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Full Discussion: While loop and IFS?
Top Forums Shell Programming and Scripting While loop and IFS? Post 302519298 by sid22 on Tuesday 3rd of May 2011 03:25:27 PM
Old 05-03-2011
While loop and IFS?

Hi,
Code:
while [ 1 -eq 1 ]; do
    echo "Please enter "
    read enter
    yyyy=${enter:0:4}
    mm=${enter:5:2}
    dd=${enter:8:2}
    result=`validateDate $yyyy $mm $dd`

When does the loop keeping repeating till?? till 1 is equal to 1?

what does this mean "${enter:0:4}" .The 0 and 4 part??

What does IFS do?? so if its set to IFS='' . What happens?? or what can you do with it??

Last edited by Scott; 05-03-2011 at 04:32 PM.. Reason: Code tags
 

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keyboard_translatekeys(3)					Svgalib User Manual					 keyboard_translatekeys(3)

NAME
keyboard_translatekeys - modify scancode mappings in raw keyboard mode SYNOPSIS
#include <vgakeyboard.h> void keyboard_translatekeys(int mask); DESCRIPTION
This function sets several flags which control how certain scancodes are mapped. At startup a mask value of 0 is active. mask must be a logical or of zero or more of the following #predefined integers to turn the features listed on: TRANSLATE_CURSORKEYS Translate the scancodes of the SCANCODE_CURSORBLOCK* keys to those of the cursor keys on the number pad, s.t. keyboard_getstate(3) and keyboard_keypressed(3) report a keypress of the corresponding number pad cursor key and not the one on the cursor block. TRANSLATE_DIAGONAL Translates the scancodes of diagonal cursor keys (keypad 7, 9, 1, 3) to presses of two of the ordinary up, down, left, right keys. For example, instead of reporting a press of SCANCODE_CURSORUPRIGHT keyboard_getstate(3) and keyboard_keypressed(3) report a simul- taneous press of SCANCODE_CURSORUP and SCANCODE_CURSORRIGHT. TRANSLATE_KEYPADENTER The scancode of the keypad enter key is mapped to that of the ordinary enter key, s.t. keyboard_getstate(3) and keyboard_key- pressed(3) report a press of SCANCODE_ENTER regardless if keypad enter or ordinary enter is pressed. DONT_CATCH_CTRLC Pressing <Ctrl>-C does not raise a SIGINT. On contrary to the other flags this has also effect when a user defined keyboard event handler is used. Svgalib will always process <Alt>-F1 - <Alt>-F10 and perform console switches accordingly. BUGS
The TRANSLATE_* options above do really do simple scancode translations. For example, when TRANSLATE_KEYPADENTER is active and the user presses both enter and keypad enter. Then, if he releases one of them (say keypad enter), it's release event will clear the common keyboard state, s.t. no keypress is reported even though enter is still pressed. Similarly, if TRANSLATE_DIAGONAL is active, the user holds cursor upleft (keypad 7) down and then presses and release cursor up (keypad 8), svgalib will only report a pressed cursor left but the simulated cursor up will be lost. You can easily try this with the keytest(6) demo to make the effect more clear to you. SEE ALSO
svgalib(7), vgagl(7), libvga.config(5), keytest(6), eventtest(6), keyboard_seteventhandler(3), keyboard_init(3), key- board_init_return_fd(3), keyboard_close(3), keyboard_update(3), keyboard_waitforupdate(3), keyboard_setdefaulteventhandler(3), key- board_getstate(3), keyboard_clearstate(3), keyboard_keypressed(3), vga_waitevent(3) AUTHOR
This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the referenced function as well as of the original documentation is unknown. It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>. Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual. Svgalib (>;= 1.2.11) 29 July 1997 keyboard_translatekeys(3)
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