every so often I get confused because I'm writing a zine about the terminal and didn't I already write 4 zines about the terminal???
but I've never written about what the UI “rules” you need to know to use the terminal interactively are, only:
- notes on core Unix concepts — file descriptors, signals, etc (Bite Size Linux)
- shell scripting (Bite Size Bash)
- cheat sheets for sed/grep/xargs/etc (Bite Size Command Line)
- cheat sheets for command line networking tools (Bite Size Networking)
I haven't totally sold myself yet on this "what are the secret rules of the terminal?” framing but it feels like a reasonable way to talk about how, even though “the terminal” is a lot of separate things working together, it "feels" like a cohesive environment that has a lot of rules that you can generally expect to be true.
Some of those rules are Unchangeable Facts and some of them are just Vague Social Rules but understanding the vague social rules is just as important as knowing The Facts.
an example of a "social rule" in the terminal is that if you have a noninteractive program, you can generally expect that `Ctrl-C` will stop it, programs can do whatever they want but it would just be kind of rude for a noninteractive program to not respect `Ctrl-C`
(there are different and more complicated social expectations around how to quit interactive programs)
another example of a "social rule" is that at an interactive prompt you should expect `Ctrl-W` to delete the last word, this is weird because depending on the _kind_ of program, the exact mechanism for how `Ctrl-W` will delete the last word might change, but I think it would be generally considered rude if a program with an interactive prompt treated `Ctrl-W` in a different way
(text editors are an exception though and generally are allowed to handle text editing however they please)
another social rule is that if a program is writing its stdout to a file or pipe, it's expected to turn off colour codes so that users don't end up looking at output like this:
ESC[1;33massets.jsESC[0m
(as far as I know there is almost nothing enforcing this behaviour except that users will be unhappy if you don't do it)
i forgot to put “please don’t explain how terminal keybindings work to me” on this thread and i’m regretting it, anyway, please don’t, i wrote 4000 words about it if anyone wants a deep dive
https://jvns.ca/blog/2024/10/31/ascii-control-characters/
Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
I think that each time I write a script, I have to decide all over again whether to accept a single keystroke or to accept a whole line of input.
AFAIK, there's no consensus on that.
I’m convinced that if powershell had been born anywhere but Microsoft it would have replaced bash entirely by now. Even structured data is thin gruel compared to pipelines passing structures objects.
@itamarst @petrillic @mhoye @b0rk
https://www.nushell.sh to save someone else some clicks. I’m definitely going to take a look at this.
I’m not sure if I found the right lumin? https://lumin.readthedocs.io/en/stable/
@b0rk it's not a social role, it's necessary to not break pipes. For example
echo this is the way | grep the | grep 'the way'
If the middle grep outputs ansi codes to colorize "the" to make it stand out, the last grep will not match and therefore output nothing.
@The0x539 Interesting. Don't know anything about it (yet!).
Can you spoof if by eg just piping to `cat`, or to `tee /dev/null` or something?
@dan In unix and c it's the isatty() function. Usually you'd call that on stdout.
https://man.archlinux.org/man/isatty.3.en
Most other platforms and languages probably have something similar. For instance, when I duckduckgo "python isatty", "rust isatty", "golang isatty", "java isatty", or "js isatty", I find an example within the first couple hits.
Hope that helps!
@b0rk readline and its many assorted clones use Emacs bindings by default, as does Bash (perhaps Bash uses readline?). e.g. Ctrl-a goes to the beginning of the line, Ctrl-e goes to the end, Meta-b goes to the beginning of the current word, etc.
Ctrl-w is a weird one because in Emacs this means "kill" (analogous to "cut") and usually you have to have some text selected for it to do anything useful. In some implementations, Ctrl-y (Emacs' "yank") will paste back what you killed.
@dwenius @b0rk It's still a standard Linux pty behavior, and it doesn't look like default shell or terminal configurations disable the stop and start characters, either in eg gnome-terminal or in a console text login. I use it periodically to freeze program output so I can scan it before too much scrolls by.
(Did I just boot a VM and then fire up a KVM over IP interface just to check for sure? Yep, yep I did. I felt I couldn't trust my own desktop environment or ssh from it.)
@b0rk ah! yeah! we think you're absolutely right to call this a social rule
along with the whole success is silent, failure is noisy thing
and the use of ^D to exit from prompt-like interactions
and probably other stuff we're forgetting
Julia Evans
zellyn
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Irenes (many)man intro as somebody's long-ago proposed list of topics beginners should know, please consider this our recommendation to give that a look, too
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