CODEWITHSUNDEEP
bashmacosfilesystemsdiskstat
az5112
az5112

Reputation: 642

How to obtain the name of the disk given the disk ID?

The stat system call (man 2 stat) returns the ID of the device containing the file.

In a script, this ID can be obtained with, say

perl -e 'print((stat "/tmp/blah.txt")[0])'

Given the ID, how do I obtain the name of the disk, such as /dev/sda2 or /dev/disk1s1?

I want to do it in a script (bash, perl, etc.) preferably in a portable way so that it works reliably both on MacOS and Linux.

Upvotes: 2

Views: 1007

Answers (2)

oguz ismail
oguz ismail

Reputation: 50805

I think you're trying to re-invent the wheel.
Given a file name, the filesystem name it belongs to can be found in last row's first column in df's output. E.g:

df -P /tmp | awk 'END { print $1 }'

Upvotes: 1

dash-o
dash-o

Reputation: 14491

You can use 'df' to enumerate the file system, and create a map between device IDs and disk. Recall the each df line will list the mount point (/dev/sda1, ...) in the first column, and the mount point on the 5th column).

The following script uses bash associative array for the map, and stat -c '%d' to extract the 'dev' value of a given path.

# Create map dev2fs
function file2dev {
   stat -c '%d' "$1"
# If needed, use Perl equivalent
#    perl -e 'print ((stat($ARGV[0]))[0])' "$1"
}

declare -A dev2fs
while read fs size used available use mount ; do
    id=$(file2dev $mount);
    [ "$id" ] &&  dev2fs[$id]=$fs
done <<< "$(df)"

# Map a file to device
dev=$(file2dev /path/to/file );
echo "Device=${dev2fs[$dev]}"

Also, possible to iterate over mounted file system using 'mount -l'. I'm not sure which one exists on MacOS.

Upvotes: 1

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