Linux stores users’ encrypted passwords, as well as other security information, such as account or password expiration values, in the /etc/shadow file.
Someday you may need to edit the /etc/shadow file manually to set or change ones password. (more…)
If you try to upgrade salt-minions from the salt-master, in most cases salt-master would probably lose access to the minions.
If the access is lost, you would have to log in to each host and restart the salt-minion service manually to make it communicate back with the salt-master.
This problem is caused by the salt-minion service that often doesn’t restart after update. (more…)
In salt, there is a useful file.managed state that can download files over HTTP/HTTPS and save them on the target system.
Unfortunately for the moment it is not possible to download a file using salt in an normal way without knowing the file’s hash.
If you try to download a file using salt state without source_hash, salt will fail with “Unable to determine upstream hash of source file” error. (more…)
Git is a version control system (VCS) that allows to keep track of the changes made to a project over time.
Git records the changes you make to a project, stores those changes and then allows you to reference them as needed.
From the following article you will learn what does the basic Git workflow consist of and the simple Git commands for everyday use. (more…)
Sometimes it is required to merge several PDF files into a one PDF file.
In Linux we can easily join multiple PDF files using the command line utility called convert that is a part of ImageMagick software suite.
From this article you will learn how to merge entire PDF files into one PDF file or how to join specific PDF pages only into a single PDF file. (more…)
The mod_wsgi is an Apache module that provides a WSGI compliant interface and serves for hosting Python based web applications under Apache (for example Django).
To find out which version of mod_wsgi is installed or compiled, it is required to create a simple WSGI application.
From the following article you will learn how to create and run on Apache a simple WSGI application that prints the version of mod_wsgi. (more…)
The mod_wsgi serves for hosting Python based web applications under Apache.
This short article describes how to create a basic WSGI application and run it on Apache using mod_wsgi.
Below you would find how to create a virtual host in Apache and publish a simple WSGI application that just prints “Hello World!”. (more…)
Apache has a lot of modules (or “mods”) that extend its core functionality for special purposes.
How to list installed Apache modules – is a common question as it is very often required to check which Apache modules are loaded/enabled.
List of installed Apache modules can be found using special option for httpd/apachectl (CentOS, RHEL etc.) or apache2/apache2ctl (Ubuntu, Debian etc.) commands. (more…)
Telnet is a tool for connecting to servers on a given port for troubleshooting connection issues.
One of the most common tasks that you can do via telnet – is connect to some web server and verify its health by checking the response code in HTTP header.
Or you can get the content of a whole web page via telnet if you need to analyze it deeper. (more…)
Lets say you have been working on a project that is tracked by Git and suddenly realized that you did something wrong.
You have some not yet committed changes and you want to undo everything.
In particular you want to delete all newly created files and folders and restore all modified or deleted.
In short you need to revert all changes back to the last commit. (more…)