8 ms·

Everything you ever wanted to know about terminals (2018)

70 points by n3t 6y ago

msla 6y ago
ncurses is a lot more readable than just dropping raw control codes into your source code, and it works, whereas raw control codes might work and often don't.
deleted 6y ago
[deleted]
laksdjfkasljdf 6y ago
that site has great personal branding. recall seeing other articles from lexi halle on the feediverse some time ago and immediately recognized it. great content too.
kohtatsu 6y ago
I was just reading up an ANSI escape sequences a few days ago, this is gold. I adore the format and writing style too.
floatingatoll 6y ago
Previously: https://news.ycombinator.com/item?id=21601600 https://news.ycombinator.com/item?id=21601600 https://news.ycombinator.com/item?id=18125167 https://news.ycombinator.com/item?id=18125167
deleted 6y ago
[deleted]
theamk 6y ago
That’s pretty nasty - this article is factually incorrect in probably the worst way: the code will work on author’s computer, but not for other people [0] Not to mention that it is missing “good citizen” features like turning off colors when stdout is not a tty. [0] https://news.ycombinator.com/item?id=18125374 https://news.ycombinator.com/item?id=18125374
- inetknght 6y ago
  > “good citizen” features like turning off colors when stdout is not a tty. Better solution: do not detect whether your output is a tty or not. Let the user decide they want colors or not by using `--color=always` or `--color=never` or similar. There's few things worse than writing a script and getting different output just because you're no longer running the program interactively.
  - anitil 6y ago
    Gah i got bit by this with 'jq'! > $ echo "{}" | jq > {} > $ echo "{}" | jq > out.json > jq - commandline JSON processor [version 1.5-1-a5b5cbe] ... etc ... Turns out when stdout isn't a tty you _must_ specify a filter (in this case '.')
    - inetknght 6y ago
      Yup! I had the same problem too. It was 'fixed' in jq 1.6, such that it now assumes `.` is the filter if no program arguments are provided [0]. It happens all the time with anything systemd or networkmanager too [0]: https://github.com/stedolan/jq/releases/tag/jq-1.6 https://github.com/stedolan/jq/releases/tag/jq-1.6
    - deleted 6y ago
      [deleted]
  - theamk 6y ago
    I don't see how this is supposed to work? Let's take "grep" for example -- you want both of these to work, and print color to terminal: grep box file.txt grep box file.txt | grep -v orange-box Having --color=always is nice sometimes, but there is a reason grep has "--color=auto" and it is the default. If we write invisible characters to file, this breaks all sorts of tools, so it is much safer and more predictable to not include them.
    - inetknght 6y ago
      If I wanted to see just orange-box, then I would do grep --color=always orange-box file.txt But, I don't want to see just orange-box. I want to see orange-box and compare against other cases of box. So I would do: grep --color=always box file.txt | grep --color=always orange-box Without that --color=always, other cases of box will be drowned out by the noise. And if I wanted to write that out to a file then I would do grep --color=never orange-box file.txt > matches.txt Alternatively, I'd add a filter to the file with `ansi2txt` grep --color=always box file.txt | grep --color=always box | ansi2txt > no-color-matches.txt
miguelmota 6y ago
Can barely read the content with that colorscheme.
ablekh 6y ago
The lack of attention to (or, rather, the complete disregard of) proper capitalization is ridiculous. This is the second post I'm seeing in two days that feature this "style". Quite a disturbing trend, if you ask me.
- 8fGTBjZxBcHq 6y ago
  why is it disturbing it reads fine to me
  - ablekh 6y ago
    bEcAuSe pRoPer cApItAlIzAtIoN iS iMpOrTaNt fOr rEaDaBiLiTy ;-)
- brian_cloutier 6y ago
  What is ridiculous and disturbing about using lowercase letters at the beginning of your sentences? In a world where this trend continues your eye will become used to it and it will no longer be a distracting shock from what your eye is used to.
  - jjoonathan 6y ago
    In a world where everyone has terrible body odor, your nose will become used to it and it will no longer be a distracting shock.
    - brian_cloutier 6y ago
      This analogy doesn't hold. You were born with a sensitivity for body odor, you were not born with any sensitivity for lowercase letters. Do you really mean to imply that sentences which start with lowercase letters are intrinsically visually offensive?
      - jjoonathan 6y ago
        Every time I've given the benefit of the doubt to someone who opens our interaction by intentionally burning social capital on something frivolous, it has been a mistake.
titzer 6y ago
Oh man, they left out the part I was hoping to find out more about! > it's good form to have a function called resize() or similar that you run on program start and later when the terminal window is resized. while there is a horrible way to do this with ANSI escapes, it's better to just bite the bullet and learn how to use ioctls and termios. I wanted to know about the horrible ANSI escape sequences to send that can query the window size. Afaict one has to read from the terminal to get the answer--but these are control sequences that could be inserted into the normal stream--when, where, how?
- pherrephatta 6y ago
  You can look at the programmer's guide for the VT100[1], which does a good job of explaining the different ANSI escape codes. To put it simply, you can move the cursor down and to the right. For example, you'd move the cursor 999 lines down, then 999 columns to the right, and then query the cursor's position[2]. You can then read the output through STDOUT and parse it. I'd recommend anyone who's interested in playing around with ANSI and learning how to write a pure terminal-based program to look into the Kilo text editor[3]. That's where I learnt the above instructions. [1] https://vt100.net/docs/vt100-ug/chapter3.html https://vt100.net/docs/vt100-ug/chapter3.html [2] https://vt100.net/docs/vt100-ug/chapter3.html#CPR https://vt100.net/docs/vt100-ug/chapter3.html#CPR [3] https://viewsourcecode.org/snaptoken/kilo/ https://viewsourcecode.org/snaptoken/kilo/
- akira2501 6y ago
  Horrible escape sequences: man 4 console_codes Horrible console ioctls: man 4 console_ioctl
ximm 6y ago
I recently rewrote my fork of cplay and got fed up with curses. Boy do I wish I had found this article earlier because it describes everything I painfully had to cobble together. This is great! Just one nit: Doing stuff in a signal handler is usually a bad idea because it can interrupt your code at any time. The usual work around is a trick called "self-pipe". https://ldpreload.com/blog/signalfd-is-useless https://ldpreload.com/blog/signalfd-is-useless For anyone interested, I created a library in the process: https://github.com/xi/boon https://github.com/xi/boon (It takes some inspiration from react but bare with me, I think it actually makes sense.)
spicybright 6y ago
Interesting, but I wish it was less emotionally charged. But very cool using macros to make an easy styling "language"!
Chris2048 6y ago
What's this stuff about: > also, i'm a) a nobody and b) a woman. nothing i wrote would ever gain any traction; any project designed to supplant ncurses needs to come from someone who's actually known to the FOSS community. and a maintainer who isn't a cripple. Did ncurses gain popularity because of the identity of its maintainer(s)?! I was of the impression that it's whoever gets there first.

