Question on Shell Script

manickaraja · 02-09-2010, 08:02 AM

Hi,
Below is the requirement. Please let me know if anyone can suggest a solution.

There is a host variable by name MOUNT1 which holds value /ora1

$ echo $MOUNT1
/ora1

Similarly there are 5 variables (MOUNT1 thorugh MOUNT5) with different mount point values. The number suffix after MOUNT (1 in above example) is coming dynamically from a varaible VAR

$ echo $VAR
1

The value of VAR will vary in a loop (first time it will be 1, second time it will be 2 etc.. after reaching 5 it will again start from 1)

Now how do I get the "/ora1" value inside the loop.

Something like echo $MOUNT$VAR. But its not simple. echo $MOUNT$VAR will not work (it will just return 1 instead of /ora1). Let me know if any of you can find the answer. Please let me know incase if you could not understand the puzzle.

angel115 · 02-09-2010, 08:21 AM

The following should do:

Code:

echo $( eval \$MOUNT$VAR )

colucix · 02-09-2010, 08:35 AM

I think it's better

Code:

eval echo \$MOUNT$VAR

otherwise the shell tries to execute the value of the variable as a command. Some details about indirect variable reference, here.

tuxdev · 02-09-2010, 09:44 AM

Use Arrays:
http://mywiki.wooledge.org/BashFAQ/005

crts · 02-09-2010, 10:07 AM

Quote:

Originally Posted by manickaraja

Hi,
Below is the requirement. Please let me know if anyone can suggest a solution.

There is a host variable by name MOUNT1 which holds value /ora1

$ echo $MOUNT1
/ora1

Similarly there are 5 variables (MOUNT1 thorugh MOUNT5) with different mount point values. The number suffix after MOUNT (1 in above example) is coming dynamically from a varaible VAR

$ echo $VAR
1

The value of VAR will vary in a loop (first time it will be 1, second time it will be 2 etc.. after reaching 5 it will again start from 1)

Now how do I get the "/ora1" value inside the loop.

Something like echo $MOUNT$VAR. But its not simple. echo $MOUNT$VAR will not work (it will just return 1 instead of /ora1). Let me know if any of you can find the answer. Please let me know incase if you could not understand the puzzle.

Hi,

I'm not sure if I understand the problem but I tried the following:

Code:

for VAR in $(seq 5); do
 echo $MOUNT$VAR
done

and this resulted in

Code:

/ora1
/ora2
/ora3
/ora4
/ora5

Is this the output you expected?
- If yes, are you using this loop in a script? Was MOUNT declared outside that script? Are you using pipes?
- If no, please post the code that you tried to execute

manickaraja · 02-12-2010, 06:56 AM

Thanks a lot for all your help and guidance. I was able to resolve the issue by using below command.

eval echo \$MOUNT$VAR

Thanks,
Manick.