Category: bash

Determine which Tomcat version is running

Determine process id

First we determine the process id(s) of the running Tomcat instance(s).

We can grep the running process list for ‘catalina.home’:

pgrep -f 'catalina.home'

This might yield more than one pid.

Or we can search by port (8080 is the default, adjust if necessary). The following commands will likely require root privileges:

lsof -t -i :8080

Alternatively, for example if lsof is not installed:

fuser 8080/tcp

Or yet another way, using netstat (or its “ss” replacement):

netstat -nlp | grep 8080

ss -nlp | grep 8080

Determine catalina.home

For the process id(s) determined above, we look at process details:

ps -o pid,uid,cmd -p [pidlist] | cat

For each specified pid, this shows the uid (system user) and the full command line of the process.

Typically the command line will contain something like “-Dcatalina.home=[path]” and that path is the catalina.home system property of the Java process.

Alternatively – with Java 7 and later – we can use the JDK command “jcmd” to query the JVM process for its system properties:

sudo -u [uid] jcmd [pid] VM.system_properties \
   | grep '^catalina.home' \
   | cut -f2 -d'='

Determine version

Now we can finally determine which Tomcat version is installed under the catalina.home path:

[catalina.home]/bin/catalina.sh version \
   | grep '^Server number:'

Note: Please replace [catalina.home] with the path you determined above.

The final output should be something like this:

Server number: 7.0.56.0

Retrieve “last modified” timestamp of web resource in UTC seconds

This command line assumes that “${url}” is the URL of the web resource:

curl -s -I "${url}" | grep 'Last-Modified:' | cut -c 16- | date -f - +'%s'

It can be useful to check the freshness of a download URL before a GET request.

You could compare the result to the last-modified timestamp of a local file and only download the remote file if it is newer than the existing local one.

Compare two Tomcat installations using rsync

Lets assume you manage multiple servers that host Java web applications using the Tomcat web server.

To quickly compare the Tomcat installations on host1 and host2, we can use the “dry-run” mode of the rsync command.

In the following example, we assume that you have ssh access to both of your Tomcat hosts, the installations are in /opt/tomcat and the “tomcat” system user has read access to all relevant files and directories of the installation:

ssh tomcat@host1
rsync --archive --checksum --dry-run --verbose --delete \
      --exclude temp --exclude work --exclude logs --exclude webapps \
      /opt/tomcat/ tomcat@host2:/opt/tomcat/

This will list

  • All files that differ in checksum
  • All files that only exist on host2 (look for ‘deleting [filename]’)

Run the same commands with host1 and host2 switched, to also see the files that only exist on host1.

We excluded the temp, work and logs directories because they are variable in nature.
We also excluded the webapps directory because we only wanted to compare the base installation.

Spotify on Debian GNU/Linux in Canada

Today I decided to try out the free ad-sponsored Spotify music streaming service. It has been available in Canada since September 2014.

After signing up you can immediately use the flash-based web player at play.spotify.com.

Installing the client app

Alternatively you can download and install the Spotify client app. I cannot say yet what the advantages or disadvantages are, maybe reading this article can be helpful.

Anyway, if you want to try the client app, for Debian (or Ubuntu) users it works like this:

  1. Add the repo key (to verify downloaded packages)
  2. Add the spotify repo to apt sources
  3. Update apt caches
  4. Install the spotify client

Here are the shell commands (requires sudo):

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys BBEBDCB318AD50EC6865090613B00F1FD2C19886
echo deb http://repository.spotify.com stable non-free | sudo tee /etc/apt/sources.list.d/spotify.list
sudo apt-get update
sudo apt-get install spotify-client

After successful installation you will find a “Spotify” entry in the “Multimedia” section of your start menu.

Using your Facebook login

If you use your Facebook account to sign into Spotify you will probably see this question:

Spotify would like to post to Facebook for you.
Who do you want to share these posts with?

It is safe to choose “Not Now” which prevents Spotify from posting to your timeline. The login will still work.

If your are using the downloaded stand-alone client app and the Facebook login fails with an error page, then simply enter the email address and password from your Facebook account into the login fields of the Spotify client app.

Spotify says that it only uses these credentials to pass through to the Facebook authentication and won’t store your password anywhere. I hope that’s true.

