How to Munin Graph JVM Memory Usage with Ubuntu tomcat

The following description works when using the Ubuntu "tomcat7" package:

Grab the "java/jstat__heap" plugin from munin-contrib @ github and place it into "/usr/share/munin/plugins/jstat__heap".

Link the plugin into /etc/munin/plugins

ln -s /usr/share/munin/plugins/jstat__heap /etc/munin/plugins/jstat_myname_heap

Choose some useful name instead of "myname". This allows to monitor multiple JVM setups.

Configure each link you created in for example a new plugin config file named "/etc/munin/plugin-conf.d/jstat" which should contain one section per JVM looking like this

[jstat_myname_heap]
user tomcat7
env.pidfilepath /var/run/tomcat7.pid
env.javahome /usr/

Liferea 1.10.7 Released

Today there is another maintenance release for 1.0 introducing a patch from Chris Siebenmann:

 * Make Liferea use ETags and send If-None-Match
   (patch by Chris Siebenmann)

Download Liferea 1.10.7

https://github.com/lwindolf/liferea/releases/download/v1.10.7/liferea-1.10.7.tar.bz2

Website Technology Changes in January 2014

As in the last four months I'm looking into changes visible at the frontend pages of the biggest websites. The last month saw a lot of version upgrades and hiding server versions.

The detailed results can be found here:

What Changed?

DNS-Prefetching The HTML header based DNS prefetching is expanding once more and for the first time used on adult site: xnxx.com
IPv6 An AAAA record was sigthed for the first time for yandex.ru
Version Upgrades
  • bildblog.de upgrades from Gentoo PHP 5.4.13 to 5.5.7
  • flipkart.com upgraded nginx 1.4.1 to 1.4.4
  • gomez.com switched OS and upgraded Apache 2.2.13 (Win32) to 2.2.15 (Red Hat)
  • jquery.com upgraded PHP 5.3.27 to 5.3.28
  • kickass.to upgraded Gentoo nginx 1.5.1 to bleeding edge 1.5.10 same for PHP 5.5.5 to 5.5.9
  • taz.de upgraded Apache 2.2.16 to 2.2.22
  • wetteronline.de upgraded Apache 2.4.2 to 2.4.7
  • xhamster.com upgraded nginx 1.4.1 to 1.4.4 and PHP 5.3.15 to 5.3.21
Hiding Server Version Additional sites are now hiding the webserver version

Note: the website links lead to a history page for the different sites were you can see the change details.

Caution!

All the results listed above are based on a simple scanning script. The results present a snapshot of the websites and a single response only. This is of course not necessarily an indicating for what techniques the site uses in daily operations!

Liferea 1.10.6 Released

Today saw the stable release 1.10.6. It provides two important bug fixes:

* Fixes SF #1135: liferea-add-feed doesn't process feed:https//
  (patch by Kevin Walke)
* Fixes SF #1137: crash on startup in enclosure_list_view_load
  (reported in Redhat #1048499, Fedora #214888)

Download Liferea 1.10.6

https://github.com/lwindolf/liferea/releases/download/v1.10.6/liferea-1.10.6.tar.gz

Sharing Screen With Multiple Users

How to detect screen sessions of other users:

screen -ls <user name>/

How to open screen to other users:

  1. Ctrl-A :multiuser on
  2. Ctrl-A :acladd <user to grant access>

Attach to other users screen session:

With session name

screen -x <user name>/<session name>

With PID and tty

screen -x <user name>/<pid>.<ptty>.<host>

Website Technology Changes in December 2013

As in the last three months I'm looking into changes visible at the frontend pages of the biggest websites. As to be expected changes during December are a bit limited as probably everyone favours stability over the holidays.

The detailed results can be found here:

What Changed?

DNS-Prefetching The HTML header based DNS prefetching is still there and gained yet another site: flipkart.com
IPv6 No change in AAAA records.
Version Upgrades fu-berlin.de upgrades from Apache 2.2.17 to 2.2.22
conduit.com upgrades from IIS 7.5 to 8.5
microsoft.com upgrades from IIS 8.0 to 8.5
Webserver Change Documentation site w3schools.com now shows nginx 1.2.6 instead IIS 7.5 as user facing webserver
Hiding Server Version One more site hostgator.com stopped reporting the Apache version

Note: the website links lead to a history page for the measurements.

