$ sudo port -f install MacPorts

[Charlse Darwin]

$ sudo port -f install MacPorts
Portfile changed since last build; discarding previous state.
--->  Fetching MacPorts
--->  Attempting to fetch MacPorts-1.6.0.tar.gz from http:// 
svn.macports.org/repository/macports/distfiles/MacPorts-1.6.0
--->  Attempting to fetch MacPorts-1.6.0.tar.gz from http:// 
svn.macports.org/repository/macports/distfiles/general/MacPorts-1.6.0
--->  Attempting to fetch MacPorts-1.6.0.tar.gz from http:// 
svn.macports.org/repository/macports/downloads/MacPorts-1.6.0
--->  Verifying checksum(s) for MacPorts
--->  Extracting MacPorts
--->  Configuring MacPorts
Fixing your MacOSX10.4u installation by copying libtclstub8.4.a to / 
Developer/SDKs/MacOSX10.4u.sdk/System/Library/Frameworks/ 
Tcl.framework/Versions/8.4/libtclstub8.4.a
Error: Target org.macports.configure returned: configure failure:  
shell command " cd "/opt/local/var/macports/build/ 
_opt_local_var_macports_sources_rsync.macports.org_release_ports_sysutil 
s_MacPorts/work/MacPorts-1.6.0" && ./configure --prefix=/opt/local -- 
enable-readline " returned error 1
Command output: configure: error: cannot run /bin/sh ./config.sub

Error: Status 1 encountered during processing.
$