stored procedure from oracle to pgsql

Dear,
I'm new in pgsql, come from oracle and sql server.
any one can help by transferring a pl/sql procedure that imports data from a flat file, using UTL_FILE, and inserts or
updatestables. 
bellow the proc:

CREATE OR REPLACE Procedure UPD is
    sOracleMsg              varchar2(512);
    sCustomerMsg            varchar2(100);
    fHandle UTL_FILE.FILE_Type;
    sPath                   varchar2(200)   := '/home';
    sfile                   varchar2(30)    := 'prod_2903.txt';
    sBuffer                 varchar2(4000);
    contract                vertraege."Vertrags_Nr"%TYPE;
    phone                    vertraege."Phone"%TYPE;
    status                   vertraege."Status"%TYPE;
   -- Declare program variables as shown above
BEGIN
    fHandle := UTL_FILE.FOPEN(sPath, '/'||sfile, 'r');
    IF UTL_FILE.Is_OPEN(fHandle) THEN
        loop
            begin
                UTL_FILE.GET_LINE(fHandle, sBuffer);
                        phone := substr(sBuffer,1,9);
                        status := upper(substr(sBuffer,10,1));
                        contract := substr(sBuffer,10,7);
                        update vertraege vr
                        set vr.phone = phone
                        where vr.vertrags_nr = contract;
                        commit;
             exception
                when no_data_found then
                    insert into vertaraege (phone, vertrags_nr)
              values (phone, contract);
              commit;
                when others then
                    raise;
            end;
        end loop;
    ELSE
        raise_application_error(-20001,'can not open file' || sfile || '. or file not exist');
    END IF;
    COMMIT;
EXCEPTION
    WHEN UTL_FILE.INVALID_PATH THEN
        rollback;
        raise_application_error(-20002, 'can not open path:' || sPath);
END; -- Procedure

Best Regards / Vriendelijke Groeten / Salutations Distinguées / Freundliche Grüße !!!
Kasem NEFNIFI
AtosOrigin Belgium N.V.
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