Author Archives: ronaldpringadi

Auto Login Using SSH Public and Private Keys

2026 update: This post originally used ssh-keygen -t rsa. The current recommendation (e.g. GitHub’s SSH key guide) is Ed25519 — it produces shorter keys, is faster, and is considered more secure. Use RSA (4096-bit) only as a fallback for systems … Continue reading

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Linux symlinks: creating, deleting, and the gotchas worth knowing

The basic command for creating a symbolic link (a “symlink” or “soft link”) to a folder or file is ln -s: 12345678ln -s /home/ronald/somefolder /home/ronald/newfolder # or if your current directory is already /home/ronald: cd /home/ronald ln -s somefolder newfolder … Continue reading

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A Linux primer: identifying your distro and other commands that work everywhere

Here are a few commands you can use to find out which Linux distribution you’re on — pick whichever your system has: 1234567cat /etc/issue cat /proc/version dmesg | head -1 cat /etc/*-release Of those, cat /etc/*-release is the most reliable … Continue reading

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How to Set up an FTP Server in Ubuntu Linux

Login to your Linux shell menu as root 12[root@locahost]# apt-get install vsftpd [root@locahost]# vim /etc/vsftpd.conf At VIM, 1st comment out anonymous_enable by adding a # sign at the beginning of the line # anonymous_enable=YES 2nd remove comment at local enable … Continue reading

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Adding color to your tail

Tail is a very useful tool for monitoring an error stream. Sometimes the output from tail can have too much information, and its black-and-white monotone output can be hard to follow with the eyes. The basic: a Linux terminal has … Continue reading

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JSON Jumpstart

123456789101112131415161718192021222324252627282930313233343536373839404142434445/**  * In JSON, curly brackets mark a new object ({ or })  * Any variable inside the object — also known as the object’s attribute — is  * accessible using the dot syntax (object.attribute) or the bracket syntax  * … Continue reading

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Vodafone Group, AT&T, and Verizon are The Biggest Yielding Companies In November 2011

Vodafone Group, the telecom giant known for its land line and wireless services around the U.S and U.K, together with two other U.S based telecom giants AT&T and Verizon are one of the best yielding companies in Nov 2011. As … Continue reading

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Biggest Companies in the USA (Top 30)

If you ever get interested with the top 30 biggest companies in the USA you can visit this link: http://www.greenandredmarket.com/menu/biggestcompanies.htm I’m really surprised that Apple‘s Market Capitalization is almost twice bigger than Microsoft

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An nmap primer: scanning ports, fingerprinting hosts, and staying legal

If you just want a quick look at what’s listening on a Linux machine, the one-liner is: 1nmap -sS -O 127.0.0.1 That’s an nmap SYN scan with OS detection against your own loopback interface. If you’ve never used nmap before, … Continue reading

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Find Files in Linux by Name

To find files in Linux with a certain name portion or pattern we can issue a locate command. If locate is unable to find a matching file, then you might need to update your file index database. 12# locate journal-2011-07 … Continue reading

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