70 points by n3t 6y ago

msla 6y ago

ncurses is a lot more readable than just dropping raw control codes into your source code, and it works, whereas raw control codes might work and often don't.

deleted 6y ago

[deleted]

laksdjfkasljdf 6y ago

that site has great personal branding. recall seeing other articles from lexi halle on the feediverse some time ago and immediately recognized it. great content too.

kohtatsu 6y ago

I was just reading up an ANSI escape sequences a few days ago, this is gold. I adore the format and writing style too.

floatingatoll 6y ago

Previously: https://news.ycombinator.com/item?id=21601600 https://news.ycombinator.com/item?id=21601600 https://news.ycombinator.com/item?id=18125167 https://news.ycombinator.com/item?id=18125167

deleted 6y ago

[deleted]

theamk 6y ago

That’s pretty nasty - this article is factually incorrect in probably the worst way: the code will work on author’s computer, but not for other people [0] Not to mention that it is missing “good citizen” features like turning off colors when stdout is not a tty. [0] https://news.ycombinator.com/item?id=18125374 https://news.ycombinator.com/item?id=18125374

inetknght 6y ago
> “good citizen” features like turning off colors when stdout is not a tty. Better solution: do not detect whether your output is a tty or not. Let the user decide they want colors or not by using `--color=always` or `--color=never` or similar. There's few things worse than writing a script and getting different output just because you're no longer running the program interactively.
- anitil 6y ago
  Gah i got bit by this with 'jq'! > $ echo "{}" | jq > {} > $ echo "{}" | jq > out.json > jq - commandline JSON processor [version 1.5-1-a5b5cbe] ... etc ... Turns out when stdout isn't a tty you _must_ specify a filter (in this case '.')
  - inetknght 6y ago
    Yup! I had the same problem too. It was 'fixed' in jq 1.6, such that it now assumes `.` is the filter if no program arguments are provided [0]. It happens all the time with anything systemd or networkmanager too [0]: https://github.com/stedolan/jq/releases/tag/jq-1.6 https://github.com/stedolan/jq/releases/tag/jq-1.6
  - deleted 6y ago
    [deleted]
- theamk 6y ago
  I don't see how this is supposed to work? Let's take "grep" for example -- you want both of these to work, and print color to terminal: grep box file.txt grep box file.txt | grep -v orange-box Having --color=always is nice sometimes, but there is a reason grep has "--color=auto" and it is the default. If we write invisible characters to file, this breaks all sorts of tools, so it is much safer and more predictable to not include them.
  - inetknght 6y ago
    If I wanted to see just orange-box, then I would do grep --color=always orange-box file.txt But, I don't want to see just orange-box. I want to see orange-box and compare against other cases of box. So I would do: grep --color=always box file.txt | grep --color=always orange-box Without that --color=always, other cases of box will be drowned out by the noise. And if I wanted to write that out to a file then I would do grep --color=never orange-box file.txt > matches.txt Alternatively, I'd add a filter to the file with `ansi2txt` grep --color=always box file.txt | grep --color=always box | ansi2txt > no-color-matches.txt

