Find files and file content on the terminal can be achieved by the use of the find tool.

By far one of the best tools is „Silversearcher ag“, install it with sudo apt-get install silversearcher-ag. If you want to search for example recursive all folders, only php files for the search string „my Value“, simply type:

Find file/s containing a specific string in its name:

Now list all files that contain the word „searchTerm“

List all the occurrence and their respective line-number of „searchTerm“ in files. The parameter -n toggles the line-number, the parameter -H toggles the filename.

Do you want to list all files bigger than size x? Here we go:

A handy tool as well is ack-grep (you have to install it first). Be sure to wrap the search-term in single quotes.


crontab is a mighty linux tool intendet for executing tasks schedule by predefined timing rules.

List all schedules of current user

List all schedules of specific user


You’d like to exchange data – files or folders – from a local machine to a remote one or visa verce?
scp (secure copy) is the tool of choice.

Copy local file to remote folder

Copy local folder to remote folder

Copy remote file to local folder

Copy remote folder to local folder



Disable Browser cache for firefox:

type in the url-bar:

confirm the warning. and set browser.cache.disk.enable and browser.cache.memory.enable both to false


Disable Browser cache in chrome

press F12 (open the developer-toolbar), go to Network and uncheck „Disable cache“.
The cache is only disabled while the developer-toolbar is open!!!

Unfortunately Debian (Jessie) didn’t recognized my WiFi hardware during os installation. So I had to mess with the installation by myself. Well, what have i done so far?

First I figured out with iwconfig if there was a driver installed…

No there wasn’t, cause the result was simply

I missed something like wlan0. Before you know what driver you need to install, you need to figure out which hardware you have. That can be done with the following command:

You receive a large list with lots of information you don’t need. The art is, to find out what is your wifi chip, and there is no general purpose solution, cause different computers might have different hardware. In my case I looked for words like „wifi“, „wireless“, „communication“ and so on. Anyway, the entry I was looking for was this one:

I picked the chipname:

and searched in google, to verify if it was really a wifi chip. H-node is a good source for hardware reseach.

Finally i found here: that my chipset was supported.

I extendet /etc/apt/sources.list with the following line:

and performed another two commands:

The following command first removes the iwlwifi module from the limux kernel and then adds it to the kernel.

Now everything should work fine, and you should find in the network-settings your wifi hotspot.

Veröffentlicht unter Debian.

Representational State Transfer

REST is a paradigma for data transfer between client and server. It’s using the verbs GET, POST, PUT, DELETE (and some others) from the HTTP-protokoll,
hence there is almost everywhere a solid infrastructure. For Machine-2-Machine communication REST is a smart choice.

REST deals with resources uniquely identified by URL’s. For Example: could be a user ressource with 5 as an user id. By requesting this resource via different types of HTTP verbs typical CRUD (create, read, update, delete) actions can be performed on the ressource.

I will show some very simple ways how to get startet with REST.

Imagine you would call a REST service with curl from the commandline like this (thats a GET request):

or with a POST request:

The responding server-side could look somewhat like this.
We deal here with pseude-code. Depending on the framework you use, it differs how to access parameters passed alongside the request.


Veröffentlicht unter REST.

CURL is a mighty tool for transfering data to URLS. It supports a wide range of protocols.

Lets have a closer look on some handy snippets for daily work on the commandline:

Fetching content from a URL

When a page redirects to another location (the respondet http-status is somewhat 3xx)
curl can follow the redirection with the -L (- -location) flag.

Want to see what the request and response headers like?
It’s as simple as using the -v (- -verbose) flag.

For POSTing data to an URL u can use the parameter -d (- -data) .

You want to upload a file (image.jpg is located in the folder from where you run this command) to a php-script running at localhost/upload.php:

a upload-script for taking the uploaded file and store it in a file – the filename is the current timestamp – looks like this:

This is for windows using the cmd. Parsing a folder recursively for all pdf files and send them as a POST request to a certain URI:


Introduction – learn some words

This explanations are meant for Linux-Systems. Well, before we dive into ssh, its time to learn some vocabulary. Let’s learn some common files related to ssh issues. Usually, you have a folder ~/.ssh in your home directory (the Tilde „~“ before the .ssh directory is a shell replacement for your home directory). Here you can find files like:

this file contains all the public keys you own from others. Compare the format of the content inside authorized_keys and compare it with the format of your key

id_rsa and
after creating a keypair (ssh-keygen) you get a private-key (which is by default stored in ~/.ssh/id_rsa) and a public-key (which lives in ~/.ssh/ Your private-key is for you alone, your public-key goes public. Private keys can have no extension but also have a .pem extension. There are also .ppk private-keys, these are created from the windows-ssh tool putty. A private key looks somethoing like:

whereas a public key looks like:

here are all servers stored that had already an established connection before.

with the file ~/.ssh/config you have a very handy config place to make ssh logins much easier. Check „man ssh_config“ for further information. If the config file does not exist you simply can create it.
Push your public-key to a server you want to communicate with:


Lets practice some commands


check details for a https certified website from the shell:


OpenSSL is a open-source version of the SSL/TLS-protocol

create a private key, a certificate signature request and a self signed certificate
create server.key

create .pem file

create server.csr (certificate signature request)

create unsigned certificate for 1 year


check if private-key fits to a certificate
you need to compare the hash-value of the certificate against the hash-value of the private-key

get the certificates hash-value

get the private-keys hash-value


remove passphrase from private key


rename certificate postfix cer to crt
you can just rename the file

Veröffentlicht unter ssh.

ImageMagic is the tool of choice when you have to manipulate images on the command line.


You can easily install it from a shell with the following command:

Change all images in the current folder to a with of 800 pixels with a quality of 80%:

Convert a *.gif image to a *.jpg image