how can i do some action when 'ctrl+d' is pressed

Shell Programming and Scripting
1

hi Gurus, please why is this happening:
when i run this:

#!/bin/bash
declare -a name
declare -a ph
declare -a eid
r=0;
c=1;
i=1;
n=;
echo "         name    phone    email_id"    
while :
do
 #if [ $i>$n ]; then
   #break;
 #else  
   echo -n "field $i:"; read name[$r$c] ph[$r$c] eid[$r$c];
   let "i++";
   let "c++";
 #fi
done
#echo "the values of fields are :"

#for((i=1;i<=n;i++))
#do
 # echo "field$i:${fld[$r$i]}    ${typ[$r$i]}    ${con[$r$i]}" 
#done

when i keep on entering the values, the while loop runs uptil c=7 for c=8 it gives error like:

prayush@prayush-desktop ~/Desktop $ grun.bash ./ex2
         name    phone    email_id
field 1:abc    4327543 jhasdf@fdsj
field 2:sdf 23553    asf@sgfdfg
field 3:adsf    578543    asdfjdsaf
field 4:ahdfjhjk    4795636    gfhdhsdh
field 5:hretiuewndf    9805687954      fdsfjkfkj
field 6:asdfadsf
field 7:
field 8:
./ex2: line 15: 08: value too great for base (error token is "08")

when in Ist code ,if i make r=1, then it becomes an infinite loop. secondly when i uncomment if-else & for code in the script it skips the code with in 'else' and put null in the array variables .
still the problem of "value too great for base (error token is "08")" remains the same for r=0 & n>=8,for r=1 & n>=8 the 'while loop' breaks as per the condition.

heres the output:

 prayush@prayush-desktop ~/Desktop $  ./ex2
         name    phone    email_id
the values of fields are :
field1:        
field2:        
field3:        
field4:        
field5:        
field6:        
field7:        
./ex2: line 24: 08: value too great for base (error token is "08")

what i actually wanted to do was, to read the values of variable until ctrl+d or ctrl+c or may be with any combination with 'ctrl' or 'Alt' if u can suggest. And when this shortkey is pressed i want to perform some custom actions.

2

You use 01 02 03 04 .. 07 as array indices, which is unusual. I suspect these number get interpreted as octal numbers instead of decimal numbers, hence 08 would be to big for the base and it should be 10 (equals decimal 8).

3

thanks scruitizer!! that could be the case!!!!!!
But what about the problem of skipping the code when i uncomment 'if-else & for' code. the script is behaving differently!!

4

Hi tprayush,

You are doing a lexicographical comparison (">") instead of a numerical comparison ("-gt"). So instead of

if [ $i>$n ]; then

you should use

if [ $i -gt $n ]; then

or preferably:

if [[ $i -gt $n ]]; then

or use an arithmetic evaluation:

if (( i > n )); then
5

thanks Scrutinizer for your help..
but i don't get the meaning of 'lexicographical comparison`!!!

6

Alphabetical or "dictionary" order, typically it means using ASCII ordering.
so e.g. 100<2<23<39<4, whereas the numerical order is 2<4<23<39<100.