miguelmota 6y ago

Can barely read the content with that colorscheme.

ablekh 6y ago

The lack of attention to (or, rather, the complete disregard of) proper capitalization is ridiculous. This is the second post I'm seeing in two days that feature this "style". Quite a disturbing trend, if you ask me.

8fGTBjZxBcHq 6y ago
why is it disturbing it reads fine to me
- ablekh 6y ago
  bEcAuSe pRoPer cApItAlIzAtIoN iS iMpOrTaNt fOr rEaDaBiLiTy ;-)
brian_cloutier 6y ago
What is ridiculous and disturbing about using lowercase letters at the beginning of your sentences? In a world where this trend continues your eye will become used to it and it will no longer be a distracting shock from what your eye is used to.
- jjoonathan 6y ago
  In a world where everyone has terrible body odor, your nose will become used to it and it will no longer be a distracting shock.
  - brian_cloutier 6y ago
    This analogy doesn't hold. You were born with a sensitivity for body odor, you were not born with any sensitivity for lowercase letters. Do you really mean to imply that sentences which start with lowercase letters are intrinsically visually offensive?
    - jjoonathan 6y ago
      Every time I've given the benefit of the doubt to someone who opens our interaction by intentionally burning social capital on something frivolous, it has been a mistake.

titzer 6y ago

Oh man, they left out the part I was hoping to find out more about! > it's good form to have a function called resize() or similar that you run on program start and later when the terminal window is resized. while there is a horrible way to do this with ANSI escapes, it's better to just bite the bullet and learn how to use ioctls and termios. I wanted to know about the horrible ANSI escape sequences to send that can query the window size. Afaict one has to read from the terminal to get the answer--but these are control sequences that could be inserted into the normal stream--when, where, how?

pherrephatta 6y ago
You can look at the programmer's guide for the VT100[1], which does a good job of explaining the different ANSI escape codes. To put it simply, you can move the cursor down and to the right. For example, you'd move the cursor 999 lines down, then 999 columns to the right, and then query the cursor's position[2]. You can then read the output through STDOUT and parse it. I'd recommend anyone who's interested in playing around with ANSI and learning how to write a pure terminal-based program to look into the Kilo text editor[3]. That's where I learnt the above instructions. [1] https://vt100.net/docs/vt100-ug/chapter3.html https://vt100.net/docs/vt100-ug/chapter3.html [2] https://vt100.net/docs/vt100-ug/chapter3.html#CPR https://vt100.net/docs/vt100-ug/chapter3.html#CPR [3] https://viewsourcecode.org/snaptoken/kilo/ https://viewsourcecode.org/snaptoken/kilo/
akira2501 6y ago
Horrible escape sequences: man 4 console_codes Horrible console ioctls: man 4 console_ioctl

ximm 6y ago

I recently rewrote my fork of cplay and got fed up with curses. Boy do I wish I had found this article earlier because it describes everything I painfully had to cobble together. This is great! Just one nit: Doing stuff in a signal handler is usually a bad idea because it can interrupt your code at any time. The usual work around is a trick called "self-pipe". https://ldpreload.com/blog/signalfd-is-useless https://ldpreload.com/blog/signalfd-is-useless For anyone interested, I created a library in the process: https://github.com/xi/boon https://github.com/xi/boon (It takes some inspiration from react but bare with me, I think it actually makes sense.)

spicybright 6y ago

Interesting, but I wish it was less emotionally charged. But very cool using macros to make an easy styling "language"!

Chris2048 6y ago

What's this stuff about: > also, i'm a) a nobody and b) a woman. nothing i wrote would ever gain any traction; any project designed to supplant ncurses needs to come from someone who's actually known to the FOSS community. and a maintainer who isn't a cripple. Did ncurses gain popularity because of the identity of its maintainer(s)?! I was of the impression that it's whoever gets there first.