Objective 5.3 covers basic file permissions and ownership. I already have a guide covering this topic pretty well, so I will refer you to it. For understanding setuid and setgid programs, I wrote a guide demonstrating how they work. If you end up working with Linux professionally, you will need to understand file permissions very… Read More »
Linux setuid and setgid programs allow a regular user to alter the user or group it runs as. Below, I provide a program written in C to demonstrate the concepts. Don’t worry if you aren’t a programmer or have good grasp on C. I will walk you through how the program works. I am assuming… Read More »
Using a proxy with DNF is straightforward. You can edit /etc/dnf/dnf.conf, set the relevant environment variable, or use the shell sub command. DNF supports both HTTP and SOCKS proxies and several authentication methods. Keep in mind a few things when caching package repositories: Package repositories running on HTTPS cannot be cached without something like Squid’s… Read More »
Using a proxy with Curl is straightforward and flexible. There are a few methods you can use. You can specify the proxy URL on the command line, or set the appropriate environment variable. Using -x This is the most straightforward way to use a proxy server with curl. Using the -x option guarantees that you… Read More »
The curl command is a great tool with a lot of uses. When used for HTTP, it doesn’t follow redirects. However, following redirects with curl is easy. If you are in a hurry, the short answer is the -L option: $ curl http://tylersguides.com > tylersguides.html % Total % Received % Xferd Average Speed Time Time… Read More »
Linux Essentials Objective 5.2 is about creating users and groups. How you go about this depends on your system, but this section is written with the assumption that you are using local files. Just be aware that some systems can use things like Hesiod or LDAP to store login information. This topic can get pretty… Read More »
This objective is about navigating the filesystem through the command line. Unlike Windows systems, Linux systems don’t use drive letters. Instead, they use mount points. On a Linux system, the filesystem begins at /, known as the root directory, instead of the respective drive letter for the storage device or network share. You access the… Read More »
The easiest way to tell which shell you are using is by looking at what the exe link points to in your shell process’s /proc directory. You can use the command ls -l /proc/$$/exe. Below is an example: $ ls -l /proc/$$/exe lrwxrwxrwx 1 tyler tyler 0 Sep 22 19:39 /proc/19867/exe -> /bin/bash The special… Read More »
Listing all users on Linux is best done with the getent passwd command. This isn’t the only way, but it should work an practically any system. Unlike other methods, it uses your systems /etc/nsswitch.conf configuration to show users from all sources. The format is the format used in the file /etc/passwd. $ getent passwd root:x:0:0:root:/root:/bin/bash… Read More »
There are a few good reasons for setting up an HAProxy LDAP backend. Perhaps the client’s TLS implementation is lacking. Maybe the application only supports a single server and you can’t afford down time. In the latter scenario, setting up multiple address records in DNS with the same domain name. The problem with that is… Read More »