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Full Discussion: how to test for backspace
Top Forums UNIX for Dummies Questions & Answers how to test for backspace Post 302398182 by karthigayan on Wednesday 24th of February 2010 02:23:30 AM
Old 02-24-2010
MySQL Use ASCII

There is no straight forward way to compare the backspace.But there are some other way like ,converting the character to ascii value and compare that with particular ascii value of the backspace.

ascii value of the backspace is 8.But when I print the ascii value of backspace in my system it prints 127.it is the ascii value of DEL.So I used 127 in my code.You just change that value to 8 if needed.

Code:
read -n 1 x
x=`echo $x | tr -d "\n" | od -An -t dC`
if [ $x  -eq 127 ]; then # Change the 127 to 8 if it need
echo "backspace detected"
else
echo "some other character"
fi

Thanks
 

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ascii(5)						Standards, Environments, and Macros						  ascii(5)

NAME
ascii - map of ASCII character set SYNOPSIS
cat /usr/pub/ascii DESCRIPTION
/usr/pub/ascii is a map of the ASCII character set, to be printed as needed. It contains octal and hexadecimal values for each character. While not included in that file, a chart of decimal values is also shown here. Octal - Character 000 NUL 001 SOH 002 STX 003 ETX 004 EOT 005 ENQ 006 ACK 007 BEL 010 BS 011 HT 012 NL 013 VT 014 NP 015 CR 016 SO 017 SI 020 DLE 021 DC1 022 DC2 023 DC3 024 DC4 025 NAK 026 SYN 027 ETB 030 CAN 031 EM 032 SUB 033 ESC 034 FS 035 GS 036 RS 037 US 040 SP 041 ! 042 " 043 # 044 $ 045 % 046 & 047 ' 050 ( 051 ) 052 * 053 + 054 , 055 - 056 . 057 / 060 0 061 1 062 2 063 3 064 4 065 5 066 6 067 7 070 8 071 9 072 : 073 ; 074 < 075 = 076 > 077 ? 100 @ 101 A 102 B 103 C 104 D 105 E 106 F 107 G 110 H 111 I 112 J 113 K 114 L 115 M 116 N 117 O 120 P 121 Q 122 R 123 S 124 T 125 U 126 V 127 W 130 X 131 Y 132 Z 133 [ 134 135 ] 136 ^ 137 _ 140 ` 141 a 142 b 143 c 144 d 145 e 146 f 147 g 150 h 151 i 152 j 153 k 154 l 155 m 156 n 157 o 160 p 161 q 162 r 163 s 164 t 165 u 166 v 167 w 170 x 171 y 172 z 173 { 174 | 175 } 176 ~ 177 DEL Hexadecimal - Character 00 NUL 01 SOH 02 STX 03 ETX 04 EOT 05 ENQ 06 ACK 07 BEL 08 BS 09 HT 0A NL 0B VT 0C NP 0D CR 0E SO 0F SI 10 DLE 11 DC1 12 DC2 13 DC3 14 DC4 15 NAK 16 SYN 17 ETB 18 CAN 19 EM 1A SUB 1B ESC 1C FS 1D GS 1E RS 1F US 20 SP 21 ! 22 " 23 # 24 $ 25 % 26 & 27 ' 28 ( 29 ) 2A * 2B + 2C , 2D - 2E . 2F / 30 0 31 1 32 2 33 3 34 4 35 5 36 6 37 7 38 8 39 9 3A : 3B ; 3C < 3D = 3E > 3F ? 40 @ 41 A 42 B 43 C 44 D 45 E 46 F 47 G 48 H 49 I 4A J 4B K 4C L 4D M 4E N 4F O 50 P 51 Q 52 R 53 S 54 T 55 U 56 V 57 W 58 X 59 Y 5A Z 5B [ 5C 5D ] 5E ^ 5F _ 60 ` 61 a 62 b 63 c 64 d 65 e 66 f 67 g 68 h 69 i 6A j 6B k 6C l 6D m 6E n 6F o 70 p 71 q 72 r 73 s 74 t 75 u 76 v 77 w 78 x 79 y 7A z 7B { 7C | 7D } 7E ~ 7F DEL Decimal - Character 0 NUL 1 SOH 2 STX 3 ETX 4 EOT 5 ENQ 6 ACK 7 BEL 8 BS 9 HT 10 NL 11 VT 12 NP 13 CR 14 SO 15 SI 16 DLE 17 DC1 18 DC2 19 DC3 20 DC4 21 NAK 22 SYN 23 ETB 24 CAN 25 EM 26 SUB 27 ESC 28 FS 29 GS 30 RS 31 US 32 SP 33 ! 34 " 35 # 36 $ 37 % 38 & 39 ' 40 ( 41 ) 42 * 43 + 44 , 45 - 46 . 47 / 48 0 49 1 50 2 51 3 52 4 53 5 54 6 55 7 56 8 57 9 58 : 59 ; 60 < 61 = 62 > 63 ? 64 @ 65 A 66 B 67 C 68 D 69 E 70 F 71 G 72 H 73 I 74 J 75 K 76 L 77 M 78 N 79 O 80 P 81 Q 82 R 83 S 84 T 85 U 86 V 87 W 88 X 89 Y 90 Z 91 [ 92 93 ] 94 ^ 95 _ 96 ` 97 a 98 b 99 c 100 d 101 e 102 f 103 g 104 h 105 i 106 j 107 k 108 l 109 m 110 n 111 o 112 p 113 q 114 r 115 s 116 t 117 u 118 v 119 w 120 x 121 y 122 z 123 { 124 | 125 } 126 ~ 127 DEL FILES
/usr/pub/ascii On-line chart of octal and hexadecimal values for the ASCII character set. SunOS 5.10 19 Apr 2002 ascii(5)
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