UNIX for Dummies Questions & Answers

Hi,

I have below code for disk creation

Code:

disk_list=$(ls /dev/sd[b-z])
for disk in $disk_list
do
pvcreate $i
done

So what my understanding is first it is checking the disk under /dev sdb,sdc,sdd,...sdz whether 25 disk are existing

if not then its creating the 25 physical volume.

I tried the below code from my local directory since can't take pvcreate risk

Code:

#!/bin/ksh
disk_list=$(ls /etc/mylocal/ab[a-c])
for i in $disk_list
do
touch  $i
done

I got below error

Code:

ls: cannot access /etc/mylocal/ab[a-c]: No such file or directory

I have not created any file like aba,abb...under my local so if the file not present then it should create all the files right why I am getting an error.

Please correct me if am I wrong

Hi,

We will need to see all the script I think, to me it should read more like;

Code:

for disk in `ls /dev/sd[b-z]`
do
pvcreate ${disk}
done

But you might want to put some error checking in place, I think - reading your additional post that you need a more fundamental understanding of things. The second script is failing because the files donot exist.

Regards

Dave

so you mean the first code pvcreation, will not go to for loop until /dev/sd[b-z] exist

Hi,

The script you show seems very strange to me, as if "/dev/sd[b-z]" exist then the physical volumes would normally be there. So the "pvcreate" command seems strange in this context.

It might be more apt if you were to explain in detail what it is that you want to do!

Regards

Dave

Hi stew

Code:

# Generate a list of device names that exist on your machine.
disk_list=$(ls /dev/sd[b-z])
for disk in $disk_list
do
# Avoid pvcreate risk!!
echo pvcreat $disk
done

This will generate a list of device names based on devices present on your machine, and then create the physical volumes if you remove 'echo '. Be sure of what you are doing! You can always remove volumes with pvremove if you mess up but your data on those drives will be gone!
No. If they DO exist the volumes will be created. pvcreate will fail if the devices are not present.

Code:

#!/bin/ksh
disk_list=$(ls /etc/mylocal/ab[a-c])
...
...

This code is pointless! Why have two identical lists? /etc/mylocal is where the disk names would come from, not where they are going.

Not sure where you got this script, but you shouldn't use it! Be very picky about which drives/partitions you use for an LVM and make sure you don't have important data on them!