[SOLVED] have trouble wrapping mind around bash for loops

smeezekitty · 10-08-2009, 01:03 AM

ok i want to use bash for looks as i am learning bash
why doesnt this print out 0-8

Code:

#!bash
for {set j 0} {$j<9} incr j {
echo $j
}

ghostdog74 · 10-08-2009, 01:05 AM

please go to the link in my sig to learn about bash.

smeezekitty · 10-08-2009, 01:06 AM

already went there
but the code aboive should work

smeezekitty · 10-08-2009, 01:55 AM

i got it -- it plays alittle jingle

Code:

freq=(100 200 300 400 500 600 500 400 300 200 100)
len=(1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000)
for j in {0..11}
do
echo "${freq[j]}"
setterm -blength ${len[j]} -bfreq ${freq[j]}; ./beep.dat
sleep 1
done
setterm -blength 750 -bfreq 600;echo;

beep.c:

Code:

#include <stdio.h>
int main(){
printf("%c", 7);
return 0;
}

compile with gcc -Wall beep.c -o beep.dat

lutusp · 10-08-2009, 03:19 AM

Quote:

Originally Posted by smeezekitty

ok i want to use bash for looks as i am learning bash
why doesnt this print out 0-8

Code:

#!bash
for {set j 0} {$j<9} incr j {
echo $j
}

The answer is simple -- it isn't a bash for-loop -- not remotely. Have you considered the radical idea of reading about Bash in one of the 100,000+ Web articles on this topic, including mine?:

Bash Shell Programming in Linux

Here is a freebie example of a Bash for-loop:

Code:

for y in {1..12}
do
   for x in {1..12}
   do
      printf "%4d" $((x*y))
   done
   echo ""
done

Here is the output:

Code:

   1   2   3   4   5   6   7   8   9  10  11  12                                                                              
   2   4   6   8  10  12  14  16  18  20  22  24                                                                              
   3   6   9  12  15  18  21  24  27  30  33  36                                                                              
   4   8  12  16  20  24  28  32  36  40  44  48                                                                              
   5  10  15  20  25  30  35  40  45  50  55  60
   6  12  18  24  30  36  42  48  54  60  66  72
   7  14  21  28  35  42  49  56  63  70  77  84
   8  16  24  32  40  48  56  64  72  80  88  96
   9  18  27  36  45  54  63  72  81  90  99 108
  10  20  30  40  50  60  70  80  90 100 110 120
  11  22  33  44  55  66  77  88  99 110 121 132
  12  24  36  48  60  72  84  96 108 120 132 144