Category: linux

Netbeans is a great open source Java IDE. For some reason it is missing from the current stable repository on debian. In order to get it installed as a regular desktop application in Debian Jessie (using GNOME) you should do the following:

1. JDK 8 is required in order to use netbeans. The default-jdkpackage on Jessie installs jdk7. First you must enable debian backportsand then you You can install it with sudo apt install -t jessie-backports openjdk-8-jdk
2. Download the latest version from the releases page. There are a couple different flavors. I usually choose the one that contains everything. This will download a bash installer script.
3. Open up a terminal and navigate to wherever you downloaded the script from Step 2. Execute the script with sh netbeans*.sh
4. This will run some pre-flight checks and then fire up an installation wizard that will guide you through the rest of the process.
5. Once Netbeans has been installed you can launch it by clicking on the icon that should now be on your desktop.

The Debian Policy Manual dictates that all packages should come with documentation. In order to save space in the debian archive these documents need to be compressed with gzip. There are a ton of these files floating around in the /usr/share/doc directory. Recently I wanted to read some of the documentation. If you try to open the file with cat it spits out binary gibberish. You can of course unzip the file as you normally would and open it up that way, but it turns out there is an easier way. Using zcat you can read the contents of compressed files just like you would with cat.

zcat is identical to gunzip -c. (On some systems, zcat may be installed as gzcat to preserve the original link to compress.) zcat uncompresses either a list of files on the command line or its standard input and writes the uncompressed data on standard output. zcat will uncompress files that have the correct magic number whether they have a .gz suffix or not. GZIP(1) man page.

By default, this will put all of the output into your terminal window, which is fine for most files. The other place where this can come in handy is when you are trying to look through compressed log files. In this case, having to scroll around the terminal may not be a great option. You can pipe the output of zcat into other programs such asless in order to be able to page through long files. For example, if I wanted to read the first 10 lines of a compressed log file, I could do so with the following command:

levlaz@debvm:/var/log$ sudo zcat syslog.2.gz | head -n 10

The output of this command would look like this:

May  2 22:27:43 debvm rsyslogd: [origin software="rsyslogd" swVersion="8.4.2" x-pid="585" x-info="http://www.rsyslog.com"] start
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1a] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1b] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1c] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1d] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1e] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x1f] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x20] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x21] high edge lint[0x1])
May  2 22:27:43 debvm kernel: [    0.000000] ACPI: LAPIC_NMI (acpi_id[0x22] high edge lint[0x1])

Many new and existing Debian users want to help make the distribution  better but do not quite know where to begin. Debian comes with a very handy package called how-can-i-help which tells you after each aptinvocation the current bugs that are associated with packages on your system. The “Work-Needing and Perspective Packages” (WNPP) listing is a bit overwhelming for new contributors. What better way to figure out what packages need your help than by seeing a list of them each time you use apt.

The first time you run apt after installing this package it will likely spit out a long list of packages that need your help. Each subsequent time it will only show new packages or changes. In order to see the master list again you can use the how-can-i-help --old command to see all packages that need your help. I think this is a great way to get engaged with the software that you rely on each day.

Although getting started with Debian development is not trivial, this lowers the barrier a bit and provides some clear direction on what to work on since the list includes packages that you are using every day.

Debian comes with a very handy utility called update-alternatives that helps to set default tools for various tasks.

It is possible for several programs fulfilling the same or similar functions to be installed on a single system at the same time. For example, many systems have several text editors installed at once. This gives choice to the users of a system, allowing each to use a different editor, if desired, but makes it difficult for a program to make a good choice for an editor to invoke if the user has not specified a particular preference.

On Linode, it seems that the default editor is nano, I prefer to use vim for editing git commits, visudo, and other things that use the default editor which is symbolically linked through /usr/bin/editor. The update-alternatives package basically changes the symbolic links for you. In order to change your default editor, you simply need to run the following command:

sudo update-alternatives --config editor

The output of this command is shown below. You will see a list of all of your editors that you currently have installed and will be asked to make a choice.

There are 3 choices for the alternative editor (providing /usr/bin/editor).

Selection Path Priority Status
------------------------------------------------------------
 0 /bin/nano 40 auto mode
 1 /bin/nano 40 manual mode
 2 /usr/bin/vim.basic 30 manual mode
* 3 /usr/bin/vim.tiny 10 manual mode

Press enter to keep the current choice[*], or type selection number:

Behind the scenes you can see that all this does it updates the symbolic links.

levlaz@dev:~$ ls -al /usr/bin/editor
lrwxrwxrwx 1 root root 24 Feb 10 20:49 /usr/bin/editor -> /etc/alternatives/editor
levlaz@dev:~$ ls -al /etc/alternatives/editor
lrwxrwxrwx 1 root root 17 Apr 28 18:56 /etc/alternatives/editor -> /usr/bin/vim.tiny

There are many other things that can be configured this way. For more information reading the man page for update-alternatives is worthwhile.

Here’s to the crazy ones, the misfits, the rebels. The package makers, the man page writers. The rounded windows in Qt mixed with the less rounded windows of GTK. The ones who literally see things differently because of missing proprietary fonts.

They’re not fond of rules, installation wizards, double clicking and have no respect for the status quo.

You can downvote them, disagree with them, glorify or vilify them. About the only thing you cannot do is ignore them. Because they ship your bug fixes.

They invent. They imagine. They heal. They explore. They create. They inspire. They push the human race forward.

