topic Re: nested if else statement in Operating System - HP-UX

nested if else statement

diwakar_4 — Mon, 17 Nov 2008 11:54:28 GMT

Hi all,

I want to execute if else in such a way:

Num=10
Char='Y'

if [ $Num = [0 OR 1 OR 2] ]; then
echo " Num is > 0 but < 3 "
else
if [ $Num = 3 OR 4] and $Char='Y' ];then
echo " num < 5 and char is : 'Y'
else
echo " num > 5 and char is : 'N'
fi;
fi;

Can some one please help me to right correctly these conditions.

Thanks

Re: nested if else statement

Ninad_1 — Mon, 17 Nov 2008 12:21:51 GMT

Hi,

The following will do,

Num=3
Char='Y'

if [ $Num -ge 0 -a $Num -lt 3 ] ; then
echo " Num is > 0 but < 3 "
elif [ $Num -eq 3 -o $Num -eq 4 ] ; then
if [[ $Char = 'Y' ]] ; then
echo " num < 5 and char is : 'Y'"
fi
elif [[ $Char = 'N' ]] ; then
echo " num > 5 and char is : 'N'"
else
echo " num > 5 and char is : 'Y' "
fi

Regards,
Ninad

Re: nested if else statement

Fredrik.eriksson — Mon, 17 Nov 2008 12:22:28 GMT

I think this would be easier solved by using Case statement instead of if's. But I'm guessing you have a plan for this so here we go :).

if [ $Num -ge 0 -a $Num -lt 3 ]; then
echo "Num is > 0 but < 3"
else
if [ $Num -ge 3 -a $Num -le 4 ]; then
if [ "$Char" == "Y" ]; then
echo " num < 5 and char is : 'Y'"
else
echo " num < 5 and char is : 'N'"
fi
elif [ $Num -ge 5 ]; then
if [ "$Char" == "Y" ]; then
echo " num > 5 and char is : 'Y'"
else
echo " num > 5 and char is : 'N'"
fi
fi
fi

I made som modifications to yours since it didn't account for all the possible versions. And I added a elif :)

Best regards
Fredrik Eriksson

Re: nested if else statement

diwakar_4 — Mon, 17 Nov 2008 12:45:35 GMT

Hi Ninad/Fredrik,

Thanks,

if [ $Num = 3 OR 4] and $Char='Y' ];then

I want above condition in one line rathar than spiliting in many lines.

Can you suggets..

Re: nested if else statement

Ninad_1 — Mon, 17 Nov 2008 12:52:24 GMT

Hi,

I do not see any benefit in putting everything in one line, except for code being a bit long.
Infact u should have the 2 conditions separate so as to also check for Char = N even if Num=3 or 4.

Regards,
Ninad

Re: nested if else statement

Dennis Handly — Mon, 17 Nov 2008 13:53:52 GMT

>I want condition in one line rather than splitting in many lines.
if [ $Num = 3 OR 4] and $Char='Y' ];then

if [ $ $Num -eq 3 -o $Num -eq 4 $ -a "$Char" = "Y" ]; then

Re: nested if else statement

V. Nyga — Mon, 17 Nov 2008 14:13:18 GMT

Hi,

why don't you also post your errors you've got?
In sh-shell or ksh-shell OR is ||, AND is &&:

if [[ $Num = 0 || $Num = 1 ]]; then
if [[ $Num = 10 && $Char = 'Y' ]]; then

Are we doing your homework?

Volkmar

Re: nested if else statement

Nitin Kumar Gupta — Tue, 18 Nov 2008 04:38:55 GMT

Hi Diwakar,

The shell script will be,

Num=10
Char='Y'

if [ $Num -eq 0 -o $Num -eq 1 -o $Num -eq 2 ]; then
echo " Num is > 0 but < 3 "
else
if [ $Num -eq 3 -o $Num -eq 4 ]&[ "$Char" = "Y" ];then
echo " num < 5 and char is : 'Y'"
else
echo " num > 5 and char is : 'N'"
fi
fi

