It often happens that I get into a situation
where I need to know key codes of pressed
keys. On my Mac that’s simple. Just use the
Key Codes by Many Tricks.
But on Linux I constantly was trying to find out which key produced what.
So I ended up writing a program for that. I started of in the shell, but that ended up being rather tricky and unnecessary complicated. So I redid the whole thing in C.
This is the result
/*
* Program : code.c
* Author : Ton Kersten
*/
#include <stdio.h>
#include <curses.h>
#define DONE 'q'
#define ESC 0x1b
#define SPC 0x20
char ch;
main()
{
printf("Press '%c' to quit!\n\n", DONE);
/*
* Put the terminal in raw mode, with no echo
*/
system("stty raw -echo");
/*
* Print the header
*/
printf("%4s\t%4s\t%4s\t%4s\r\n", "Char", " Hex", " Oct", " Dec");
printf("%4s\t%4s\t%4s\t%4s\r\n", "----", "----", "----", "----");
/*
* Set the initial loop value to something odd
*/
ch: DONE-1;
while ( ch != DONE )
{ ch: getchar();
/*
* Character read. Display it. Look out for < 0x20
*/
if ( ch < SPC )
{ if ( ch == ESC )
{ /*
* Esc. Just say 'Esc'
*/
printf("%-4s\t0x%02x\t%04o\t%04d\r\n",
"Esc", ch, ch, ch);
}
else
{ /*
* < ' '. Print Control character
*/
printf("^%-c\t0x%02x\t%04o\t%04d\r\n",
ch-1+'A', ch, ch, ch);
}
}
else
{ /*
* Normal character. Display it normally
*/
printf("%-4c\t0x%02x\t%04o\t%04d\r\n",
ch, ch, ch, ch);
}
}
/*
* Put the terminal back to something usefull
*/
system("stty sane echo");
}
And this is an example of the output
Press 'q' to quit!
Char Hex Oct Dec
---- ---- ---- ----
Esc 0x1b 0033 0027
O 0x4f 0117 0079
P 0x50 0120 0080
Esc 0x1b 0033 0027
[ 0x5b 0133 0091
2 0x32 0062 0050
4 0x34 0064 0052
~ 0x7e 0176 0126
q 0x71 0161 0113