Thomas 'Toke' Kerpe

Git Branch in bash prompt

2012-03-27T00:00:00+02:00

Git-Tipp

My Bash prompt is something like this archimedes:toke.de(master) toke$. Where archimedes is the hostname, toke.de the directory within an git checkout, master the actual branch and toke my username. To get this result set this PS1 in your .bashrc:

## Add Git-Branch
PS1='\h:\W$(__git_ps1 "(%s)") \u\$ '

Unix permission pitfalls #1

2012-03-05T00:00:00+01:00

Unix permission pitfalls #1

Let’s do an experiment:

$ mkdir test
$ cd test
$ mkdir abc
$ sudo chown -R root:root abc
$ ls -lsa abc
total 8
4 drwxr-xr-x  2 root   root   4096 2012-03-05 10:03 .
4 drwxr-xr-x 10 user   user   4096 2012-03-05 10:03 ..

Ok, that’s clear we created an empty directory and changed the ownership to root. Now to something destructive:

$ rm -rf abc
$ ls abc
ls: cannot access abc: No such file or directory

Hoops? Why could the user delete this directory?

Explanation

The reason we can delete root owned files and (empty) directories in our case is because the write of our delete is done in our freshly created directory “test” - which is owned - by us. You can think of an unix directory like an special file which contains the directory information of the containing elements. If we can write to the containing directory we can delete its contents.

Postgre password in psql

2012-02-28T00:00:00+01:00

Store a password for use in psql

I was asked today how to use store an password for use with psql. I’ve done this before several times but could not remember how. So I tried to look it up with man psql. There was a referer to .pgpass but no syntax. The pgpass is part of libpq. So this is a reminder to myself:

.pgpass format

hostname:port:database:username:password

To quote the Documentation: “Each of the first four fields may be a literal value, or *, which matches anything.”

Evaluating Disqus (updated)

2012-02-21T00:00:00+01:00

Commenting

I’m not a big fan of external services. Especially since I do not log IP-Adresses and offloading Javascript gives some more problems with privacy. This site is very simple. But I want to add comments to blog posts. My plan was to write a little comment script for embedding via Javascript. Since I don’t have so much time right now I will look for alternatives. Now I am experimenting with disqus. The service looks nice and integrates very well with my site. One downside is the missing SSL support. I will look after this later.

For the next weeks the disqus service will be available on this site, maybe for a longer time. We’ll see. Feel free to comment.

Update (22.04.2012)

Disqus seems to work with SSL now. I’ve enabled it. Hope this will stay alive.

How do I Post

2012-02-09T00:00:00+01:00

Or how this site is updated

This site is build via jekyll and the sources are coming from a git repository on github. I do not write something special about git or jekyll here. Just how the “deployment” works.

Github webhook

Github has a nice feature called “Service hooks” - especially a “Post-Receive URLs” hook. I use this hook to notify my server to do a git pull on a local repository, then rebuild the site with jekyll and rsync changed data to the document root.

The perl webhook endpoint (Dancer.pm code):

    package ReceiveHook;
    use Dancer ':syntax';
    
    our $VERSION = '0.3';
    
    # Configuration for different projects
    my $config = {
        "PROJECTNAME" => {
            run => "/home/user/bin/updateblog.sh",
        },
    };
    
    prefix '/notify';
    
    get '/*' => sub {
        header 'Allow' => 'POST';
        status '405';
        "Not for you\n";
    };
    
    post '/:project' => sub {
        if (not defined $config->{params->{project}}) {
            status 'not_found';
            return "No such project: ".params->{project}."\n";
        }
    
        my $payload = params->{'payload'};
        if (not defined $payload) {
            status '415';
            return "I need a payload\n";
        }
    
        # Read the configuration for that repo
        my $repo_config = $config->{$repo->{name}};
        if (defined $repo_config && defined $repo_config->{run}) {
            eval {
                system $repo_config->{run};
            };
        }
    
        return "OK";
    };
    
    true;

The update itself is done by this little shellscript:

    #!/bin/sh

    REPPATH="/home/user/git/localgitrepository"
    DEPLOYTARGET="/var/www/sites/mydomain"
    LIVEURL="http://mydeploydomain.tld"

    if [ -d ${REPPATH} ] ; then
        cd "${REPPATH}"
        git pull
        jekyll --url "${LIVEURL}"
        rsync -rXogpEAt _site/ "${DEPLOYTARGET}"
    fi

Code

Github repository feel free to use it as you like.

Hello world

2011-08-17T00:00:00+02:00

Hello from Jekyll

First post from jekyll.