Ruby module to get df -h output

ruby-talk
1

Hi
i can get mount information by using
`df -h`

but wondering, if is there is any ruby module which will go through the
LInux mount information

basically i want to see

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/cciss/c0d0p3 134G 12G 116G 9% /
tmpfs 16G 0 16G 0% /dev/shm
/dev/cciss/c0d0p1 194M 28M 157M 15% /boot
/dev/cciss/c0d1p1 270G 1.5G 254G 1% /var/www/html

if /dev/cciss/c0d1p1 is mounted or not

as i SAid i can do this by df -h command

but i m trying to see if i can do this by using ruby modules

Thanks

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2

You could easily write one in around 23 lines of code:

class MountPoints
  # Left as an exercise for the reader
end

mp = MountPoints.new

mp.is_mounted("/dev/disk2s2") => true
mp.is_mounted("/dev/disk3s2") => false

Well those values are correct for my system :slight_smile:

I doubt that there is a gem that does nothing but this given the
trivial nature of the problem.

There is however a simpler solution. The File class:

irb(main):001:0> File.exists?("/dev/disk2s2")
=> true
irb(main):002:0> File.exists?("/dev/disk3s2")
=> false

3

Peter Hickman wrote in post #1074238:

I doubt that there is a gem that does nothing but this given the
trivial nature of the problem.

http://sysutils.rubyforge.org/
->

There is however a simpler solution. The File class:

irb(main):001:0> File.exists?("/dev/disk2s2")
=> true

But that doesn't tell you if it is mounted or not.

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4

Depends on your need

Here is the out put from 'df -h' on my system'

Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s2 465Gi 385Gi 80Gi 83% /
devfs 191Ki 191Ki 0Bi 100% /dev
map -hosts 0Bi 0Bi 0Bi 100% /net
map auto_home 0Bi 0Bi 0Bi 100% /home
/dev/disk2s2 1.4Ti 489Gi 908Gi 36% /Volumes/Backup
/dev/disk1s6 466Gi 317Gi 148Gi 69% /Volumes/Spare

Now insert a new drive and do it again

Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s2 465Gi 385Gi 80Gi 83% /
devfs 195Ki 195Ki 0Bi 100% /dev
map -hosts 0Bi 0Bi 0Bi 100% /net
map auto_home 0Bi 0Bi 0Bi 100% /home
/dev/disk2s2 1.4Ti 489Gi 908Gi 36% /Volumes/Backup
/dev/disk1s6 466Gi 317Gi 148Gi 69% /Volumes/Spare
/dev/disk3s1 56Mi 37Mi 19Mi 66% /Volumes/Untitled

Note the new filesystem => /dev/disk3s1

ruby-1.8.7-p302 > File.exists?("/dev/disk3s1")
=> true
ruby-1.8.7-p302 >

Now I remove the disk and we go back to how it was

Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s2 465Gi 385Gi 80Gi 83% /
devfs 193Ki 193Ki 0Bi 100% /dev
map -hosts 0Bi 0Bi 0Bi 100% /net
map auto_home 0Bi 0Bi 0Bi 100% /home
/dev/disk2s2 1.4Ti 489Gi 908Gi 36% /Volumes/Backup
/dev/disk1s6 466Gi 317Gi 148Gi 69% /Volumes/Spare

See that /dev/disk3s1 is no longer there

ruby-1.8.7-p302 > File.exists?("/dev/disk3s1")
=> false
ruby-1.8.7-p302 >

So as far as my system is concerned /dev/disk3s1 only exists when it
is mounted. This may be sufficient for the task that the OP had. Now I
will concede that it might not work how you might expect for other
devices. File.exists?("/dev/disk0s1") which is not in the df -h list
does return true as it is part of /dev/disk0s2. But the the OP didn't
want to know if "/var/www/html" was mounted (or that the mount point
existed) just that "/dev/cciss/c0d1p1" was mounted, the example that
the OP gives would be true if "/dev/cciss/c0d1p1" was mounted to *any*
mount point not just "/var/www/html".

As I've said File.exists?() might be a sufficient solution for the OP.

5

Peter Hickman wrote in post #1074298:

So as far as my system is concerned /dev/disk3s1 only exists when it
is mounted.

While the drive is inserted, type "umount /dev/disk3s1" and you will be
in a position where the disk exists but is not mounted. Ejecting via a
GUI filemanager is probably the same.

But the the OP didn't
want to know if "/var/www/html" was mounted (or that the mount point
existed) just that "/dev/cciss/c0d1p1" was mounted, the example that
the OP gives would be true if "/dev/cciss/c0d1p1" was mounted to *any*
mount point not just "/var/www/html".

Correct - which you can't tell by looking at whether /dev/cciss/c0d1p1
exists.

But as you say, only the OP knows what solution they actually need.

Regards,

Brian.

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