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Cake day: June 17th, 2023

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  • Remove the loop and sleep from the script you created so it just runs and exits.

    Then create a file at /etc/systemd/system/battery-alarm.service with the following:

    [Unit]
    Description="Sound alarm when battery is low"
    
    [Service]
    ExecStart=/usr/local/bin/battery-alarm.sh # point this to your script
    

    Then create a file at /etc/systemd/system/battery-alarm.timer with the following:

    [Unit]
    Description="Run battery-alarm.service every 2 mins"
    
    [Timer]
    OnUnitActiveSec=2m
    Unit=battery-alarm.service
    
    [Install]
    WantedBy=multi-user.target
    

    Then sudo systemctl enable --now helloworld.timer to start and enable the timer on boot.

    This will be a little more robust then your current script. It works without the user needing to log in. And there is nothing to get killed so will always trigger. The current script will just silently stop working if it ever gets killed or crashes.


  • Worth running shell scripts though https://www.shellcheck.net/ (has a cli as well). Finds lots of common issues that can blow up scripts when input is not what you expect. With links to why they make the suggestions they do.

    Line 4:
            battery_level=`cat /sys/class/power_supply/BAT0/capacity`
                          ^-- SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
    
    Did you mean: (apply this, apply all SC2006)
            battery_level=$(cat /sys/class/power_supply/BAT0/capacity)
     
    Line 5:
            battery_status=`cat /sys/class/power_supply/BAT0/status`
                           ^-- SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
    
    Did you mean: (apply this, apply all SC2006)
            battery_status=$(cat /sys/class/power_supply/BAT0/status)
     
    Line 6:
            if [ $battery_status = "Discharging" ] && [ $battery_level -lt 21 ];
                 ^-- SC2086 (info): Double quote to prevent globbing and word splitting.
                                                        ^-- SC2086 (info): Double quote to prevent globbing and word splitting.
    
    Did you mean: (apply this, apply all SC2086)
            if [ "$battery_status" = "Discharging" ] && [ "$battery_level" -lt 21 ];
    



  • Or your example, how would we have processed ore into metal without coal (on any significant scale).

    We have been processing ore into metal with coal for thousands of years. It sounds like you are arguing that the industrial revolution has been happening for thousands of years. Which it has not.

    We also made bread in the industrial revolution which is needed to feed the workers. Without feeding the workforce we could not access certain advancements. Is bread a corner stone technology of the industrial revolution? No it is not. It in no way defines what the industrial revolution was. Just like coal or oil.

    You can run a steam engine off of coal, wood, oil, nuclear, basically anything that creates a lot of heat. Coal is more convenient in a lot of ways but it did not unlock anything special. If not for coal we could use wood or charcoal. That was the steam engine, not the fuel it runs on.

    And if the advancements were because of these fuels that why did it not happen 1000s of years ago when we had access to them?









  • A water central heating system is a closed loop system that is under pressure. This means the water in it is circulated around and around the system and is cut off from other water supplies under normal operation. Naturally, slow leaks happen and gas can enter the system in various ways so occasionally this needs to be released from the system. Any gas in the system naturally collects at the highest points along the path - which tend to be the radiators.

    When you bleed a radiator you are opening the system to the outside and hopefully where the gas has accumulated. Since the system is under pressure it forces the gas out of the system to equalize the pressure with the outside. This will cause the pressure of the system to drop and eventually it will stop.

    However there should be a control valve somewhere, typically on/near the boiler that connects the central heating system up to the mains water supply. You can open this valve to cause water to flow into the central heating system and pressurize it and really this should be done every time you bleed the radiator a significant amount.

    In apartments though you might find that you are on a building wide circuit, or you might have one isolated for your apartment. If you have a boiler in your apartment then you are likely on a closed system and should be able to equalize the pressure yourself. If it is building wide you need to talk with your building manager.

    Note that you should not need to bleed your radiators that often. Once every several years should be more than enough. If you are doing it frequently then you likely have a large leak in your system and likely want to get someone to check that out.


  • REPLs are basically shells. They behave the same way in every essential way. So the real question is support vs non-supported shells. But then that is easy - non supported shells fall back to just what a normal commands do ATM to process input/output. Other applications like TUIs are also easy to deal with as they already enter a different mode called raw mode - when a application requests that it can do what they currently do - switch to a new buffer and give full control to that one application.

    I can’t think of any, but I’m not the most creative person… what do you have in mind?

    Having smarter scroll back that knows the difference between a prompt/command and the output would let you do quite a few things that would be nice to have. Such as collapsing the output so you can only see the commands, keeping the command at the top of the screen even as other output scrolls off the top so you can always see what was running. Extra support for other UI elements could be nice to have as well - like tooltip support for blocks or similar.

