Si al actualizar o modificar los paquetes instalados en Ubuntu ocurre el siguiente error:
(...)
Setting up libcap2-bin (1:2.19-2) ...
/var/lib/dpkg/info/libcap2-bin.postinst: line 23: pam-auth-update: command not found
dpkg: error processing libcap2-bin (--configure):
subprocess installed post-installation script returned error exit status 127
Errors were encountered while processing:
libcap2-bin
E: Sub-process /usr/bin/dpkg returned an error code (1)
(...)
Al no disponerse habitualmente el comando «pam-auth-update» (deprecated), es facilmente solucionable bypasseandolo.
$ ln -s /bin/true /usr/local/bin/pam-auth-update
Fuente: OsDir