In this config you will learn how to block or redirect web traffic based on the visitor’s country geographical location using Apache’s geoip mod.
Assuming that you already have Apache webserver installed and running we start by the installation of mod_geoip:
UBUNTU/DEBIAN # apt-get install libapache2-mod-geoip CENTOS/REDHAT/FEDORA ( epel enabled only ) # yum install mod_geoip.x86_64
Using an ENTRYPOINT Docker command specified within a Dockerfile one can pass an arguments to an interactive Docker container upon its launch. Consider a following Dockerfile content:
FROM debian:8 ENTRYPOINT ["echo"]
Below is a quick config on how to to encrypt and decrypt large files using OpenSSL and Linux such as Redhat, Ubuntu, Debian, CentOS, Fedora etc. First, what you will need is a some sort of arbitrary file. Let’s create 1GB file now:
$ fallocate -l 1G large_file.img $ ls -lh large_file.img -rw-r--r--. 1 lrendek lrendek 1.0G Jan 2 16:40 large_file.img
The nc ( netcat ) command can be used to transfer arbitrary data over the network. It represents a quick way for Linux administrators to transfer data without the need for an additional data transfer services such as FTP, HTTP, SCP etc. This config will show you an example on how to transfer data between to network hosts. We will be transferring data myfile.txt file from a localhost to a destination host with an IP address 10.1.1.2.
The nc command first needs to be started on the network host to which we need to transfer data. We will instruct nc to listen for an incoming request on user defined port number and once the client request comes receive the desired data. Pick the port number of your choice to ensure that it is not blocked by firewall and it is accessible from the source host.
$ nc -l -p 7555 > myfile.txt
The following linux commands will help you to obtain the information about your laptop battery such as manufacturer, part type, capacity, voltage etc. First, tool which can be used for this job is dmidecode command. If you currently do not have dmidecode available on your Linux system you can install it by:
UBUNTU/DEBIAN # apt-get install dmidecode CENTOS/FEDORA # yum install dmidecode
next, using dmidecode we can obtain some hardware information about our battery:
# dmidecode -t 22
# dmidecode 2.12
SMBIOS 2.6 present.
Handle 0x002E, DMI type 22, 26 bytes
Portable Battery
Location: Rear
Manufacturer: LGC
Name: 42T4942
Design Capacity: 93240 mWh
Design Voltage: 11100 mV
SBDS Version: 03.01
Maximum Error: Unknown
SBDS Serial Number: 073C
SBDS Manufacture Date: 2012-03-23
SBDS Chemistry: LION
OEM-specific Information: 0x00000000
In this config you can learn how to convert documents format between LibreOffice and Microsoft Office file formats on Linux. The preferred tool to use for a file format conversion between LibreOffice and Microsoft Office is unoconv. Let’s start with the installation of unoconv package:
FEDORA/REDHAT/CENTOS # yum install unoconv DEBIAN/UBUNTU # apt-get install unoconv
and create some LibreOffice document document.odt and spreadsheet spreadsheet.ods to play with:
$ file document.odt document.odt: OpenDocument Text $ file spreadsheet.ods spreadsheet.ods: OpenDocument Spreadsheet
Amazon currently accepts limited number of ebook formats that you can directly send to your Amazon Kindle. In this config we are going to show few Linux tools which may assist you with the conversion between various Document and eBook formats.
Based on your amazon Kindle type the supported formats may include:
The first tool you might consider is ebook-convert. This tool is available on Fedora , CentOS, Redhat Linux under the package named ebook-tools. To install ebook-tools package run the command below:
# yum install ebook-tools
Questions:
How can I remove all docker containers based on a docker image name. I do not wish to remove all available containers, only the those which are based on particular image. For example I would like to remove all containers based on image centos:7.
Answer:
To remove all docker containers based on centos:7 run the following linux command:
# docker ps -a | awk '{ print $1,$2 }' | grep centos:7 | awk '{print $1 }' | xargs -I {} docker rm {}