On some systems with shared libraries you need to tell the system how to find the newly installed shared libraries. The systems on which this is not necessary include FreeBSD, Linux, NetBSD, OpenBSD, and Solaris.
    The method to set the shared library search path varies between
    platforms, but the most widely-used method is to set the
    environment variable LD_LIBRARY_PATH like so: In Bourne
    shells (sh, ksh, bash, zsh):
LD_LIBRARY_PATH=/usr/local/pgsql/lib export LD_LIBRARY_PATH
    or in csh or tcsh:
setenv LD_LIBRARY_PATH /usr/local/pgsql/lib
    Replace /usr/local/pgsql/lib with whatever you set
    --libdir/etc/profile or ~/.bash_profile.  Some
    good information about the caveats associated with this method can
    be found at http://xahlee.info/UnixResource_dir/_/ldpath.html.
   
    On some systems it might be preferable to set the environment
    variable LD_RUN_PATH before
    building.
   
    On Cygwin, put the library
    directory in the PATH or move the
    .dll files into the bin
    directory.
   
    If in doubt, refer to the manual pages of your system (perhaps
    ld.so or rld). If you later
    get a message like:
psql: error in loading shared libraries libpq.so.2.1: cannot open shared object file: No such file or directory
then this step was necessary. Simply take care of it then.
If you are on Linux and you have root access, you can run:
/sbin/ldconfig /usr/local/pgsql/lib
    (or equivalent directory) after installation to enable the
    run-time linker to find the shared libraries faster.  Refer to the
    manual page of ldconfig for more information.  On
    FreeBSD, NetBSD, and OpenBSD the command is:
/sbin/ldconfig -m /usr/local/pgsql/lib
instead. Other systems are not known to have an equivalent command.
    If you installed into /usr/local/pgsql or some other
    location that is not searched for programs by default, you should
    add /usr/local/pgsql/bin (or whatever you set
    --bindirPATH.  Strictly speaking, this is not
    necessary, but it will make the use of PostgreSQL
    much more convenient.
   
    To do this, add the following to your shell start-up file, such as
    ~/.bash_profile (or /etc/profile, if you
    want it to affect all users):
PATH=/usr/local/pgsql/bin:$PATH export PATH
    If you are using csh or tcsh, then use this command:
set path = ( /usr/local/pgsql/bin $path )
To enable your system to find the man documentation, you need to add lines like the following to a shell start-up file unless you installed into a location that is searched by default:
MANPATH=/usr/local/pgsql/share/man:$MANPATH export MANPATH
    The environment variables PGHOST and PGPORT
    specify to client applications the host and port of the database
    server, overriding the compiled-in defaults. If you are going to
    run client applications remotely then it is convenient if every
    user that plans to use the database sets PGHOST.  This
    is not required, however; the settings can be communicated via command
    line options to most client programs.