$ sudo port clean qgis
Password:
--->  Cleaning QGIS
$ sudo port install qgis
--->  Computing dependencies for QGIS
--->  Fetching archive for QGIS
--->  Attempting to fetch QGIS-2_18_2_2+postgresql96+qt4.darwin_14.x86_64.tbz2 from http://nou.nc.packages.macports.org/pub/macports/packages.macports.org/QGIS
--->  Attempting to fetch QGIS-2_18_2_2+postgresql96+qt4.darwin_14.x86_64.tbz2 from https://packages.macports.org/QGIS
--->  Attempting to fetch QGIS-2_18_2_2+postgresql96+qt4.darwin_14.x86_64.tbz2 from http://sea.us.packages.macports.org/macports/packages/QGIS
--->  Fetching distfiles for QGIS
--->  Verifying checksums for QGIS
--->  Extracting QGIS
--->  Applying patches to QGIS
--->  Configuring QGIS
Error: Failed to configure QGIS: configure failure: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_gis_qgis/QGIS/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port qgis failed