Caution!

All the results listed above are based on a simple scanning script. The results present a snapshot of the websites and a single response only. This is of course not necessarily an indicating for what techniques the site uses in daily operations!

Liferea 1.8.16 and 1.10.5 Released

Today saw the release of 1.8.16 and 1.10.5. While 1.8.16 provides only a notification fix, 1.10.5 has those bug fixes:

* Fixes #1056, #1089, #1098: Honor preferences when opening links
  (patch by Daniel Seither)
* Fixes SF #1096: missing installation of liferea.convert file
  (reported by stqn) 
* Fixes Redhat #947358: popup notification only for new items
  (patch by Fabrice Bellet)

Changes in Release Notifications

Please note that starting now releases will be published on Github and the Sourceforge "News" feed is not in use anymore. Please unsubscribe this feed and subscribe to either

Download Releases

git Cheat Sheet

Create new git branch

Create a new git branch and switch to it

git checkout -b <new branch name>

and create it on origin too

git push origin <new branch name>

Remove git branch

Remove git branch locally with

git branch -d <branch name>

and remove on origin too

git branch -d -r origin/
git push origin :

Alternatively remove on origin and then prune locally.

Remove stale git branches

When remote branches disappear clean them from your local repo with

git remote prune origin

Rebasing a branch

To rebase on master

git rebase master <branch name>

Enable git password Caching

To keep passwords for 1h run

git config --global credential.helper 'cache --timeout=3600'

Amending changes

git add <files>
git commit --amend

How to apply patches with git

A detailed description can be found here. You should always run the following commands:

git apply --stat cool_feature.patch    # Check what the patch will do
git apply --check cool_feature.patch   # Check if the patch fails
git am --signoff < cool_feature.patch

Git - Tracking Remote Branches

To follow additional branches in your local repo follow these steps:

# Find out all existing remote branches
git branch -r

# And track one of them locally
git branch --set-upstream-to <branch> <remote/branch>

Git and Stashing Changes

For a detailed explanation check here. This feature is useful to put debugging or experimental changes to the "background". Here are the commands:

git stash "Some test I made"    # Stash some changes away

git stash list                  # List stashes
git stash show stash@{0}        # Show changes file in last stash
git stash show -p stash@{0}     # Show patch for last stash

git stash apply stash@{0}       # Get last stash active again
git stash drop stash@{0}        # Delete last stash

git stash pop                   # Apply and remove last stash

git stash clear                 # Delete all stashes

# Stash just some files by adding all others first 
# and using --keep-index
git add <all files you want to keep>
git stash --keep-index

Remove all repo files from a directory

If you ever need to remove all git related files from a local working repo and make it just a normal directory:

git clean -ffrx

List Commits in One Line Each

git rev-list --all --pretty=oneline

List Git Branch in Bash Prompt PS1

There are several documentations online e.g. this one. In the end it boils down to running "git branch" on each prompt and to use an environment function __git_ps1() that is set up by "git branch" to print the branch if there is one. So if your current $PS1 is

export PS1='\u@\h:\w\$ "

you could extend it to

export PS1='\u@\h:\w$(git branch &>/dev/null; echo $(__git_ps1 "(%s)"))\$ '

to show the branch name in braces after the directory name and before the $ like this:

john@server:~/project/src(master)$ 

Liferea 1.10 Schema Crash on Fedora 18/19

In case you want to self-compile Liferea 1.10 on Fedora and you find it crashing on startup with something like this

(liferea:3798): GLib-GIO-ERROR **: Settings schema 'net.sf.liferea' 
does not contain a key named 'last-node-selected'

please run

/usr/bin/glib-compile-schemas /usr/share/glib-2.0/schemas

It seems like the schema installation doesn't work properly on Fedora. This was reported and solved by nmdias in ticket SF #1093.

How to dry-run with chef-client

The answer is simple: do not "dry-run", do "why-run"!

chef-client --why-run
chef-client -W

And the output looks nicer when using "-Fmin"

chef-client -Fmin -W

As with all other automation tools, the dry-run mode is not very predictive. Still it might indicate some of the things that will happen.

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