uname Command

Display system information including kernel name, version, and architecture

Syntax: uname [OPTION]...

Description

The uname command displays system information about the current machine and operating system. It provides details such as the kernel name, network node hostname, kernel release, kernel version, machine hardware name, processor type, hardware platform, and operating system name.

Note: Without any options, uname displays the kernel name (equivalent to uname -s). This command is commonly used in scripts to determine system characteristics.

Common Options

Option	Description
`-a, --all`	Print all information (equivalent to -snrvmpio)
`-s, --kernel-name`	Print the kernel name
`-n, --nodename`	Print the network node hostname
`-r, --kernel-release`	Print the kernel release
`-v, --kernel-version`	Print the kernel version
`-m, --machine`	Print the machine hardware name
`-p, --processor`	Print the processor type
`-i, --hardware-platform`	Print the hardware platform
`-o, --operating-system`	Print the operating system
`--help`	Display help message and exit
`--version`	Output version information and exit

Examples

Basic usage (kernel name):

uname
# Output: Linux

uname -s
# Output: Linux (same as above)

Display all system information:

uname -a
# Output: Linux hostname 5.15.0-56-generic #62-Ubuntu SMP Tue Nov 22 19:54:14 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Display kernel release:

uname -r
# Output: 5.15.0-56-generic

uname --kernel-release
# Output: 5.15.0-56-generic

Display machine architecture:

uname -m
# Output: x86_64

uname --machine
# Output: x86_64

Display hostname:

uname -n
# Output: myserver

uname --nodename
# Output: myserver

Display kernel version:

uname -v
# Output: #62-Ubuntu SMP Tue Nov 22 19:54:14 UTC 2022

Display operating system:

uname -o
# Output: GNU/Linux

uname --operating-system
# Output: GNU/Linux

Display processor information:

uname -p
# Output: x86_64 (or unknown on some systems)

uname -i
# Output: x86_64 (hardware platform)

Combine multiple options:

uname -sr
# Output: Linux 5.15.0-56-generic

uname -nm
# Output: myserver x86_64

uname -rmo
# Output: 5.15.0-56-generic x86_64 GNU/Linux

Output Format Explanation

When using uname -a, the output format is:

Sample output breakdown:

Linux hostname 5.15.0-56-generic #62-Ubuntu SMP Tue Nov 22 19:54:14 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Fields in order:

Kernel name: Linux
Hostname: hostname
Kernel release: 5.15.0-56-generic
Kernel version: #62-Ubuntu SMP Tue Nov 22 19:54:14 UTC 2022
Machine: x86_64
Processor: x86_64
Hardware platform: x86_64
Operating system: GNU/Linux

Common Architecture Values

Architecture	Description
`x86_64`	64-bit Intel/AMD processors
`i386`, `i686`	32-bit Intel processors
`aarch64`	64-bit ARM processors
`armv7l`	32-bit ARM processors
`ppc64le`	64-bit PowerPC (little endian)
`s390x`	IBM System z (64-bit)
`mips64`	64-bit MIPS processors

Practical Usage in Scripts

Check architecture in scripts:

#!/bin/bash
ARCH=$(uname -m)
if [ "$ARCH" = "x86_64" ]; then
    echo "64-bit system detected"
    # Download 64-bit version
elif [ "$ARCH" = "i386" ] || [ "$ARCH" = "i686" ]; then
    echo "32-bit system detected"
    # Download 32-bit version
else
    echo "Unsupported architecture: $ARCH"
fi

Check operating system:

#!/bin/bash
OS=$(uname -s)
case $OS in
    Linux)
        echo "Running on Linux"
        ;;
    Darwin)
        echo "Running on macOS"
        ;;
    FreeBSD)
        echo "Running on FreeBSD"
        ;;
    *)
        echo "Unknown operating system: $OS"
        ;;
esac

Create system information report:

#!/bin/bash
echo "System Information Report"
echo "========================"
echo "Hostname: $(uname -n)"
echo "Operating System: $(uname -o)"
echo "Kernel: $(uname -s) $(uname -r)"
echo "Architecture: $(uname -m)"
echo "Kernel Version: $(uname -v)"
echo "Full Info: $(uname -a)"

Conditional compilation based on architecture:

#!/bin/bash
ARCH=$(uname -m)
KERNEL=$(uname -r)

echo "Compiling for architecture: $ARCH"
echo "Kernel version: $KERNEL"

if [[ $ARCH == "x86_64" ]]; then
    CFLAGS="-m64 -O2"
elif [[ $ARCH == "i"*"86" ]]; then
    CFLAGS="-m32 -O2"
else
    CFLAGS="-O2"
fi

echo "Using CFLAGS: $CFLAGS"

Advanced Usage

Format output for specific needs:

# Get just the major kernel version
uname -r | cut -d. -f1-2
# Output: 5.15

# Check if running specific kernel version
if [[ $(uname -r) == *"generic"* ]]; then
    echo "Running Ubuntu generic kernel"
fi

# Get hostname without domain
uname -n | cut -d. -f1

Compare with other system info commands:

# uname vs other commands
echo "uname -n: $(uname -n)"
echo "hostname: $(hostname)"
echo "uname -r: $(uname -r)"
echo "uname -m: $(uname -m)"
echo "arch: $(arch)"  # equivalent to uname -m

Use in Makefiles:

# Makefile example
UNAME_S := $(shell uname -s)
UNAME_M := $(shell uname -m)

ifeq ($(UNAME_S),Linux)
    CCFLAGS += -D LINUX
endif
ifeq ($(UNAME_S),Darwin)
    CCFLAGS += -D OSX
endif
ifeq ($(UNAME_M),x86_64)
    CCFLAGS += -D AMD64
endif

Common Use Cases

System identification: Determining the operating system and architecture
Script portability: Writing scripts that work across different systems
Software installation: Selecting appropriate binaries for the system
System monitoring: Including system info in logs and reports
Debugging: Identifying system characteristics when troubleshooting
Conditional compilation: Setting compiler flags based on architecture
Documentation: Recording system specifications
Automation: Making deployment scripts system-aware

Tips and Best Practices

Use uname -a for comprehensive system information
Store uname output in variables for multiple uses in scripts
Use uname -m to detect 32-bit vs 64-bit systems
Combine with other commands like lsb_release for complete OS info
Be aware that some fields may show "unknown" on certain systems
Use case statements for handling multiple OS types
Consider using arch command as alternative to uname -m
Test scripts on different architectures when using uname for conditionals

Related Information

Command	Purpose
`hostname`	Display or set system hostname
`arch`	Display machine architecture (same as uname -m)
`lsb_release`	Display Linux distribution information
`cat /proc/version`	Display detailed kernel version information
`hostnamectl`	Control system hostname and related settings

Related Commands: hostname, lscpu, arch, hostnamectl, lsb_release

Linux Commands