--- a/.bashrc	Mon Jan 02 17:57:42 2012 +0200
+++ b/.bashrc	Mon Jan 02 18:04:24 2012 +0200
@@ -131,18 +131,20 @@
   umask 0000
 fi
 
-export PATH=$PATH:~/usr/bin
+if [[ ! $PATH =~ $HOME/usr/bin ]]; then
+  export PATH=$PATH:~/usr/bin
+fi
 
 if [[ -z "$MANPATH" ]]; then
   export MANPATH=~/usr/share/man:
-else
-  export MANPATH=$MANPATH:~/usr/share/man:
+elif [[ ! $MANPATH =~ $HOME/usr/share/man: ]]; then
+  export MANPATH=$MANPATH:$HOME/usr/share/man:
 fi
 
 if [[ -z "$INFOPATH" ]]; then
   export INFOPATH=~/usr/share/info:
-else
-  export INFOPATH=$INFOPATH:~/usr/share/info:
+elif [[ ! $INFOPATH =~ $HOME/usr/share/info: ]]; then
+  export INFOPATH=$INFOPATH:$HOME/usr/share/info:
 fi
 
 export PYTHONSTARTUP=~/.pystartup