Hola a todos tengo el siguiente error al instalar postgis en centos me sale el siguiente error

[root@localhost postgis-1.3.6]# ./configure checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking for g++... g++ checking whether we are using the GNU C++ compiler... yes checking whether g++ accepts -g... yes checking whether ln -s works... yes checking for iconv_open in -liconv... no checking for libiconv_open in -liconv... no checking for iconv_open in -lc... yes checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking iconv.h usability... yes checking iconv.h presence... yes checking for iconv.h... yes checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking for pg_config... no configure: error: PostgreSQL is required by PostGIS [root@localhost postgis-1.3.6]# ./configure checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking for g++... g++ checking whether we are using the GNU C++ compiler... yes checking whether g++ accepts -g... yes checking whether ln -s works... yes checking for iconv_open in -liconv... no checking for libiconv_open in -liconv... no checking for iconv_open in -lc... yes checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking iconv.h usability... yes checking iconv.h presence... yes checking for iconv.h... yes checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking for pg_config... no configure: error: PostgreSQL is required by PostGIS

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