de username=wolfi" \ + --debian-installer live + +This command ensures a that the image has a German locale and keyboard layout. I also specify a custom user name to login. The default password is "live". With this config, it's possible to install the system to a disk. + +Package building +---------------- + +When I build a Debian package from its sources, I only sometimes want to make actual changes to the source code. In most cases, I want to do a `simple backport <https://wiki.debian.org/SimpleBackportCreation>`_ of a newer package from Testing or Unstable. So it's very annoying if the package build includes test cases that take quite some time to run. You can add ``DEB_BUILD_OPTIONS=nocheck`` to your ``dpkg-buildpackage`` command to skip the test cases. + + +Emacs +##### + +I do nearly all my text editing in Emacs. I write all my code in Emacs, edit configuration files in Emacs, write Latex documents with the great `AUCTEX <https://www.gnu.org/software/auctex/>`_ package and do my email with `mu4e <https://www.djcbsoftware.nl/code/mu/mu4e.html>`_. You can find a partially cleaned up version of my Emacs config file `here <https://code.fossencdi.org/config.git/tree/emacs>`_. I use the `"tomorrow" theme <https://github.com/purcell/color-theme-sanityinc-tomorrow>`_. Packages are maintained with `El-Get <http://tapoueh.org/emacs/el-get.html>`_. + +To securely send email in Emacs, I do certificate pinning with GnuTLS as described `here <https://blogs.fsfe.org/jens.lechtenboerger/2014/03/10/certificate-pinning-with-gnutls-in-the-mess-of-ssltls/>`__. My mail server uses `Let’s Encrypt <https://letsencrypt.org/>`_, so I have to do the pinning every two months. The procedure is as follows: + +.. code-block:: shell + + $ gnutls-cli --tofu --crlf --starttls -p 587 example.com + EHLO localhost + STARTTLS + +Then press ``Ctrl-D``. + +If you work with others on a software project or if you want to write clean code in general, it's important to properly use whitespace. With the command ``whitespace-cleanup``, you can get rid of unnecessary whitespace at the end of lines or in otherwise empty lines. + +Open a file as root in Emacs: + +.. code-block:: shell + + C-x C-f /sudo::/path/to/file + + +Files +##### + +Count number of words in a PDF document: + +.. code-block:: shell + + pdftotext <FILE> - | tr -d '.' | wc -w - + + +Network +####### + +View network connections continously: + +.. code-block:: shell + + netstat -t -u -c + +List the programs that currently use a specific network interface: + +.. code-block:: shell + + sudo nethogs <INTERFACE> + + + +Profiling applications +###################### + +Collect function calls with callgrind without fancy options: + +.. code-block:: shell + + valgrind --tool=callgrind <APP> + +Results can be viewed in KCachegrind. + + +Media +##### + +I do all my video editing with the allrounder `Blender <https://www.blender.org/>`_. Vector graphics are created in `Inkscape <https://inkscape.org/en/>`_. + +Photos +------ + +`Geeqie <http://geeqie.sourceforge.net/>`_ is a really nice and fast program to browse the RAW image files of your camera. I get the best out of my RAW images by editing them with `Rawtherapee <http://www.rawtherapee.com/>`_. `Gimp <https://www.gimp.org/>`_ is used for everything else that Rawtherapee can't do. HDR images can be created with `Luminance HDR <http://qtpfsgui.sourceforge.net/>`_. + +If I want to publish an image on the web, I first export it as JPEG, remove EXIF data with ``exiftool -all= IMAGE.jpg`` and optimize it with ``jpegoptim -s IMAGE.jpg``. + +Record screen +------------- + +Set the screen size with the ``-s`` option: wuxga for 1920x1200 and wxga for 1366x768. + +.. code-block:: shell + + avconv -f x11grab -s wuxga -r 25 -i :0.0 -qscale 5 -an OUTPUT.avi + + +Openwrt +####### + +I build the `Openwrt <https://openwrt.org/>`_ images for my routers from source. This way I can benefit from the security updates that are backported to the stable branches. The official prebuilt images are normally not updated when there are security issues. Additionally, I can add packages to the image, so I don't have to rely on the binary package manager. This also saves space. To update the sources, a few steps are needed: + +.. code-block:: shell + + git pull + ./scripts/feeds update -a + ./scripts/feeds install -a + +The newly build images can be found in the ``bin`` folder in a directory with the name of the platform the router is based on. + +I use `Unbound <https://unbound.net/>`_ as a recursive DNS resolver on my routers for all devices that are behind it. After upgrading the routers, it's necessary to sync the time. Otherwise, resolving DNS entries will fail. + + +Replicant +######### + +The phone's storage can be manually mounted with ``jmtpfs /media/phone/`` and unmounted with ``fusermount -u /media/phone``. + +I work on a `Replicant version based on CyanogenMod 13 <https://redmine.replicant.us/boards/21/topics/12057>`_. Alpha releases are tagged on the stable branch. There are too many git repositories in order to do the tagging manually, so I came up with two commands. First to add signed tags to all the repos that are directly mirrored from CyanogenMod: + +.. code-block:: shell + + repo forall $(repo forall -c ' echo "$REPO_REMOTE$REPO_PROJECT" | grep cm-mirror | cut -c10-') \ + -c ' git tag -s replicant-6.0-alpha-0002 -m "second alpha release of Replicant 6.0" && \ + git push git@fossencdi.org:cm-mirror/$REPO_PROJECT replicant-6.0-alpha-0002 ' + +Then sign all the modified repos: + +.. code-block:: shell + + repo forall $(repo forall -c ' echo "$REPO_REMOTE$REPO_PROJECT" | grep fossencdi | cut -c10-') \ + -c ' git tag -s replicant-6.0-alpha-0002 -m "second alpha release of Replicant 6.0" && \ + git push git@fossencdi.org:$REPO_PROJECT replicant-6.0-alpha-0002 ' |