Set the X cursor theme in XFCE 4.10

After upgrading to Debian Jessie and XFCE 4.10, I set the default cursor theme in XFCE main menu – Settings – Mouse and Touchpad – Theme tab.

But this seemed to affect only a few applications.

To consistently set the theme for all applications and the desktop I had to run this:

oliver@debian:~$ sudo update-alternatives --config x-cursor-theme
There are 3 choices for the alternative x-cursor-theme (providing /usr/share/icons/default/index.theme).

  Selection    Path                                    Priority   Status
------------------------------------------------------------
  0            /usr/share/icons/Adwaita/cursor.theme     90        auto mode
  1            /usr/share/icons/Adwaita/cursor.theme     90        manual mode
  2            /usr/share/icons/DMZ-Black/cursor.theme   30        manual mode
* 3            /usr/share/icons/DMZ-White/cursor.theme   50        manual mode

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

Select the desired theme from the listed options and make sure it is the same as the one you selected in the XFCE settings.

Fix Eclipse installation after Cygwin unzip

I used Cygwin’s unzip on Windows 7 to unpack freshly downloaded Eclipse zip packages. When trying to start eclipse.exe, I was getting weird error messages:

For Luna (4.4):

eclipse-luna-error-after-cygwin-unzip

For Mars (4.5):

eclipse-mars-error-after-cygwin-unzip

It turned out that after unzipping, the executable permission was not set on ‘exe’ and ‘dll’ files, so I had to fix it like this:

find eclipse \( -name '*.dll' -or -name '*.exe' \) -exec chmod +x {} \;

How to use Oracle Java 8 plugin in Iceweasel on Debian wheezy

Download the JRE from Oracle website.

Then perform the following steps (adjust the tar.gz filename according to what you downloaded, and replace “jre1.8.0_40” with the directory of your extracted tar.gz):

cd /opt
sudo tar xvzf ~/Downloads/jre-8u40-linux-x64.tar.gz
sudo chown -R root.root jre1.8.0_40
sudo ln -s jre1.8.0_40 jre
sudo update-alternatives --install /usr/lib/mozilla/plugins/libjavaplugin.so mozilla-javaplugin.so /opt/jre/lib/amd64/libnpjp2.so 1000
sudo update-alternatives --set mozilla-javaplugin.so /opt/jre/lib/amd64/libnpjp2.so

Using sipgate.de on Linux with Linphone SIP client

Note: This is a follow-up blog entry to yesterday’s post about using the Zoiper SIP client on Linux. Linphone works comparably well so far and if I won’t come across any issues, I will recommend Linphone, since it is fully Open Source, which future-proofs is existence and allows others to contribute and improve the software better than for a closed-source product like Zoiper.

Linphone is a GPL licensed SIP client (“softphone”). It has been around since 2001 and is actively developed by the French company Belledonne Communications.

As the name suggests, the software was first developed for Linux but has gradually become truly cross-platform, now supporting Windows, MacOS, Linux, Android, iOS, Windows Phone 8 and most recently a web edition. For most operating systems, simply visit linphone.org and follow the download and installation steps indicated there.

Users of GNU/Linux distributions like Debian, Ubuntu, etc, install the distribution package through their favorite package manager. On my Debian stable (“wheezy”) I did this today:

sudo apt-get install linphone

Then I started up Linphone from the XFCE Start menu, where it is listed in the “Internet” submenu. I canceled the account setup wizard because it didn’t seem to work for me, disabled Video in the Options menu because I am not planning to use it yet, then selected Options – Preferences – Manage SIP accounts and configured my sipgate.de account like this:

Your SIP identity: sip:3998984@sipgate.de
SIP Proxy address: sip:sipgate.de

Screenshot

linphone-sipgate-account

Note that “3998984” is my sipgate.de SIP account name, so you have to substitute it with yours, but note that it is usually not the same as your sipgate.de web login username.

After this initial setup, I successfully tested the account and my headset by calling the sipgate.de test number 10005, which works very similarly to the Skype test call feature.

For personalized config information you can log in at sipgate.de and consult the “Konfigurationshilfe“, selecting one of the Linphone entries from the softphone device lists. I have a sipgate.de basic account, so if you are on a different plan, details may vary slightly.

