Detect if USB drive is connected

Fixit7 · 05-30-2015, 07:35 AM

I use a bash script to backup files to an external drive.

What line could I add to determine if sdb1 is connected, and if not, display a message ?

Didier Spaier · 05-30-2015, 07:59 AM

Code:

if [ "`lsblk -o name|grep sdb1`" = "" ]; then echo "no device /dev/sdb1"; fi

If you get no output that doesn't mean that /dev/sdb1 is mounted, but you can mount it if you don't get the message and it's not already mounted. You can check the output of "mount" or of "lsblk -o name,mountpoint|grep sdb1 to see if it's already mounted.

veerain · 05-30-2015, 08:21 AM

That usb drive would have a filesystem and it may have a unique id. So use 'blkid' command to check presence of that uuid and do backup.

Fixit7 · 05-30-2015, 09:30 AM

# is.sh
/root/Scripts/is.sh: line 6: lsblk: command not found
no device /dev/sdb1

I found an example and tweaked it. Seems to work.

[ -e /mnt/sda1/Linux_Files/TOSHIBA_SDB1 ] && echo "Toshiba drive is connected" || echo "Toshiba Drive is NOT connected !!"

I have no idea what the -e is.

michaelk · 05-30-2015, 09:37 AM

I don't think puppy has lsblk or blkid.

http://www.tldp.org/LDP/Bash-Beginne...ect_07_01.html

Didier Spaier · 05-30-2015, 10:34 AM

Quote:

Originally Posted by Fixit7

I have no idea what the -e is.

In addition to the pointer michaelk gave you, try this:

Code:

man bash

But as this man page is huge and as bash is an implementation of the Shell Command Language you could begin with reading the relevant part of the POSIX specification that is easier to understand for beginners in my opinion. Just bear in mind that bash has also a lot of specific features.

PS your test checks that the USB drive is connected and mounted. I assume that's what you actually wanted.

jlinkels · 05-30-2015, 12:27 PM

I use it in my backup script as well. See the code snippet here: http://www.linuxquestions.org/questi...9/#post5363825

jlinkels

Fixit7 · 05-30-2015, 12:57 PM

Quote:

Originally Posted by Didier Spaier

In addition to the pointer michaelk gave you, try this:

Code:

man bash

PS your test checks that the USB drive is connected and mounted. I assume that's what you actually wanted.

My system is setup to mount all drives, but sometimes I do not have an external drive connected.

So I wanted to be notified when files are not being copied to that drive.

rknichols · 05-30-2015, 01:11 PM

If this is in a script, you could run the stat command on the mountpoint and verify that the "Device" field is different from that of the root filesystem.

For my own systems, my backup drives have only a subdirectory at their top level, and all backups are directed to that subdirectory, e.g., "/mnt/backups/bkups". If the drive is not mounted, that "bkups" directory won't exist, and the backup fails.

schneidz · 05-30-2015, 01:29 PM

Quote:

Originally Posted by Fixit7

...
I have no idea what the -e is.

http://linux.die.net/man/1/test

Fixit7 · 05-30-2015, 02:19 PM

Interesting, but my statement does not have test, just the -e ?

schneidz · 05-30-2015, 02:41 PM

[ is a synonym for test.

Keith Hedger · 05-30-2015, 06:07 PM

try the findmnt command, it is part of util-linux so should be available in most systems, also lsblk is part of the same package and does a similar thing to blkid also findfs

http://linux.die.net/man/8/findmnt

michaelk · 05-30-2015, 07:17 PM

I stand corrected...

http://puppylinux.org/wikka/util-linux