How do I check how much free space left on a device to create a partition

Question

Let's say I have this virtual machine running:

[root@centos ~]# fdisk -ul

Disk /dev/sda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders, total 16777216 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63      417689      208813+  83  Linux
/dev/sda2         2522205    13799834     5638815   83  Linux
/dev/sda3        13799835    16771859     1486012+  8e  Linux LVM
/dev/sda4          417690     2522204     1052257+   5  Extended
/dev/sda5          417753     2522204     1052226   82  Linux swap /     Solaris

How can I know how much free space left for more partitions on the disk?

Solution 1

As root, type in a shell:

# cfdisk /dev/sdX  #Where /dev/sdX is the device 

it will show you something like this:

cfdisk (util-linux-ng 2.18)

                          Disk Drive: /dev/sdb
                    Size: 3926949888 bytes, 3926 MB
          Heads: 255   Sectors per Track: 63   Cylinders: 477

Name        Flags      Part Type  FS Type          [Label]        Size (MB)

---

sdb1                    Primary   vfat             [ABDEL]          1998.75
sdb2        Boot        Primary   ext3             [linx]           1924.72

if the device has free space it will be shown.

Note: cfdisk in fact is a terminal based partition editor.

Solution 2

You could also use parted in command mode:

parted /dev/sda unit MiB print free

output:

Model: ATA M4-CT128M4SSD2 (scsi)
Disk /dev/sda: 122104MiB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start     End        Size      Type     File system     Flags
        0.03MiB   1.00MiB    0.97MiB            Free Space
 1      1.00MiB   28672MiB   28671MiB  primary  ext4
        28672MiB  28673MiB   1.00MiB            Free Space
 2      28673MiB  30720MiB   2047MiB   primary  linux-swap(v1)
        30720MiB  30721MiB   1.00MiB            Free Space
 3      30721MiB  92160MiB   61439MiB  primary  ntfs
        92160MiB  122104MiB  29944MiB           Free Space

If you want just the total free space you could run:

parted /dev/sda unit MiB print free | awk '/Free Space/{c++; sum += $3} \
END{if(c == 0) print "No Free Space"; else print sum" MiB"}'
29947 MiB

You can use different units to display the size: B up to TB, KiB up to TiB etc (see man parted for details).

Solution 3

To report all drives/partitions and their remaining sizes:

df -h

or:

fdisk -l

For folders use the disk usage command with the -sh options:

du -sh

Note: -h is for showing human readable (i.e. 34 GB instead of 340000000 blocks/bytes)

Comments

[Martin Scharrer]

With "free space" you mean "not yet allocated to a partition" aka "unpartitioned space", do you? The v command of fdisk verifies the partition table and reports such space as well, e.g. Remaining 239 unallocated 512-byte sectors in my case.

[Chen A.]

that's exactly what I meant. but the -v command means: Print version number of fdisk and exit.

[Martin Scharrer]

I'm talking about the v command, not the -v command line option, i.e. you need to start fdisk /dev/sda in interactive mode and then type v<ENTER>.

[tcoolspy]

You could use cfdisk -P s /dev/sdX to print out the partition table to the console without entering the interactive partition editor. If you do enter it as @abdelfatah directs, you can exit by pressing 'q'.