Extracting USB device names from /dev/disks/

kushalkoolwal · 01-30-2009, 02:55 PM

Hello,

I am trying to write a shell script which will list all the USB devices (storage media) present on the system. So far I can get name of the USB devices (/dev/sd*) with the following command:

Code:

find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]'

which returns the following output:

Code:

/dev/sdd
/dev/sdc
/dev/sdb

However I would also like to prefix the above output with their model name/number. Here is what my /dev/disk/by-id looks like:

Code:

debian:~# ls -l /dev/disk/by-id/ | grep usb | grep -v part
lrwxrwxrwx 1 root root  9 2009-01-30 12:31 usb-JMicron_USB_to_ATA.ATAPI_Bridge_152D203380B6-0:0 -> ../../sdb

lrwxrwxrwx 1 root root 10 2009-01-30 12:32 usb-LITE-ON_DVDRW_SHM-165P6S_DEF10CB84245-0:0 -> ../../scd1

lrwxrwxrwx 1 root root  9 2009-01-30 12:31 usb-SanDisk_uSSD_5000_20052444330A224035EA-0:0 -> ../../sdc

lrwxrwxrwx 1 root root  9 2009-01-30 12:31 usb-WDC_WD80_0BB-00CAA1_0B00012105E7C8E5-0:0 -> ../../sdd
debian:~#

Now ideally I would like to extract the model name (and number if possible) for each of the usb devices (/dev/sd*) and display it like this:

Code:

/dev/sdd usb-WDC_WD80
/dev/sdc usb-SanDisk_uSSD
/dev/sdb usb-JMicron_USB_to_ATA.ATAPI_Bridge

colucix · 01-30-2009, 04:51 PM

Code:

#!/bin/bash
devlist=$(find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]')
for device in $(echo $devlist)
do
  long_name=$(grep ${device##*/}$ testfile | awk '{print $8}')
  echo "${device} ${long_name%%_[0-9]*}"
done

kushalkoolwal · 01-30-2009, 05:15 PM

Quote:

Originally Posted by colucix

Code:

#!/bin/bash
devlist=$(find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]')
for device in $(echo $devlist)
do
  long_name=$(grep ${device##*/}$ testfile | awk '{print $8}')
  echo "${device} ${long_name%%_[0-9]*}"
done

Hmm...I tried running the script but I got error messages:

Code:

debian:~# ./get_usb.sh 
grep: testfile: No such file or directory
/dev/sdd 
grep: testfile: No such file or directory
/dev/sdc 
grep: testfile: No such file or directory
/dev/sdb 
debian:~#

What is testfile? Looks like it suddenly came from nowhere.

Thanks

colucix · 01-30-2009, 05:23 PM

Uh, sorry. Just tested on my system copying the output from your command. Forgive me. Here is the correct version:

Code:

#!/bin/bash
devlist=$(find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]')
for device in $(echo $devlist)
do
  long_name=$(ls -l /dev/disk/by-id/ | grep usb | grep -v part | grep ${device##*/}$ | awk '{print $8}')
  echo "${device} ${long_name%%_[0-9]*}"
done

kushalkoolwal · 01-30-2009, 05:31 PM

Quote:

Originally Posted by colucix

Uh, sorry. Just tested on my system copying the output from your command. Forgive me. Here is the correct version:

Code:

#!/bin/bash
devlist=$(find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]')
for device in $(echo $devlist)
do
  long_name=$(ls -l /dev/disk/by-id/ | grep usb | grep -v part | grep ${device##*/}$ | awk '{print $8}')
  echo "${device} ${long_name%%_[0-9]*}"
done

Wohhhhhaaa dude awesome. Worked like a charm. You are amazing.

Taking your "thanked" count to 83....

colucix · 01-30-2009, 05:34 PM

Quote:

Originally Posted by kushalkoolwal

Taking your "thanked" count to 83....

He he... thank you!

A little gift for you: your first thanked post!

kushalkoolwal · 01-30-2009, 05:42 PM

Hi colucix,

Instead of blindly using your code, I was trying to understand how it works and I think I pretty much got it except the following two marked in red color:

Code:

#!/bin/bash
devlist=$(find /dev/disk/by-path/ -type l -iname \*usb\*scsi\* -print0 | xargs -0 -iD readlink -f D  | grep -v '[0-9]')
for device in $(echo $devlist)
do
  long_name=$(ls -l /dev/disk/by-id/ | grep usb | grep -v part | grep ${device##*/}$ | awk '{print $8}')
  echo "${device} ${long_name%%_[0-9]*}"
done

Thanks

colucix · 01-30-2009, 05:49 PM

They are examples of parameter substitution in bash. The first one means "strip the longest part of the pattern that matches the front end of the variable":

Code:

${device##*/}

suppose the $device variable is /dev/sdd. The pattern is */. Hence everything before the last slash (included) is removed from the string (leaving just the sdd part). Regarding the $ sign at the end of the grep pattern, it means "at the end of the line".

The second one means "strip the longest part of the pattern that matches the back end of the variable":

Code:

${long_name%%_[0-9]*}

this strip the last part of the string $long_name from the first underscore that comes immediately before a digit (not a character), that is the part in red:

Code:

usb-SanDisk_uSSD_5000_20052444330A224035EA-0:0

Hope it is clear now.

Reference: http://www.tldp.org/LDP/abs/html/par...stitution.html

kushalkoolwal · 01-30-2009, 06:14 PM

Yes it is. Thank you once again.