If this blog post was helpful and/or if something seems inaccurate, please leave a comment. Happy telephoning …

Build Java Maven github project on travis-ci

Update 14/Aug/2018: I no longer use an FTP space for the build artifacts, instead I use bintray.

I used to use Cloudbees’ buildhive for continuous builds of my Java/Maven based github projects. But buildhive currently does not offer JDK 8. So far that hasn’t been a problem, but I recently started using lambdas and default methods in interfaces and other Java 8 goodness. And now buildhive does not work for me anymore.

So I looked for alternatives and tried travis-ci.org. It was easy enough to set up a free account: You just authorize their service through your github login. Then all your projects will be listed on travis and you just click a switch to enable a build.

.travis.yml with FTP upload

To actually activate a build, you have to add a .travis.yml file at the root of your project.

The builds then happen automatically whenever you commit changes to github. This is the build list for one of my projects.

My build produces a distributable zip file, using Maven assembly plugin, that contains all the jars and start scripts of my application. I want to make the latest stable version of that zip file available for public download. With buildhive I used the permanent URL of the build artifact within the workspace of the last stable Jenkins build. But travis does not store anything after the build.

To make travis-ci build artifacts available, a deploy step is required. Many cloud storage systems are supported, but I opted for a custom deploy via FTP to my web space at dev.doepner.net.

So to build my Java Maven project with JDK 8 and do the FTP upload of the zip artifact, I ended up with these lines:

language: java
jdk: oraclejdk8

env:
  global:
  - secure: L2lr/F0gIvyVUl0nJ7w9saGV7wZkL6nO61IxilDY/76iTlnhrFXn5Q8vATGbiRYdDW/tG1kyDUbKaWSkYrpV2Agm4wV/KmMg2CWRiIcQPPqwSEENx/1UZ/dBnCQGcRkkYApu5ayjGnX3Srg3ty1zvdud/O8tiKtWkkBDipJSpfY=
  - secure: OekVM5ZyLGHpqurOUWJcq0kKBA78WKZdXaA9aylwrjjQFeVoZxyxeZTYbhLajN4Ggg4Th58QwjUHpwcgZlnsxx4heDo1wyHxXojJd0H1LWKXJwet82IXaFJbl+Yz/htr7uWSFTUF6Szx70cpMxlGe3qsIFlgViEo9UGhHHdrjdY=

after_success:
  ./.travis/artifact-upload.sh

The env – global – secure entries are the encrypted username and password for my FTP server. Details about the encryption steps are at the end of this blog post.

Artifact upload script

The .travis/artifact-upload.sh script performs the actual upload. The .travis directory is in the root of my github project. The script looks like this:

#! /bin/bash

local_file="$(ls $TRAVIS_BUILD_DIR/typepad-dist/target/*.zip | head -n 1)"
target_url='ftp://doepner.net/~/public_html/dev/dist/ci-builds/typepad.zip'

echo "Uploading $local_file to $target_url"
curl -u $FTP_USER:$FTP_PASSWORD -T "$local_file" "$target_url"

I am only interested in the latest zip and I want the URL to be permanent, that’s why the filename is hardcoded as typepad.zip.

Build status and download links

Similar to buildhive, travis-ci provides nice build status icons that automatically show the current status of your build.

The README.adoc of my github project now contains these build status and download links:

== Build status

image:https://travis-ci.org/odoepner/typepad.svg?branch=master[
link="https://travis-ci.org/odoepner/typepad"]

http://dev.doepner.net/dist/ci-builds/typepad.zip[Download latest build]

If you are not used to this syntax: It is AsciiDoc, not the default Markdown format of github READMEs.

Encryption of FTP credentials

Travis supports encryption of environment variables. This makes sense, because you probably don’t want to expose your FTP username/password to the world.

To perform the encryption, a local travis command-line installation is required. On Debian it can be setup like this:

1) Install JRuby (but not Rails)
2) gem install travis
3) cd to local working copy of your project
4) travis encrypt FTP_USER=yourusername --add
5) travis encrypt FTP_PASSWORD=yourpassword --add

The --add tells the travis command to add the resulting config directly to the .travis.yml file in your project directory. That’s why you first need cd to the base dir of your project.