"echo 1 > /sys/block/sdX/device/delete" on all disks except predetermined list

Question

I have a list of scsi disks that I need to remove. The list is considered random at best and changes from time to time. I want to remove everything except a predefined list that I have created. Let's assume for now that I only want to keep:

/dev/sda
/dev/sdb

The command I need to execute is:

"echo 1 > /sys/block/sdX/device/delete"

Where X is the device to be removed.

I'm not good at bash scripting so I don't really know where to start.

To recap so I don't get DV'd for not being clear.

I need to "echo 1 > /sys/block/sdX/device/delete" for every sdX device on the system except for a predetermined list.

EDIT: After the answer below, this is what I've decided to use. "LocalDisks.txt" should contain lines like "/dev/sda"

#!/bin/bash
exclude=$(cut -d/ -f3 LocalDisks.txt)
for sysfile in /sys/block/sd* ; do
dev=$(basename $sysfile)
del=$sysfile/device/delete
if [[ $exclude == *$dev* ]] ; then
    echo "Device $dev excluded"
elif [ ! -w $del ] ; then
    echo "$del does not exist or is not writable"
else
    echo 1 > $del
fi
done

Solution

Here's an approach that should work:

• Get the list of sdX devices to exclude

  exclude=$(cut -d/ -f3 exclude.txt)
  

• Iterate over the /sys/block/sdX directories:

  for sysfile in /sys/block/sd? ; do
  

• Extract the sdX name from that path, and build the delete file name

    dev=$(basename $sysfile)
    del=$sysfile/device/delete
  

• Check if that sdX is in the excluded list:

    if [[ $exclude == *$dev* ]] ; then
      echo "Device $dev excluded"
  

• Check if you have appropriate write permissions on the delete file

    elif [ ! -w $del ] ; then
      echo "$del does not exist or is not writable"
  

• Do the delete (not really)

    else
      echo "echo 1 > $del"
    fi
  

• You're done!

  done
  

Comments

[LVLAaron]

I do think that this will work out. However, I need to make one adjustment. I have so many disks that some are /dev/sdXX - if I add a question mark to the one you already have it only returns the /dev/sdXX and if there's only one question mark, it only returns the ones like /dev/sdX. Makes sense... How can it service both?

[LVLAaron]

I replaced the ? with a *

[Mat]

Yep, that was the right thing to do there. I hadn't thought about what happens if you have a lot of drives.

[LVLAaron]

Technically you gave me exactly what I asked for, I only specified one X. :)