Simple Samba Configuration for Public Shares

The Aim

Some­times it is nec­es­sary to share files from a POSIX oper­at­ing sys­tem (Lin­ux, FreeB­SD, etc.) with Win­dows com­put­ers via the net­work. For this task Sam­ba is the pow­er­ful inter­op­er­abil­i­ty suite which can han­dle this task. To dis­tin­guish between these two sys­tems I will dif­fer­en­ti­ate between POSIX (that is the sam­ba serv­er) and Win­dows computers.

Read More

Writing a Parser Is Boring?

When inter­act­ing with dif­fer­ent ser­vices or pro­gram there often comes the point where some sort of file has to be parsed into a data struc­ture, which can be processed lat­er. For stan­dard file for­mats like XML or JSON parsers are avail­able for almost any lan­guage out there. (BTW I love the graph­i­cal rep­re­sen­ta­tion of the JSON syn­tax on their website.)

There are how­ev­er sit­u­a­tions in which one has to deal with a pro­pri­etary file for­mat or with ven­dor-spe­cif­ic exten­sions to a stan­dard­ized for­mat. At this point a pars­er has to be writ­ten. It seems a bor­ing task, how­ev­er there are sev­er­al impor­tant aspects of pro­gram­ming which can be learned here.

Read More

Dancing the DHCP Samba

After a hard­ware fail­ure of a Lin­ux com­put­er I took the chance to set up a Debian instal­la­tion from scratch. So I saved the data that was impor­tant to a serv­er, burned the Debian DVD and installed it on the computer.

When it came to net­work­ing it got a lit­tle more com­pli­cat­ed: as the serv­er is using the cor­po­rate net­work, it had to send a spe­cif­ic host name to obtain the IP con­fig­u­ra­tion via DHCP. So that was what I did: I entered the host name and let dhcp­client do its mag­ic. It took some time, but final­ly it was set up. All DNS entries for this host name and its cor­re­spond­ing IP were correct.

Read More

Solarized — A Balanced Color Scheme for Text Editors

Col­ors schemes for text edi­tors is just like the favorite edi­tor itself a con­tro­ver­sial­ly dis­cussed and often very per­son­al mat­ter. Speak­ing about col­ors often the per­son­al taste is the main rea­son for a cus­tom col­or scheme or why a spe­cial scheme was cho­sen. How­ev­er the rela­tion between dif­fer­ent col­ors has been stud­ied by artists for a very long time. Col­or the­o­ry with things like the tri­ad, tetrad or com­ple­men­tary col­ors which was all relat­ed to the col­or cir­cle has been the foun­da­tion design­ers worked on a dai­ly basis.

Now these prin­ci­ples have been applied to col­or schemes in text edi­tors. The arrange­ment of col­ors is called Solar­ized and can be found on the pro­jec­t’s home­page. Besides the col­or scheme itself, which is avail­able for a wide range of edi­tors, start­ing from VIM, Emacs to Net­beans, Xcode, SubEthaEd­it or text­mate, the author Ethan Schoonover also explains the prin­ci­ples of why the col­ors were cho­sen that way. The scheme is avail­able in two vari­ants: one for a light back­ground and one for a black background.

What I like about this scheme is how the a good con­trast between fore­ground and back­ground is giv­en with­out over­do­ing it. You can cre­ate the largest con­trast by using a white text col­or on a black back­ground. This how­ev­er would tire your eyes very quick­ly, as the con­trast is too high. Solar­ized in the dark back­ground vari­ant is using a dark grey as a back­ground col­or and a very light grey as the text col­or. What I also like is that if syn­tax high­light­ing is acti­vat­ed com­ment blocks are shad­ed in a dark­er ver­sion of the text col­or to make your code more promi­nent which is great in heav­i­ly com­ment­ed files.

So if you are look­ing for a new col­or scheme for your favorite edi­tor or IDE, check out Solar­ized.

Backing up a Server to Amazon S3


When deploy­ing a serv­er on the inter­net you always have to deal with secu­ri­ty issues. You hard­en your serv­er by set­ting up encrypt­ed con­nec­tions, con­fig­ur­ing a tight fire­wall and putting crit­i­cal ser­vices in a chroot jail. How­ev­er what hap­pens if an intrud­er hacks into your serv­er and deletes your con­tent? Or if you make a mis­take and erase some data? The last line of defense is hav­ing a good back­up strategy.

The ques­tion aris­es what do back­up and where to back it up. For me some­thing like to holy grail would be hav­ing a fast, reli­able, file-sys­tem-based back­up solu­tion like the snap­shot fea­ture in ZFS. It should then be pos­si­ble to sync these snap­shots in a band­width-effi­cient man­ner to a remote location.

