How to Get Linux Distribution Name and Version in a Shell Script

distributionslinuxshell-script

I'm working on a simple bash script that should be able to run on Ubuntu and CentOS distributions (support for Debian and Fedora/RHEL would be a plus) and I need to know the name and version of the distribution the script is running (in order to trigger specific actions, for instance the creation of repositories). So far what I've got is this:

OS=$(awk '/DISTRIB_ID=/' /etc/*-release | sed 's/DISTRIB_ID=//' | tr '[:upper:]' '[:lower:]')
ARCH=$(uname -m | sed 's/x86_//;s/i[3-6]86/32/')
VERSION=$(awk '/DISTRIB_RELEASE=/' /etc/*-release | sed 's/DISTRIB_RELEASE=//' | sed 's/[.]0/./')

if [ -z "$OS" ]; then
    OS=$(awk '{print $1}' /etc/*-release | tr '[:upper:]' '[:lower:]')
fi

if [ -z "$VERSION" ]; then
    VERSION=$(awk '{print $3}' /etc/*-release)
fi

echo $OS
echo $ARCH
echo $VERSION

This seems to work, returning ubuntu or centos (I haven't tried others) as the release name. However, I have a feeling that there must be an easier, more reliable way of finding this out — is that true?

It doesn't work for RedHat.
/etc/redhat-release contains :
Redhat Linux Entreprise release 5.5

So, the version is not the third word, you'd better use :

OS_MAJOR_VERSION=`sed -rn 's/.*([0-9])\.[0-9].*/\1/p' /etc/redhat-release`
OS_MINOR_VERSION=`sed -rn 's/.*[0-9].([0-9]).*/\1/p' /etc/redhat-release`
echo "RedHat/CentOS $OS_MAJOR_VERSION.$OS_MINOR_VERSION"

Best Answer

To get OS and VER, the latest standard seems to be /etc/os-release. Before that, there was lsb_release and /etc/lsb-release. Before that, you had to look for different files for each distribution.

Here's what I'd suggest

if [ -f /etc/os-release ]; then
    # freedesktop.org and systemd
    . /etc/os-release
    OS=$NAME
    VER=$VERSION_ID
elif type lsb_release >/dev/null 2>&1; then
    # linuxbase.org
    OS=$(lsb_release -si)
    VER=$(lsb_release -sr)
elif [ -f /etc/lsb-release ]; then
    # For some versions of Debian/Ubuntu without lsb_release command
    . /etc/lsb-release
    OS=$DISTRIB_ID
    VER=$DISTRIB_RELEASE
elif [ -f /etc/debian_version ]; then
    # Older Debian/Ubuntu/etc.
    OS=Debian
    VER=$(cat /etc/debian_version)
elif [ -f /etc/SuSe-release ]; then
    # Older SuSE/etc.
    ...
elif [ -f /etc/redhat-release ]; then
    # Older Red Hat, CentOS, etc.
    ...
else
    # Fall back to uname, e.g. "Linux <version>", also works for BSD, etc.
    OS=$(uname -s)
    VER=$(uname -r)
fi

I think uname to get ARCH is still the best way. But the example you gave obviously only handles Intel systems. I'd either call it BITS like this:

case $(uname -m) in
x86_64)
    BITS=64
    ;;
i*86)
    BITS=32
    ;;
*)
    BITS=?
    ;;
esac

Or change ARCH to be the more common, yet unambiguous versions: x86 and x64 or similar:

case $(uname -m) in
x86_64)
    ARCH=x64  # or AMD64 or Intel64 or whatever
    ;;
i*86)
    ARCH=x86  # or IA32 or Intel32 or whatever
    ;;
*)
    # leave ARCH as-is
    ;;
esac

but of course that's up to you.

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