For modern Fedora/RHEL-based systems, these commands reveal the distro version:

# Method 1: Check release file
cat /etc/os-release

# Method 2: RedHat-specific (works for RHEL/CentOS/Fedora)
cat /etc/redhat-release

# Method 3: Using hostnamectl (systemd systems)
hostnamectl | grep "Operating System"

When you need precise version matching against legacy systems:
# For Fedora Core 4 detection:
if grep -q "Fedora Core release 4" /etc/redhat-release; then
    echo "This is Fedora Core 4"
fi

# For RHEL/CentOS version check:
rpm -q --qf '%{VERSION}' redhat-release || \
rpm -q --qf '%{VERSION}' centos-release

Here's a robust bash function for version detection:
function get_linux_flavor() {
    if [[ -f /etc/os-release ]]; then
        . /etc/os-release
        echo "$PRETTY_NAME"
    elif [[ -f /etc/redhat-release ]]; then
        cat /etc/redhat-release
    elif [[ -f /etc/centos-release ]]; then
        cat /etc/centos-release
    else
        echo "Unknown distribution"
    fi
}

For containerized environments or minimal installs:
# Check available package manager
if command -v dnf >/dev/null 2>&1; then
    echo "Fedora/RHEL 8+ detected"
elif command -v yum >/dev/null 2>&1; then
    echo "Legacy RHEL/Fedora detected"
fi

For scripting version checks:
# Compare versions in scripts
current_version=$(rpm -E %fedora || rpm -E %rhel)
if [[ $current_version -lt 30 ]]; then
    echo "Older than Fedora 30/RHEL 8"
fi



The most reliable method is to examine the /etc/os-release file, which is standardized across modern Linux distributions:
cat /etc/os-release

Example output for Fedora 38:
NAME="Fedora Linux"
VERSION="38 (Workstation Edition)"
ID=fedora
VERSION_ID=38
VERSION_CODENAME=""
PLATFORM_ID="platform:f38"
PRETTY_NAME="Fedora Linux 38 (Workstation Edition)"

For older systems or specific cases, these commands can help:
Using hostnamectl
hostnamectl | grep -i "operating system"

Checking Red Hat Release Files
cat /etc/redhat-release
cat /etc/fedora-release
cat /etc/centos-release

Example output for CentOS 7:
CentOS Linux release 7.9.2009 (Core)

Here's a bash function to identify your distro:
function get_distro() {
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        echo "$PRETTY_NAME"
    elif [ -f /etc/redhat-release ]; then
        cat /etc/redhat-release
    elif [ -f /etc/fedora-release ]; then
        cat /etc/fedora-release
    elif [ -f /etc/centos-release ]; then
        cat /etc/centos-release
    else
        echo "Unknown distribution"
    fi
}

get_distro

For RPM-based systems, you can query package versions:
rpm -q fedora-release
rpm -q centos-release
rpm -q redhat-release