    All the shell - or really any application - needs to do is tell the terminal which bits of the output are witch. Like mark the start/end of the prompt, command and command output. Then the fallback is basically ignore the markers and print things out like it currently does.

    And those are just random thoughts I have had over the last few days. These can be implemented in backwards compatible ways I believe and don’t need special support for specific shells - just needs to expand the VT100 protocols to be able to send more information between the terminal and shells/applications that are running. Much like how color, cursor positioning, entering/exiting raw mode etc are already done. Though I think some tight specialized integration might be a good start to explore these ideas before the protocols are formed.


  • What I would love to see is a terminal that builds it’s own shell from scratch too rejecting the ancient ideas we have with bash. I still love bash but I’m curious what could come of it.

    Thinking about it some more I am not sure that we would have to go that far. Well not in the longer term - short term we might for experimenting with ideas. I think one of the bigger problems ATM is the terminal does not understand what a shell is or its component parts. Terminals just display characters and move the cursor around the screen and send keyboard and now mouse input back to the command they run. They are also aware of alternative buffers and raw input mode and know about echoing characters back the the screen.

    If we extended the terminals to also understand some shell concepts like the prompt, commands being typed and output from the commands and gave the shell some markers it could send along with these (like we do with color information ATM) the terminal would be able to use these to change how it displays each part and would open up a lot of new an interesting features. Could even add things like tooltip support or actions on clicking some bits of the text.

    I am starting to see these terminals as experimenting on what we features could be enabled if we were not stuck on the current VT100 protocals. Though if we ever get wider adoption and generalisation of these ideas backed back into the protocals will be another question to consider.


  • Thinking about it some more I don’t think we would need to abandon the whole TTY to get a good set of the features. What is basically required for a lot of the features is more communication between the shell and the terminal. There is already some communication for basic things - like raw mode and alternative buffers, colors and even images. These are how TUI programs like vim or screen/tmux function and how you can exit them without losing what was previously in the buffer.

    I wonder if markers for the prompt and start/end of command output would probably enable a lot smarter virtual terminals with only some minor additions to the VT100 protocols. Possibly some extra data could be sent as well - like optional tooltip data maybe or even supporting actions that when the user clicks something it can send a response back to the shell. Maybe like a retry button on previous commands for example.

    There is quite a lot that could be done if the terminal and shells had better protocals to communicate between each other. I dont think these will change overnight though so seeing terminal emulators try out these features to find what people like/want to use IMO is a good thing to see where we can take things in the longer term.

    Would we have to abandon SSH or always X forward

    No we would not. At the end of the day a TTY is just a input and output pipe between the terminal and the program running on the shell with a specific protocal VT100 (or some bastardized version of that - looking at you xterm). This is what network protocals are as well - just with different protocals in play. So you can do a lot over that connection with changes to the protocals. No need for xforwarding at all.


  • nous@programming.devtoLinux@lemmy.mlNew terminal apps: Warp and Wave
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    21 days ago

    Might I add the idea that your terminal emulator must support your shell is utterly ridiculous?

    TBH I am starting to come around to the idea of a tightly integrated shell and terminal emulator support. There are just things you cannot do with these being separate things. I am very tempted to explore the idea from the other end though - writing a shell that has a emulator built into it (like screen/tmux basically are). But I do think that this integration is needed for any per command features that is not just printing out a prompt.

    It would be interesting to see what could be done with this type of integration but will likely break support for existing shells. Unless you maybe launch a shell for each command you run or something 🤔. Would like to seem more people experimenting with stuff like this and see what new things we could drive forward. We have been stuck with the current tty system since like the 80s to support devices that just dont exist anymore.


  • nous@programming.devtoLinux@lemmy.mlNew terminal apps: Warp and Wave
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    21 days ago

    I think the issue fundamentally is that this isn’t what terminal emulators are. The terminal emulator initializes a TTY session and enters a shell environment (sh, zsh, fish, etc). The medium is text and cannot be anything else.

    This is 90s thinking. Why must terminal emulators only be text and only do things that a physical terminal could? What makes teminals so nice is not that they work on 90s technology. Some terminal emualtors can already display images. Which is great. And the ideas they are introducing are still fundamentally text based, but are geared towards structuring that texts a bit more than a constant stream of characters on the screen.

    Skill issue. Pipe your output to something (like a file or the “less” command)

    This is a convenience issue not a skill issue. Yes you can pipe output to things but you need to know before hand that you want to do that. And with less you lose that output once you close less. And with files you have to clean them up after the fact. Both of these are inconvenient and need to be thought of before you run a command. IMO it would be nice to just run a command and then be able to collapse or expand or search its output after the fact and not have to preempt everything beforehand.

    The argument that you can already do that in a much less convenient way is not a very good argument.