Collection of cool things I learnt today.
Console fonts
Today I learned how to deal with console fonts To show current and all available fonts: showconsolefont ls /usr/share/kbd/consolefonts/ To set a font, or reset: setfont <font-name>
Today I learnt
Ruby symbols
Today I learned about symbols in ruby. Ruby strings are mutable unlike python strings (and C strings literals) They are allocated in the heap and can be changed over time. "Hello"[0] = 'h', exactly like [1,2,3][0] = 0 in python, is legitimate in ruby because strings are mutable, However :Hello[0] = "h" is not. Symbols are some sort of immutable strings, they are more efficient than strings because they are stored in the stack and they don’t change references. Symbols are used as key in hashes, in general when we value identiy over data. because they prevent reallocatng string every time. Ruby’s Symbols explained
Null values in Hibernate
Today I learned the difference between @NOT_NULL and @COLUMN (nullable=false). @NOT_NULL operates at the bean validation while @COLUMN is defined in the Persisatance API specs. https://www.baeldung.com/hibernate-notnull-vs-nullable
Qemu vs KVM
Today I learned the difference between Qemu and KVM. When working together, KVM arbitrates access to the CPU and memory, and QEMU emulates the hardware resources (hard disk, video, USB, etc.). When working alone, QEMU emulates both CPU and hardware. source
Difference between common filesystems
Today I learned about the filesystems popular in linux, and the diffenrence between them. BTRFS vs EXT4 EXT4 is a pure Filesystem, comes with basic fs functionalities including journaling, while BTRFS has more additional features like Snapshots, Checksums, encryption and compression. The main difference though is that BTRFS is COW (copy on Write) fs. which means it does not overwrite a file when modified, instead it make a copy and deal with it. COW make BTRFS not relying on a journal file and make snapshots easier. ...
Newsboat separators
Today I learned that lines in the urls file with raw text, i.e not a RSS links, are added to the feeds’ list as ther are. I used this to add separators to my own feed, and divide it to sections.
Query params vs path var
Today I learned the terminology path variables and query parameters, what they are and what is the difference between them. You can lean more here Here.