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Top Forums Shell Programming and Scripting Grepping for hex characters - explanation? Post 302491099 by DGPickett on Wednesday 26th of January 2011 05:17:22 PM
Old 01-26-2011
My take is the $ is literal, but regex keep morphing under my feet:

Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns

I usually just use the tab key or ctrl-V ctrl-whatever, in ' ', or $(echo a|tr 'a' '\027') (but my tr only does octal). But I use ksh, this is a bash-ism:
Code:
$ bash <<!
echo $'\x61'
!
a
$


Last edited by DGPickett; 01-26-2011 at 06:32 PM..
 

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readkey(3alleg4)						  Allegro manual						  readkey(3alleg4)

NAME
readkey - Returns the next character from the keyboard buffer. Allegro game programming library. SYNOPSIS
#include <allegro.h> int readkey(); DESCRIPTION
Returns the next character from the keyboard buffer, in ASCII format. If the buffer is empty, it waits until a key is pressed. You can see if there are queued keypresses with keypressed(). The low byte of the return value contains the ASCII code of the key, and the high byte the scancode. The scancode remains the same whatever the state of the shift, ctrl and alt keys, while the ASCII code is affected by shift and ctrl in the normal way (shift changes case, ctrl+letter gives the position of that letter in the alphabet, eg. ctrl+A = 1, ctrl+B = 2, etc). Pressing alt+key returns only the scan- code, with a zero ASCII code in the low byte. For example: int val; ... val = readkey(); if ((val & 0xff) == 'd') /* by ASCII code */ allegro_message("You pressed 'd' "); if ((val >> 8) == KEY_SPACE) /* by scancode */ allegro_message("You pressed Space "); if ((val & 0xff) == 3) /* ctrl+letter */ allegro_message("You pressed Control+C "); if (val == (KEY_X << 8)) /* alt+letter */ allegro_message("You pressed Alt+X "); This function cannot return character values greater than 255. If you need to read Unicode input, use ureadkey() instead. SEE ALSO
install_keyboard(3alleg4), ureadkey(3alleg4), keypressed(3alleg4), clear_keybuf(3alleg4), simulate_keypress(3alleg4) Allegro version 4.4.2 readkey(3alleg4)
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