--------------------------------------------
# OR
Num=10
Char='Y'

if [ $Num -eq 0 -o $Num -eq 1 -o $Num -eq 2 ]; then
echo " Num is > 0 but < 3 "
elif [ $Num -eq 3 -o $Num -eq 4 ]&[ "$Char" = "Y" ];then
echo " num < 5 and char is : 'Y'"
else
echo " num > 5 and char is : 'N'"
fi

OK Rules of the test for shell script:
Comparison operator
-------------------
- Numeric: -eq -ne -lt -le -gt -ge
- String: = !=

Logical operator
----------------
Numeric: ! Not
-a And
-o Or
String: ! Not
&& And
|| Or

OK,
- If you want to make two numeric comparision with and
if [ Cond1 -a Cond2 ];then # Here Cond like $a -lt 5

- If you want to make and with or
if [ Cond1 -a Cond2 -o Cond3 ];then

- But you want to change the order of testing
if [ Cond1 -s $ Cond2 -a Cond3 $ ];then
#Here spaces are important

- You want to compare two strings with and or or

if [ Cond1 ]&&[ Cond2 ]||[Cond3 ];then

Similarly you want to compare integer comparision with string with and

if [ intCond ]&&[ stringCond ];then

I hope now you will be able to do all possible comarisions.

Rgds
-NKG-

Re: nested if else statement

Nitin Kumar Gupta — Tue, 18 Nov 2008 04:42:02 GMT

Also,

for if, else, nested if else
1)
if ...
then
....
fi

2)
if ....
then
....
else
....
fi

3)
if ....
then
....
else
if ....
then
....
fi
fi

can be

if ....
then
....
elif ....
then
....
fi

I think you will be able to make all possible condition type.

Rgds
-NKG-

Re: nested if else statement

Dennis Handly — Tue, 18 Nov 2008 05:12:39 GMT

>Nitin: elif [ $Num -eq 3 -o $Num -eq 4 ]&[ "$Char" = "Y" ];then

That should be "&&":
elif [ $Num -eq 3 -o $Num -eq 4 ] && [ "$Char" = "Y" ]; then
Or using arithmetic expressions:
elif (( Num == 3 && Num == 4 )) && [ "$Char" = "Y" ]; then

>You want to compare two strings with and or or
if [ Cond1 ]&&[ Cond2 ]||[Cond3 ]; then

There is no need to use multiple test operators, you can use -a or -o

>if [ Cond1 -s $ Cond2 -a Cond3 $ ];then

I assume that -s should be -o.

Re: nested if else statement

Nitin Kumar Gupta — Tue, 18 Nov 2008 06:06:45 GMT

Hello Dennis,

Thanks to correct my typographical errors. And also thanks to tell me more about string comparisions.

-NKG-

Re: nested if else statement

Nitin Kumar Gupta — Tue, 18 Nov 2008 06:11:54 GMT

And Diwakar,

Your solution would be,

Num=10
Char='Y'

if [ $Num -eq 0 -o $Num -eq 1 -o $Num -eq 2 ]; then
echo "Num is > 0 but < 3"
elif [ $Num -eq 3 -o $Num -eq 4 ]&&[ "$Char" = "Y" ];then
echo "num < 5 and char is : 'Y'"
else
echo "num > 5 and char is : 'N'"
fi

-NKG-

Re: nested if else statement

diwakar_4 — Tue, 18 Nov 2008 08:15:26 GMT

Hi Dennis/Nitin,

Many thanks,

I got solution first from Deninis reply.

Also thanks Nitin for expaling very nicely.

Thanks

Re: nested if else statement

Fredrik.eriksson — Tue, 18 Nov 2008 08:20:35 GMT

Nitin,
I would not use the -eq num method.
If he needs to do this with a greater amount of numbers then 3 it'd be a pain and a long long line.

It's better to use greater and lesser then comparision.

if [ $Num -ge 0 -a $Num -le 2 ]; then
fi

Also the string comparision operator is not =, it's ==. Also a note for diwakar, don't forget the encapsulation with "".

if [ "$Char" == "Y" ]; then
fi

Best regards
Fredrik Eriksson

Re: nested if else statement

Dennis Handly — Tue, 18 Nov 2008 11:04:19 GMT

>Fredrik: Also the string comparison operator is not =, it's ==.

This is not the case in a real shell. == is only valid for arithmetic expressions (( )).
(Unless this is new for ksh 93?)