gistfile1

function rat {
 # change part of pwd path, and cd to it
 # example:
 # /usr/lib/foo$ rat li src
 # /usr/src/foo$
 local cd=$(echo $PWD | awk -v q="$*" -F\/ '
  BEGIN { l = split(q,a," ") }
  {
   for( i=1;i<=NF;i++ ) {
    for( j=1;j<=l;j=j+2 ) {
     if( !a[j] || $i !~ a[j] ) continue
     $i = a[j+1]
     delete a[j]
    }
   }
   for( i=1;i<=NF;i++ ) printf $i "/"
  }
 ')
 [ -d "$cd" ] && cd $cd
}