for loop - reverse reading

Shell Programming and Scripting
1

All,

Here is my for loop

export CFGLIST="LIST1 LIST2 LIST3"
 
for i in $CFGLIST
do
  echo print $i
done

The output will be

LIST1
LIST2
LIST3

But i want it display

LIST3
LIST2
LIST1

Can you please help me how to read in reverse order?

Thanks
Bala

2 
 
a="LIST1 LIST2 LIST3"
$ echo $a | nawk '{for(i=NF;i>=1;i--){print $i}}'
LIST3
LIST2
LIST1
3 
#!/bin/bash

CFGLIST=(LIST1 LIST2 LIST3)
i=${#CFGLIST
[*]}
((i-=1))
while [ $i -ge 0 ]
do
  echo ${CFGLIST[$i]}
  ((i-=1))
done

--ahamed

4

kamaraj, i'm finding difficulty without nawk - Thanks

Ahamed - if i have as below

CFGLIST=("LIST1 LIST2 LIST3") - It returns same value

Can you please help?

Thanks
Bala

5

use awk instead of nawk

---------- Post updated at 05:54 PM ---------- Previous update was at 05:49 PM ----------

 
$ echo $CFGLIST | perl -lane 'print join(" ",reverse @F)' 
LIST3 LIST2 LIST1
6

A simple Shell method:

export CFGLIST="LIST1 LIST2 LIST3"
set ${CFGLIST}
echo "$3"
echo "$2"
echo "$1"

./scriptname
LIST3
LIST2
LIST1
7 
export CFGLIST="LIST1 LIST2 LIST3"

revlist=
for i in $CFGLIST
do
  revlist="$i $revlist"
done

for i in $revlist
do
  echo "print $i"
done
8

A more complicated Shell method for any number of items:

export CFGLIST="LIST1 LIST2 LIST3"
set ${CFGLIST}
items=$#
counter=$items
while [ $counter -ne 0 ]
do
        eval output=\$${counter}
        echo "${output}"
        counter=$((${counter} - 1))
done

./scriptname
LIST3
LIST2
LIST1
9

Just for the fun of it since there are 18 ways to do most tasks (some better than others), how about using an array (ksh93 on solaris)?

#!/usr/dt/bin/dtksh

export CFGLIST="LIST1 LIST2 LIST3"

# Turn it into an array
set -A CFGLIST $CFGLIST

# Array is zero-based so start one less than the number of elements.
for (( i=$((${#CFGLIST
[*]}-1));i>=0;i-- ))
do
  print "Array element ${i}: ${CFGLIST[${i}]}"
done

exit 0

Output:

$ efs
Array element 2: LIST3
Array element 1: LIST2
Array element 0: LIST1
$