How does ls set the color of the text

[justin]

When you open a C source file with nano and redirect the output to a text file, you can see the escape sequences used to set the color. If you do the same with ls you get only the directory listing with no escape sequences.

How does ls change the text color?

[NickJohnson]

Magic.

Also, a program can tell if stdout is a tty, using isatty(). But it's probably the magic.

[justin]

Magic.

Also, a program can tell if stdout is a tty, using isatty(). But it's probably the magic.

Is there a way I can see the raw output that the tty sees?

[Love4Boobies]

What does any of this have to do with OS development?

[justin]

What does any of this have to do with OS development?

How does it not have to do with OS development? Does your OS not have a console?

I want to learn about ways to handle colored text.

[VolTeK]

The function printing has to have a parameter or a certain character representation in the string you pass to it, to determine if it wants to be changed to a certain color. Actually changing the colors though..

Is definitely in the wiki, i haven't checked, but i'm damn well certain they are.

[roboman]

You can google 'escape sequence change text color' or wait a week or two until I finish my video driver for DexOS

[NickJohnson]

What does any of this have to do with OS development?

How does it not have to do with OS development? Does your OS not have a console?

I want to learn about ways to handle colored text.

ls uses escape sequences to color its text just like any other program. You would make more progress looking up documentation on terminal emulators than trying to reverse engineer ls.

[Combuster]

Also, a program can tell if stdout is a tty, using isatty(). But it's probably the magic.

Is there a way I can see the raw output that the tty sees?

Terminal emulation

[XanClic]

Magic.

Also, a program can tell if stdout is a tty, using isatty(). But it's probably the magic.

Is there a way I can see the raw output that the tty sees?

If it's only about a colored ls…

Code: Select all

ls --color=always | less

[amd64pager]

It is in this format:

Code: Select all

#include<stdio.h>
printf("\033[%d;%dm%s\033[0m\n",color,color + 30,string);

string contains your string to be printed in your colour and color can be these values:

• 0 - black
  1 - red
  2 - green
  3 - yellow
  4 - blue
  5 - magenta
  6 - cyan
  7 - white

Try it out.

[justin]

If it's only about a colored ls…

Code: Select all

ls --color=always | less

Thanks. This is exactly what I wanted to see.