Using Duplicity for Backup

There are a lot of dif­fer­ent solu­tions around, how­ev­er they dif­fer in secu­ri­ty, price and reli­a­bil­i­ty. Duplic­i­ty is one of them. It is rel­a­tive­ly easy to set up if you have a sim­ple back­up prob­lem, such as back­ing up the web serv­er and its cor­re­spond­ing data­base. The neat thing about Duplic­i­ty is that it can make encrypt­ed, incre­men­tal back­ups using stan­dard file for­mats. For the incre­men­tal part of this oper­a­tion it relies on rdiff to do the heavy lift­ing and it is using GPG to encrypt the back­up with a public/private key pair. One of the oth­er ben­e­fits is that Duplic­i­ty offers out of the box Ama­zon S3 sup­port. This means that you are able to store your back­ups up in the cloud in a save man­ner. By per­form­ing incre­men­tal back­ups only, the costs for traf­fic and stor­age are min­i­mized. In my case which is per­form­ing a dai­ly back­up of the con­fig­u­ra­tion and the blog of the serv­er I nev­er paid any­thing because there is a min­i­mum billing amount per month.

Using a file serv­er in the cloud as the back­up des­ti­na­tion has its ben­e­fits espe­cial­ly in the restore case. Then you can rely on Ama­zon’s band­width to per­form a fast restore instead of using your home cable or DSL connection.

What is happening during a backup?

In the begin­ning, when there are no pre­vi­ous back­ups to be used for incre­men­tal back­ups, Duplic­i­ty is per­form­ing a full back­up. For its back­up files it uses stan­dard tar file for­mat which then gets encrypt­ed using GPG and your pub­lic key. It is then uploaded to a remote server.

The next back­up is an incre­men­tal back­up. This means that duplic­i­ty now first checks if its local cache of pre­vi­ous diffs is up to date with the remote repos­i­to­ry. If that is not the case it down­loads all the pre­vi­ous diffs because it needs them to gen­er­ate the new diff of the most recent changes. It then cal­cu­lates the diff, encrypts it and uploads it togeth­er with a hash of the diff to the remote server.

Backup a Database

When using a web appli­ca­tion often there are not only files, but also data­bas­es to be backed up to be able to ful­ly restore your web page from the back­up. In my case I am using a MySQL serv­er. The way I am doing it is first per­form­ing a mysql­dump and then back­ing this file up. I have writ­ten a small helper script in perl that is kicked off by a cron job.

I use for quite a while now and it is work­ing very nice­ly. As a start­ing point I pub­lished the back­up wrap­per script on github.

DTerm — A Terminal at Your Fingertips for Mac OS X

Some­times it would be great if one could just enter a com­mand in the ter­mi­nal which is relat­ed to the direc­to­ry of the file you are work­ing on: send it to a serv­er via scp, build a tar.gz archive, com­pile it or open anoth­er file. These are all oper­a­tions which have also a graph­i­cal “nice” way of exe­cut­ing it, but leav­ing your hands on the key­board can be so much faster.

The tool, which pro­vides a sys­tem-wide access to the ter­mi­nal is DTerm. It has been around for some time, as it has been released in 2008, but it was men­tioned recent­ly in the very nice mobileMac pod­cast (ger­man) I like a lot. The appli­ca­tion is free.

So what is it all about? With DTerm you define a hotkey (stan­dard is Com­mand-Shift-Return), which will over­lay a win­dow with a text field which accepts ter­mi­nal com­mands. They will be exe­cut­ed in the same direc­to­ry as your front­most appli­ca­tion. DTerm is use­ful if you for exam­ple would like to open anoth­er doc­u­ment in the same fold­er: just press DTer­m’s hotkey, enter open then the begin­ning of the file and press the tab­u­la­tor key to show a com­ple­tion list of all the files in the direc­to­ry. Choose the file and press enter and it is opened with its asso­ci­at­ed appli­ca­tion. Anoth­er use­ful short­cut is open . which opens the cur­rent direc­to­ry in the Find­er. If you are famil­iar with a ter­mi­nal on a *NIX based sys­tem now is the time to use all of your ter­mi­nal hacks every­where in your work­flow with­out touch­ing the Ter­mi­nal application.



DTerm home­page

New Highlighting Support in PasteBinIt

There is a new beta of Paste­BinIt avail­able with a nice fea­ture: high­light­ing sup­port. This means that you can click in the line num­ber gut­ter of the code view to set a mark­er that will show up in the paste­bin as a yel­low marked line

In addi­tion some UI tweaks have been made such as list­ing the 5 most recent syn­tax high­light­ings at the top of the menu.

Get the update here or use the inte­grat­ed updater if you have already down­loaded ver­sion 0.2–2.

Getting started

Hav­ing my serv­er up and run­ning, Word­Press installed in a way I like it, I am get­ting start­ed with my new web page.

Until now noth­ing inter­est­ing can be found here, how­ev­er after find­ing and adapt­ing the right theme for me I will be blog­ging about tech­ni­cal stuff and my pro­gram­ming projects here.

Hope you will enjoy it.