Disallow use of unset variables

[virt-what.git] / virt-what.in

diff --git a/virt-what.in b/virt-what.in
index 4f381ab..d62f7c8 100644 (file)
--- a/virt-what.in
+++ b/virt-what.in
@@ -26,6 +26,11 @@
 # The following resources were useful in writing this script:
 # . http://www.dmo.ca/blog/20080530151107
 
+# Do not allow unset variables, and set defaults.
+set -u
+root=''
+skip_qemu_kvm=false
+
 VERSION="@VERSION@"
 
 function fail {
@@ -43,7 +48,7 @@ function usage {
 
 # Handle the command line arguments, if any.
 
-TEMP=`getopt -o v --long help --long version --long test-root: -n 'virt-what' -- "$@"`
+TEMP=$(getopt -o v --long help --long version --long test-root: -n 'virt-what' -- "$@")
 if [ $? != 0 ]; then exit 1; fi
 eval set -- "$TEMP"
 
@@ -78,19 +83,19 @@ fi
 # Many fullvirt hypervisors give an indication through CPUID.  Use the
 # helper program to get this information.
 
-cpuid=`virt-what-cpuid-helper`
+cpuid=$(virt-what-cpuid-helper)
 
 # Check for various products in the BIOS information.
 # Note that dmidecode doesn't exist on non-PC architectures.  On these,
 # this will return an error which is ignored (error message redirected
 # into $dmi variable).
 
-dmi=`LANG=C dmidecode 2>&1`
+dmi=$(LANG=C dmidecode 2>&1)
 
 # Architecture.
 # Note for the purpose of testing, we only call uname with -p option.
 
-arch=`uname -p`
+arch=$(uname -p)
 
 # Check for VMware.
 # cpuid check added by Chetan Loke.
@@ -171,14 +176,14 @@ fi
 # Check for Parallels.
 if echo "$dmi" | grep -q 'Vendor: Parallels'; then
     echo parallels
-    skip_qemu_kvm=1
+    skip_qemu_kvm=true
 fi
 
 # Check for Xen.
 
 if [ "$cpuid" = "XenVMMXenVMM" ]; then
     echo xen; echo xen-hvm
-    skip_qemu_kvm=1
+    skip_qemu_kvm=true
 elif [ -f $root/proc/xen/capabilities ]; then
     echo xen
     if grep -q "control_d" $root/proc/xen/capabilities; then
@@ -186,7 +191,7 @@ elif [ -f $root/proc/xen/capabilities ]; then
     else
         echo xen-domU
     fi
-    skip_qemu_kvm=1
+    skip_qemu_kvm=true
 elif [ -f $root/sys/hypervisor/type ] &&
     grep -q "xen" $root/sys/hypervisor/type; then
     # Ordinary kernel with pv_ops.  There does not seem to be
@@ -217,7 +222,7 @@ fi
 # seen that it's Parallels.  Xen uses QEMU as the device model, so
 # skip this test if we know it is Xen.
 
-if [ ! "$skip_qemu_kvm" ]; then
+if ! $skip_qemu_kvm; then
     if [ "$cpuid" = "KVMKVMKVM" ]; then
        echo kvm
     else