Shell Programming and Scripting

Hi i have to cut columns 2 to 6 from a file and assign it to arrays ,
The following code works

Code:

for ctcol in 2 3 4 5 6;
do 
set -A a$ctcol $(cut -d, -f $ctcol test_file)
done

how ever this does not work

Code:

for ctcol in {2..6};
do 
set -A a$ctcol $(cut -d, -f $ctcol test_file)
done

Kindly let me know what is wrong with it

From what I know, range expansion {2..6} is a part of modern bash shell's parameter expansion feature and not a feature of ksh.

An alternative that will work for sure (even in old bourne shells):

Code:

i=2
while [ $i -le 6 ]
do
    <statements>
    i=`expr $i + 1`
done

Another alternative that will work on ksh:

Code:

for i in $(seq 2 6)
do
    <statements>
done

In any version of ksh newer than November 16, 1988, you can also use:

Code:

for ((i=2; i<=6; i++))
do  <statements>
done

Although not available in the original 1993 version of ksh, the:

Code:

for ctcol in {2..6}
do  ...
done

does work in recent versions of ksh93 including version s+ (sh (AT&T Research) 1993-12-28 s+) as provided with Apple's OS X 10.7.5.

And, in any standards conforming shell (including ksh versions newer than 1988 and bash) you could also use:

Code:

i=2
while [ $i -le 6 ]
do  <statements>
    ((i++))
done

The seq utility suggested above by balajesuri will work on most Linux systems, but is not available on some UNIX systems.

Thanks for the detailed explanation along with the release dates of ksh. Very informative

Thanks that was really helpful