1. Introduction

For administration tasks, we often need detailed information about our system. Thus in the Linux case, the knowledge about kernel version and distribution is very basic for us.

Moreover, we need information about the physical storage available. Consequently, in the Linux context, we need to list disk partitions.

We’re going to look through Linux commands helpful to achieve this goal.

2. The uname Command for Kernel Data

The uname command returns a bunch of information concerning our kernel. So, let’s check the kernel name:

$ uname

2.1. Options to uname

We should use options to get more specific information. Therefore, for all fields, let’s use the –a switch:

$ uname -a
Linux 5.14.10-300.fc35.x86_64 #1 SMP Thu Oct 7 20:48:44 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Now, let’s check each kernel-related piece of information with its own switch.

Thus, for the kernel name, let’s use -s (or just nothing):

$ uname -s

Then, for the kernel release, let’s use -r:

$ uname -r

Finally, for the kernel version, we should use -v:

$ uname -v
#1 SMP Thu Oct 7 20:48:44 UTC 2021

Let’s notice that, the kernel-related data are just compiled during the build of the kernel. In the runtime, they are obtained with the uname system call.

2.2. Availability

The command is a part of the sh-utils or coreutils package. Therefore, we should find it in almost all distributions.

3. Distribution Information With lsb_release

Now we’re going to learn about the Linux distribution details with the lsb_release command:

$ lsb_release -a
LSB Version:	:core-4.1-amd64:core-4.1-noarch
Distributor ID:	Fedora
Description:	Fedora release 35 (Thirty Five)
Release:	35
Codename:	ThirtyFive

So, we see that our operating system is Fedora 35.

Furthermore, let’s notice that the command is built around the Linux Standard Base (LSB) concept.

Thus, in the case of LSB compliant distributions, the command gathers information from /etc/lsb-release and /etc/distrib-release files. In addition, it parses the names of files in the /etc/lsb-release.d folder.

However, in our Fedora 35 example, only the folder /etc/lsb-release.d exists.

In certain distributions, the command is not available out of the box. It comes with the lsb_release package.

4. Parsing the os-release File

We can achieve a similar effect as using lsb_release by parsing the content of the /etc/os-release file. So, let’s cat it:

$ cat /etc/os-release
NAME="Fedora Linux"
VERSION="35 (Workstation Edition)"
PRETTY_NAME="Fedora Linux 35 (Workstation Edition)"
# more output skipped ...

Now, let’s be more specific and display only PRETTY_NAME with the help of grep:

$ grep '^PRETTY_NAME' /etc/os-release
PRETTY_NAME="Fedora Linux 35 (Workstation Edition)"

This feature is a part of the systemd manager, so we should find it in most Linux distributions. However, not all fields need to be filled.

5. The hostnamectl Command

The hostnamectl command manages the hostnames of the system. It accepts commands related to different features of the system.

Thus, with the status command, we’re going to obtain information on kernel and distribution:

$ hostnamectl status
   Static hostname: n/a
Transient hostname:
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 588ce19ba22340289d4e9f9ad3c5df63
           Boot ID: 5a4584a74a1f4b1596ac4b6d15c96e01
    Virtualization: oracle
  Operating System: Fedora Linux 35 (Workstation Edition)
       CPE OS Name: cpe:/o:fedoraproject:fedora:35
            Kernel: Linux 5.14.10-300.fc35.x86_64
      Architecture: x86-64
   Hardware Vendor: innotek GmbH
    Hardware Model: VirtualBox

Although some other commands narrow the hostnamectl‘s output, no one returns sole kernel information.

The hostnamectl command comes with the systemd-services package.

6. Listing Block Devices With lsblk

We’re going to obtain information about the system’s block devices with the lsblk command:

sda    sda                      78,1G
├─sda1 sda1  ext2   /boot        1,5G
├─sda2 sda2                        1K
├─sda5 sda5  ext4   /            5,5G
├─sda6 sda6  ext4   /usr        12,5G
├─sda7 sda7  ext4   /home       54,7G
└─sda8 sda8  swap                  4G
sr0    sr0                      1024M

We should use -o options to provide the list of column names we want to display. In our example, we used:

  • NAME – device name
  • KNAME – internal device name
  • FSTYPE – the type of filesystem
  • MOUNPOINT – the mounting point of the device
  • SIZE – device’s size

We can obtain the complete list of available columns using issuing lsblk -h.

In addition, we can change units to bytes with the -b switch.

Finally, we don’t need the root privilege to run this command. However, without root access or sudo, some columns aren’t available, e.g., FSTYPE.

The command is distributed as a part of the util-linux package.

7. Listing Disk Partitions With fdisk

Let’s use the well-known fdisk command to list the disk’s partition:

$ sudo fdisk -l

Disk /dev/sda: 83.9 GB, 83886080000 bytes
255 heads, 63 sectors/track, 10198 cylinders, total 163840000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000031b3

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     3106815     1552384   83  Linux
/dev/sda2         3108864   163839999    80365568    5  Extended
/dev/sda5         3110912    14583807     5736448   83  Linux
/dev/sda6        14585856    40724479    13069312   83  Linux
/dev/sda7        40726528   155449343    57361408   83  Linux
/dev/sda8       155451392   163839999     4194304   82  Linux swap / Solaris

The size of partitions is given in 512-byte blocks. Unfortunately, we can’t change the unit shown on the list.

7.1. Getting the Partition’s Size in GB

Let’s display partition details, passing its name as an argument to fdisk:

$ sudo fdisk -l /dev/sda7

Disk /dev/sda7: 58.7 GB, 58738081792 bytes
255 heads, 63 sectors/track, 7141 cylinders, total 114722816 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sda7 doesn't contain a valid partition table

In this way, we can read the partition size in GB.

7.2. Security Remarks and Availability

We should be aware that providing the partitions list is only a small part of the fdisk‘s capabilities.

Primarily, it’s an interactive tool to create, delete, and modify partitions.

So, if by accident we call sudo fdisk /dev/sda (without -l), then we get into a shell with all fdisk‘s commands available.

Then, if we don’t want to change the partition table, we should type q to quit.

The command is included in the util-linux package.

8. parted to Cope With Big Partitions

Yet another command to manipulate partitions is parted. So, let’s show the usual list of partitions:

$ sudo parted -l
Disk /dev/sda: 83,9GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system     Flags
 1      1049kB  1591MB  1590MB  primary   ext2            boot
 2      1592MB  83,9GB  82,3GB  extended
 5      1593MB  7467MB  5874MB  logical   ext4
 6      7468MB  20,9GB  13,4GB  logical   ext4
 7      20,9GB  79,6GB  58,7GB  logical   ext4
 8      79,6GB  83,9GB  4295MB  logical   linux-swap(v1)

Let’s notice that the partitions are identified by number, not by the device name. In addition, the size is neatly formatted with the appropriate unit.

The parted command is an interactive tool similar to fdisk.

However, its remarkable feature is the ability to deal with partitions greater than 2 TB.

We need to install this utility from the equally named package parted.

9. Conclusion

In this article, we presented ways to provide information about the Linux operating system. We started with retrieving the compiled-in kernel version.

Next, we learned how to check the Linux distribution details by applying the LSB concept or using systemd data. We also retrieved similar information by means of the hostnames managing tool.

Finally, we examined a variety of tools destined to query the disk’s partitions system.

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