diff --git a/commonsh/10_utility b/commonsh/10_utility
index 10fde67..0f553cd 100755
--- a/commonsh/10_utility
+++ b/commonsh/10_utility
@@ -4,41 +4,46 @@
 
 unkey_host ()
 {
-   [ ${#} -ne 1 ] && return 1
+   [ $# -ne 1 ] && return 1
    sed -i -e "/$1/d" $HOME/.ssh/known_hosts
 }
 
 err ()
 {
-      case $@ in
+      case $1 in
          E*)
+            errconst=$1
             unset errno
             if [ "${errno}" = "" ] && ( command -v python > /dev/null 2>&1 ); then
-               errno=`python -c "import errno;print(errno.$@)" 2>/dev/null`
+               errno=`python -c "import errno;print(errno.${errconst})" 2>/dev/null`
+            fi
+            if [ "${errno}" = "" ] && ( command -v perl > /dev/null 2>&1 ); then
+               errno=`perl -MErrno -e "print &Errno::${errconst}.\"\n\";" 2>/dev/null`
             fi
             if [ "${errno}" = "" ] && ( command -v ruby > /dev/null 2>&1 ); then
-               errno=`ruby -e "puts Errno::$@::Errno if (Errno::$@)" 2>/dev/null`
+               errno=`ruby -e "puts Errno::${errconst}::Errno" 2>/dev/null`
             fi
             if [ "${errno}" = "" ] && [ -e /usr/include/errno.h ] ; then
-               errno=`cpp -dM /usr/include/errno.h | grep -w "$@" | grep -oE '[0-9]+' 2>/dev/null`
+               errno=`cpp -dM /usr/include/errno.h | grep -E "${errconst}[[:space:]]+[0-9]+$" | grep -oE '[0-9]+' 2>/dev/null`
             fi
 
             if [ "${errno}" ] ; then
-               echo "$@ = $errno"
+               echo "${errconst} = ${errno}"
             else
                return 1
             fi
          ;;
          *)
+            errno=$1
             unset errconst
-            if [ "${errconst}" = "" ] && ( command -v python > /dev/null 2>&1 ); then
-               errconst=`python -c "import errno;print(errno.errorcode[$@])" 2>/dev/null`
-            fi
             if [ "${errconst}" = "" ] && ( command -v ruby > /dev/null 2>&1 ); then
-               errconst=`ruby -e "puts Errno.constants.find_all{|err| eval('Errno::' + err + '::Errno') == $@ }"`
+               errconst=`ruby -e "puts Errno.constants.find_all{|err| eval('Errno::' + err + '::Errno') == ${errno} }, ' = ${errno}'" 2>/dev/null`
+            fi
+            if [ "${errconst}" = "" ] && ( command -v python > /dev/null 2>&1 ); then
+               errconst=`python -c "import errno;print(errno.errorcode[${errno}] + ' = ${errno}')" 2>/dev/null`
             fi
             if [ "${errconst}" = "" ] && [ -e /usr/include/errno.h ] ; then
-               errconst=`cpp -dM /usr/include/errno.h | grep -w "E.* $@"`
+               errconst=`cpp -dM /usr/include/errno.h | grep -E "E[[:alnum:]]+[[:space:]]+${errno}$"`
             fi
 
             if [ "${errconst}" ] ; then
@@ -46,15 +51,21 @@ err ()
             else
                return 1
             fi
-
-            errno=$@
          ;;
    esac
 
-   if ( command -v perl > /dev/null 2>&1 ) ; then
-      perl -MPOSIX -e 'print strerror($ARGV[0])."\n";' $errno
-   elif ( command -v python > /dev/null 2>&1 ) ; then
-      python -c "import os;print(os.strerror($errno))"
+   unset errstr
+   if [ "${errstr}" = "" ] && ( command -v perl > /dev/null 2>&1 ) ; then
+      errstr=`perl -MPOSIX -e 'print strerror($ARGV[0])."\n";' $errno`
+   fi
+   if [ "${errstr}" = "" ] && ( command -v python > /dev/null 2>&1 ) ; then
+      errstr=`python -c "import os;print(os.strerror($errno))" 2>/dev/null`
+   fi
+
+   if [ "${errstr}" ] ; then
+      echo $errstr
+   else
+      return 2
    fi
 }
 
@@ -70,13 +81,13 @@ mkcd ()
 
 extract ()
 {
-   if ( command -v aunpack > /dev/null 2>&1 ) ; then
-      aunpack "${1}"
+   if [ ! -f "$1" ] ; then
+      echo "The file ("$1") does not exist!"
       return
    fi
 
-   if [ ! -f "$1" ] ; then
-      echo "The file ("$1") does not exist!"
+   if ( command -v aunpack > /dev/null 2>&1 ) ; then
+      aunpack "${1}"
       return
    fi