Maybe they have to be crazy. How else can you stare at an empty screen and know that you have to blacklist your video card driver? Or sit in silence while tweaking alsamixer on the command line? Or write bash aliases to reload your network driver kernel module each time your laptop resumes from suspension? We make tools for these kinds of people.

While some may see them as the crazy ones, we see genius. Because people who are crazy enough to think that they can run Linux on the desktop, are the ones who change the world.

When I think of bash, I think of writing hacky scripts that do random things utilizing “bash commands”. It turns out that the parts of bash that “do stuff” such as echo, cut, cat are part of a larger program called GNU Core Utilities.

The GNU Core Utilities are the basic file, shell and text manipulation utilities of the GNU operating system.These are the core utilities which are expected to exist on every operating system.

Source: Coreutils – GNU core utilities I am working on a general purpose backup utility and this evening I was moments away from writing something like this: perl -e (print split("/\//", "/foo/bar/baz.tar.gz")

My goal was to try to extract the base file name from a given directory (I recognize that that code does not actually do that). Then I realized that this was pure madness and there had to be a better way. This is when I discovered the handy basename program. It simply does the needful. GNU Core Utilities is full of all sorts of gems such as this one. My main takeaway from this is to read the entire GNU Core Utilities manual so I can stop writing horrible things.

I just opened up a command prompt on Windows 10, typed in bash, and watched as Ubuntu was installed on my computer.

I never, in 1 million years, thought that I would ever live to see the day that this happened. With each passing announcement, upgrade, release, and blog post Microsoft is proving itself to be an innovative company once again. I have never been more excited about Windows than I am right now.

1. This completely changes most of the things I said in this post.
2. I have been saying for a while that I predict that the next version of Windows Server will basically be a Linux Distro. I think we are one step closer to making this a reality, and I think that this changes everything.
3. I am so excited to see what will happen in the future with this partnership.

You can read more details here. My mind is too blown to say anything else about this right now.

I’ve been working with Alpine Linux this week. This tiny Linux distribution is an excellent choice for a base docker image or, in my case, for a low power VPS. I love how easy and fast it is to install and configure this distribution.

One stumbling block that I ran into was downloading random things from the internet with wget.

Unable to locally verify the issuer's authority.
To connect to dl.eff.org insecurely, use `--no-check-certificate'

I saw this timely tweet by Joe Gross the other day and decided that rather than ignoring the error messages that wget was throwing I would go and figure out what was wrong.

It turns out that when you make an 83MB distribution you need to cut some of the fat. The ca-certificates package that is common in every Linux Distribution under the sun is missing from the default installation of Alpine.

In order to resolve the angry warnings from wget, you can install the ca-certificates package with the following command:

apk -U add ca-certificates

This will make wget happy, and your server secure. In case you are wondering, skipping this step and running wget with --no-check-certificate totally works. However, it is also inviting a man in the middle attack. Don’t ever do this.

I have been using Linux for many years, but only recently found out about /etc/motd. When you SSH into a server, it displays a message that varies depending on your Linux distribution. For instance, a stock Debian installation looks like this:

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Wed Sep 14 23:38:34 2016
user@hostname:~#

I never thought to look at where this message comes from, but apparently it lives in /etc/motd. I believe this stands for “message of the day”. This means that you can have this message say anything that you would like by editing the contents of /etc/motd. For example, you can use this Text to ASCII generator to put the hostname of your server in stunning ASCII text and make it look like this:

Levs-MacBook-Pro:~ levlaz$  ssh dev.levops.net
     _            _                                        _
  __| | _____   _| | _____   _____  _ __  ___   _ __   ___| |_
 / _` |/ _ \ \ / / |/ _ \ \ / / _ \| '_ \/ __| | '_ \ / _ \ __|
| (_| |  __/\ V /| |  __/\ V / (_) | |_) \__ \_| | | |  __/ |_
 \__,_|\___| \_(_)_|\___| \_/ \___/| .__/|___(_)_| |_|\___|\__|
                                   |_|

dev:~#

This is pretty neat! You can also do some fancy things like Ubuntu does and make this message change depending on various events such as security updates being available or a server restart being required. You can explore the scripts that Ubuntu uses in the /etc/update-motd.d/directory on a standard install.

Ah Slack, the email killer, the bane of my existence. Now in stunning Ubuntu 3d. Like chrome before it, and seemingly all electron apps, the .deb is not able to resolve all dependencies. In order to get slack working you must do the following.

1. Download the latest .deb from here
2. Try to install the .deb with dpkg

   cd ~/Downloads
   sudo dpkg -i slack-desktop-*-amd64.deb
   

   This step will fail with an error that looks like this:

   levlaz@ubuntu:~/Downloads$ sudo dpkg -i slack-desktop-2.1.2-amd64.deb
   Selecting previously unselected package slack-desktop.
   (Reading database ... 228971 files and directories currently installed.)
   Preparing to unpack slack-desktop-2.1.2-amd64.deb ...
   Unpacking slack-desktop (2.1.2) ...
   dpkg: dependency problems prevent configuration of slack-desktop:
   slack-desktop depends on libappindicator1; however:
   Package libappindicator1 is not installed.
   
   dpkg: error processing package slack-desktop (--install):
   dependency problems - leaving unconfigured
   Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...
   Processing triggers for desktop-file-utils (0.22-1ubuntu5) ...
   Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160701-0ubuntu1) ...
   Rebuilding /usr/share/applications/bamf-2.index...
   Processing triggers for mime-support (3.59ubuntu1) ...
   Errors were encountered while processing:
   slack-desktop
   

3. Once that step fails, install the required dependencies with

   sudo apt-get -f install
   

Now you can open Slack and chat away.