[CentOS] df to get total disk usage on all filesystems?

Stephen Harris lists at spuddy.org
Thu Aug 14 23:00:57 UTC 2008


On Thu, Aug 14, 2008 at 03:23:24PM -0700, Nifty Cluster Mitch wrote:
> On Thu, Aug 14, 2008 at 02:45:43PM -0700, MHR wrote:
> > On Thu, Aug 14, 2008 at 2:36 PM, Nifty Cluster Mitch

> > > $ cat /tmp/checkspace
> > > #!/bin/bash
> > > df -Pkl > /tmp/checkingdiskspce
> > > echo -e "\nInput is:"
> > > cat /tmp/checkingdiskspce
> > > echo -e "\nAdding up the bits"
> > > cat /tmp/checkingdiskspce | awk '/^\/dev\// { used += $3/1024 } END { printf("%d Mb Used\n", used)} '
> > 
> > This is simpler (and does not involve as many execs & forks) as:
> > 
> > awk '/^\/dev\// { used += $3/1024 } END { printf("%d Mb Used\n",
> > used)} ' /tmp/checkingdiskspce
> 
> True, yet if the goal is "df | awk" with no tmp file at all the final
> edit and cleanup is cleaner.  If the goal is to present the result of

Boggle-riffic!  if you want to see the input as well, then do it in the
awk side.  So we have a "df" and an "awk"; one pass through the
output... everything is optimal!

df -Pkl | awk 'BEGIN { print "\nInput is:" }
               { print $0 }
               /^\/dev\// {used += $3/1024 }
               END { printf("\nAdding up the bits:\n%d MB Used\n",used)}'

Input is:
Filesystem         1024-blocks      Used Available Capacity Mounted on
/dev/sda6              4061540   3182144    669752      83% /
/dev/sda5            449567400  28064608 398297708       7% /datadisk
/dev/sda3                93327     11124     77384      13% /boot
tmpfs                  2041736         0   2041736       0% /dev/shm

Adding up the bits:
30525 MB Used


(of course I only made that multiple lines for readability; you could put
it all on one line if you really wanted to :-))

> I did notice in this discussion that no one looked at inode counts.
> A filesystem might be "full" for want of an inode....  I cannot

When you're adding up all used space over multiple disks you're not
concerned with a disk filling up.  You're just looking for total usage.
Off the top of my head I can only think of one (bad) reason to do it;
some sort of billing system.

The numbers don't even taken into account the %age of space reserved for
root :-)

> Other interesting system admin topics not addressed includes sparse files.  For some
> knowing about sparse files is important for backup tools.   Also  allocation block size

Only for broken backup tools that don't handle sparse files :-)  And, yes,
I had one of those in 1990... tar on a DEC Ultrix 3.1 system doesn't grok
sparse files.  Bleh!  Fortunately "dump" did it properly.

-- 

rgds
Stephen


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