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I run a little script that prints the available space for file system:

Code:

#!/usr/bin/perl5
sub CheckDiskSpace
{
    use Filesys::DiskFree;
    my $handle = new Filesys::DiskFree;
    $handle->df();

$loc1 = '/dev';
$loc2 = '/var/run';
$loc3 = '/boot';
print "... $loc1, $loc2, $loc3, '/' \n";

    foreach my $file ($loc1,$loc2,$loc3,'/' )
    {
        my $bytesavailable=$handle->avail($file);
        print "at $file, available bits = $bytesavailable \n";
    }
}

CheckDiskSpace();
[download]

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The result is:

... /dev,/var/run,/boot,'/'

at /dev, available bits = 1028820992

at /var/run, available bits = 1028730880

at /boot, available bits =

at /, available bits =

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I then type command "df -a" and get:

Code:

Filesystem           1K-blocks      Used Available Use% Mounted on
proc                         0         0         0   -  /proc
/sys                         0         0         0   -  /sys
varrun                 1004736       116   1004620   1% /var/run
varlock                1004736         0   1004736   0% /var/lock
udev                   1004736        28   1004708   1% /dev
devshm                 1004736        12   1004724   1% /dev/shm
devpts                       0         0         0   -  /dev/pts
tmpfs                  1004736        12   1004724   1% /dev/shm
securityfs                   0         0         0   -  /sys/kernel/se
+curity
gvfs-fuse-daemon     620395268  10647256 609748012   2% /root/.gvfs
/dev/sda1               497829    139305    332822  30% /media/_boot
[download]

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I then run "gparted" and tt shows /dev/sda3 is mounted to '/' and '/dev/.static/dev'. It's a graphic tool and I do not know how to post pictures here.

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The thing I do not understand is: Why cannot perl script tell the available size of "/"? Why doesnot df command show "/" as a mount point while gparted correctly shows that? I tried to mount /dev/sda3 to '/' but it says it already exists. My system is ubuntu server. Can someone help me? Thanks.