I am a desktop support professional with experience working in a corporate call center environment. Recently, I started to admin RHEL based IBM Linux server. How do I determine how much disk space left in my Linux server? How do I find out how much disk space I have in Linux for each partition?

You need to use the df command. It shows the amount of disk space available on the currently mounted file system. df is used to show or find out following information:

1. Used and available space.
2. File system mount points.
3. File system capacity.
4. The number of inodes available.
5. Find of whether there is sufficient space to upgrade or install new apps.

Syntax

The basic syntax is as follows:

df
df /path/to/dev
df [options]
df [options] /path/to/dev

Examples

Type the following command:
# df
# df -H
Sample outputs:

The following example will provide information only for the partition/device that contains the /home directory:
# df /home
# df -h /home
To see inode usage instead of block usage, type:
# df -i
# df -i /
# df -ih /
# df -i /dev/md0
Sample outputs:

Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/md0             7872512   35813 7836699    1% /

Pass the -T to find out file system type:
# df -T -h
Sample outputs:

Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/md0      ext4    119G  1.8G  111G   2% /
tmpfs        tmpfs   1002M     0 1002M   0% /lib/init/rw
udev         tmpfs   1000M  260K 1000M   1% /dev
tmpfs        tmpfs   1002M     0 1002M   0% /dev/shm
/dev/md2      ext4    1.5T  658G  745G  47% /data
/dev/mapper/cryptvg-mybackup
              ext3    591G   78G  484G  14% /securebackup

df command options

From the df command man page:

  -a, --all             include dummy file systems
  -B, --block-size=SIZE  use SIZE-byte blocks
      --total           produce a grand total
  -h, --human-readable  print sizes in human readable format (e.g., 1K 234M 2G)
  -H, --si              likewise, but use powers of 1000 not 1024
  -i, --inodes          list inode information instead of block usage
  -k                    like --block-size=1K
  -l, --local           limit listing to local file systems
      --no-sync         do not invoke sync before getting usage info (default)
  -P, --portability     use the POSIX output format
      --sync            invoke sync before getting usage info
  -t, --type=TYPE       limit listing to file systems of type TYPE
  -T, --print-type      print file system type
  -x, --exclude-type=TYPE   limit listing to file systems not of type TYPE