how to manipulate the loop by stdin

[huangwason]

I am going to write a loop, e.g
for (i=1; i<=10; i++)
do
echo "do test $i"
read
done

I would like to manipulate the loop manually. For instance, assume i=4 now, in the interval, when I press +, then perform next test 5, if I press -, then perform the previous test 3.
How to fulfill it? Thanks

 

[feherke]

Hi

Then why the [tt]for[/tt] loop ? And how you intend to leave the loop ?

Feherke.

http://rootshell.be/~feherke/

 

[huangwason]

Basically, any loop is ok as long as I could manipulate it. Here I only take an example.

 

[feherke]

Hi

Then I would start with something like this :

i=0
[b]while[/b] :; [b]do[/b]
  [b]echo[/b] [i]"do test $i ? ( + next / - prev / x exit )"[/i]
  [b]read[/b] c
  [b]case[/b] [i]"$c"[/i] [b]in[/b]
    [i]'+'[/i]) (( i++ )) ;;
    [i]'-'[/i]) (( i-- )) ;;
    [i]'x'[/i]) break ;;
  [b]esac[/b]
[b]done[/b]

What shell are you using ?

Feherke.

http://rootshell.be/~feherke/

 

[huangwason]

Thanks, I use bash

 

[feherke]

Hi

Good. [tt]bash[/tt]'s [tt]read[/tt] support the -n option :

If -n is supplied with a non-zero NCHARS argument, read returns after NCHARS characters have been read.

This way you can achieve a [tt]getch[/tt]/[tt]readkey[/tt]/[tt]inkey[/tt] behavior :

i=0
[b]while[/b] :; [b]do[/b]
  [b]read[/b] -p [i]"do test $i ? ( + next / - prev / x exit )"[/i] -n 1 c
  [[ [i]"$c"[/i] ]] && [b]echo[/b]
  [b]case[/b] [i]"$c"[/i] [b]in[/b]
    [i]'+'[/i]) (( i++ )) ;;
    [i]'-'[/i]) (( i-- )) ;;
    [i]'x'[/i]) [b]break[/b] ;;
  [b]esac[/b]
[b]done[/b]

Feherke.

http://rootshell.be/~feherke/