9

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

1 Answer 1

6

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
    
4
  • 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
    Commented Feb 6, 2012 at 23:57
  • 2
    I replaced the ? with a *
    – LVLAaron
    Commented Feb 7, 2012 at 0:10
  • Yep, that was the right thing to do there. I hadn't thought about what happens if you have a lot of drives.
    – Mat
    Commented Feb 7, 2012 at 13:08
  • Technically you gave me exactly what I asked for, I only specified one X. :)
    – LVLAaron
    Commented Feb 7, 2012 at 15:00

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