for loop throwing an error

Shell Programming and Scripting
1

Hi Guys,

I am trying a simple for loop which is throwing an error.
Below is my code:

#/bin/sh

set -A array "are" "you" "there";

for ( i = 0 ; i < ${#array[@]} ; i++ )
do
echo ${array[$i]}
done

I am getting this error

tci001wasd02 $ sh -vx array_for.sh
#/bin/sh

set -A array "are" "you" "there";
+ set -A array are you there

for ( array_for.sh[5]: 0403-057 Syntax error at line 5 : `(' is not expected.

I even tried with "((" in the for loop.

Thanks for your help in advance.

Regards,
Magesh

2

Something like this should work:

 
#/bin/sh
array=( are you there )
i=0
j=${#array
[*]}
while [ $i -ne $j ]
do
echo ${array[$i]}
i=`expr $i + 1`
done
3

ya vi-curious,,

I have wrote a script with While loop.. its working fine..but i want to try for loop syntax in unix instead of while..

isn't "for loop" not possible in unix?

My while script:

#/bin/sh

set -A array "are" "you" "there";
a=0;
while [ "$a" -le "2" ]
do
for i in ${array[$a]}
do
echo $i;
a=$((a+1));
done
done
4

I did the while loop so that it would not be dependent on the array size but I see from your while loop that you were not concerned about that. So, for loop looks like this:

#/bin/sh

array=( are you there )

#for i in 0 1 2
for i in ${!array[@]}
do
echo ${array[$i]}
done
5

The standard Unix shell does not have arrays, so you should use a shebang that indicates which shell you are using.

That syntax is, I believe, ksh93, so your script should begin with:

#!/usr/bin/ksh93

(Or wherever your ksh93 is hiding.)

That is non-standard syntax; it isn't even correct for bash and ksh93 which use something similar:

for (( i = 0 ; i < ${#array[@]} ; i++ ))

I think that's right; I avoid non-standard syntax when it offers nothing more than the standard.

The following is not standard because of the array, but the for syntax is standard:

for i in "${!array[@]}"
6

@cfajohnson,
Thanks for pointing out the errors, i have changed the sh to ksh93.

But even now i am not able to run the for command.

tci001wasd02 $ cat array_for.sh
#/bin/ksh93

set -A array "are" "you" "there";

for (( i = 0 ; i < ${#array[@]} ; i++ ))
do
echo ${array[$i]}
done
tci001wasd02 $ sh -vx array_for.sh
#/bin/ksh93

set -A array "are" "you" "there";
+ set -A array are you there

for ((array_for.sh[5]: 0403-057 Syntax error at line 5 : `(' is not expected.

the command u mentioned above

for i in "${!array[@]}"

will give me all the elements in the array. But i want only certain elements from the array, which i wanted to do it using a for loop...

Please help me in doing the above.

Thanks & Regards,
Magesh

7

I would use the more portable (though arrays are not standard) form of assigning an array:

array=( are you there )   ## doesn't work in ksh88, AFAIK

Then use the standard syntax.

(That works for me in ksh93; perhaps you are using a different version of ksh93. All the more reason to use the standard syntax; it will work in all versions and other shells.)

Both forms give you all the elements in the array. You have to select the ones you want inside the loop.

Always use the standard syntax when possible without losing efficiency. Non-standard features may (and often do) change from one verion of a shell to the next.