/usr/lib/xen-common/bin/xen-version is in xen-utils-common 4.1.4-3+deb7u9.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31  | #!/bin/sh -e
error() {
    echo "ERROR: " "$@" >&2
    exit 1
}
if [ -e "/sys/hypervisor/type" ]; then
    type="$(cat /sys/hypervisor/type)"
    if [ "$type" = xen ]; then
        DIR=/sys/hypervisor/version
        VERSION_EXTRA="$(cat $DIR/extra)"
        if [ "$VERSION_EXTRA" = "-unstable" ]; then
            # Old xen-unstable
            VERSION=unstable
        elif [ "$VERSION_EXTRA" != "${VERSION_EXTRA#-}" ]; then
            # ABI for Lenny and smaller
            VERSION="$(cat $DIR/major).$(cat $DIR/minor)$VERSION_EXTRA"
        else
            VERSION="$(cat $DIR/major).$(cat $DIR/minor)"
        fi
    elif [ -z "$type" ]; then
        error "Can't read hypervisor type from sysfs!"
    else
        error "Hypervisor is not xen but '$type'!"
    fi
else
    error "Can't find hypervisor information in sysfs!"
fi
echo "$VERSION"
 |