System and users

`uname`

Print the kernel name, release and version, the hostname, and the machine hardware type.

uname [-asnrvmo]

10 of 10 examples run in Debian 13.7 on 2026-10-31 · coreutils 9.7-3 · manual: uname(1)

uname reports what the running kernel says about itself: its name (Linux, Darwin, FreeBSD), release, build version, the node name (hostname) and the CPU architecture. With no options it prints just the kernel name, which is exactly what a portable script needs to branch on.

It tells you about the kernel, not the distribution. To learn that a machine runs Debian 13 or Ubuntu 24.04, read /etc/os-release. Inside a container, uname -r shows the host's kernel, because containers share it; the examples here run in a Debian container on an Ubuntu host, which is why uname -a shows an Ubuntu kernel build.

Examples

Print the kernel name

$ uname

explain

output

Linux

Plain uname is the same as uname -s. This is the value to test in scripts that must behave differently on Linux and macOS (Darwin).

Print everything at once

$ uname -a

explain

output

Linux demo 6.8.0-138-generic #138-Ubuntu SMP PREEMPT_DYNAMIC Fri Jul 31 22:41:49 UTC 2026 x86_64 GNU/Linux

Kernel name, hostname, release, build version, machine, and on GNU the operating system. This is the line bug reports ask for.

Show the kernel release

$ uname -r

explain

output

6.8.0-138-generic

The release identifies the exact kernel build. It is the name of the directory under /lib/modules that holds that kernel's modules, and the version to match when installing kernel headers.

Show the CPU architecture

$ uname -m

explain

output

x86_64

x86_64 here; ARM machines print aarch64 on Linux and arm64 on macOS. Use this to pick which release binary to download.

Show the hostname

$ uname -n

explain

output

demo

-n prints the network node name, the same value hostname prints; the sandbox's is demo.

Combine fields

$ uname -sr

explain

output

Linux 6.8.0-138-generic

Options can be clustered; fields always come out in a fixed order, whatever order you give them in.

See why -p is not the option you want

$ uname -p -i

explain

output

unknown unknown

On Debian and most Linux distributions the processor and hardware-platform fields are unknown. Use -m for the architecture instead.

Find the distribution, which uname does not tell you

$ . /etc/os-release; echo "$PRETTY_NAME (kernel $(uname -r))"

explain

output

Debian GNU/Linux 13 (trixie) (kernel 6.8.0-138-generic)

/etc/os-release is a shell-syntax file, so sourcing it sets NAME, VERSION_ID, PRETTY_NAME and friends. The distribution is Debian even though uname -a shows an Ubuntu kernel build, because the kernel belongs to the host.

Branch on the OS in a script

$ case "$(uname -s)" in
>   Linux)  echo "using GNU stat"; stat -c '%s bytes' todo.txt ;;
>   Darwin) echo "using BSD stat"; stat -f '%z bytes' todo.txt ;;
>   *)      echo "unsupported: $(uname -s)" >&2; exit 1 ;;
> esac

output

using GNU stat
62 bytes

The kernel name picks the right flavor of a tool whose options differ between GNU and BSD, here stat. The fallback branch fails loudly instead of guessing.

Map the architecture to a download name

$ case "$(uname -m)" in
>   x86_64)        arch=amd64 ;;
>   aarch64|arm64) arch=arm64 ;;
>   *)             arch=unknown ;;
> esac
> echo "would download tool-linux-$arch.tar.gz"

output

would download tool-linux-amd64.tar.gz

Release pages usually say amd64 and arm64 while the kernel says x86_64 and aarch64, so install scripts translate between the two.

Common pitfalls

Using uname -p to detect the architecture. On Linux it is usually unknown; -m is the reliable field.
Expecting uname to identify the distribution. uname -a on Ubuntu, Debian and Fedora all say Linux; read /etc/os-release.
Trusting uname -r inside a container or WSL to describe the image. It reports the kernel the container runs on, which may be a different distribution entirely.

GNU vs BSD and macOS

The examples above ran the GNU/Linux version. These are the differences that matter on macOS and the BSDs (written from their documentation, not run here).

The long options (--kernel-name, --all) and -o/--operating-system are GNU. macOS and BSD uname accept the short letters -a -m -n -p -r -s -v.
On macOS, uname -p gives a real answer (arm or i386) and uname -m gives arm64 or x86_64; on Linux, stick to -m.
uname -a on macOS has no trailing operating-system field; its version string contains the XNU kernel build instead.

Options worth knowing

A selection, described in our own words. For the full list, see uname(1) or uname --help.

Option	What it does
`-a, --all`	Print all fields, skipping -p and -i when they are unknown.
`-s, --kernel-name`	Print the kernel name (the default).
`-n, --nodename`	Print the network node name (hostname).
`-r, --kernel-release`	Print the kernel release.
`-v, --kernel-version`	Print the kernel build version and date.
`-m, --machine`	Print the machine hardware name, such as x86_64.
`-p, --processor`	Print the processor type; often unknown on Linux.
`-i, --hardware-platform`	Print the hardware platform; often unknown on Linux.
`-o, --operating-system`	Print the operating system name, such as GNU/Linux.

Examples

Common pitfalls

GNU vs BSD and macOS

Options worth knowing

Related