Oracle: Quick way to list all database links

The answer you are probably looking for is

select * from user_objects where object_type = 'FUNCTION';

However this won't return a list of packaged functions. I'm not aware of anyway of returning these other than by querying user_objects for objects of type 'PACKAGE' and then describing each in turn. Someone with a developer hat on might be able to answer the packaged function part of the question.

Rather than doing this, I'd advise on getting the character set info from the nls_database_parameters view & then using DBCA to create a new database, along with dbms_metadata.get_ddl to handle tablespace creation. - Much easier and less prone to error. The character set and national character set are really the only things that are a pain to change when a database has already been created & DBCA lets you chose them in the UI. I imagine you're needing to package some scripts up to automate creation or something?

Anyway, if you really must proceed, you can't do exactly what you're asking out of the box, but you can dump the Control File which will give you most of the information you need to construct a CREATE DATABASE statement, including most pfile parameters (a pfile is required to start a new instance before issuing a CREATE DATABASE statement), redo logs & character set etc.

For example:

SQL> alter database backup controlfile to trace as '/tmp/db.sql';

Database altered.

SQL> !cat /tmp/db.sql
-- The following are current System-scope REDO Log Archival related
-- parameters and can be included in the database initialization file.
--
-- LOG_ARCHIVE_DEST=''
-- LOG_ARCHIVE_DUPLEX_DEST=''
--
-- LOG_ARCHIVE_FORMAT=%t_%s_%r.dbf
--
-- DB_UNIQUE_NAME="PHIL112"
--
-- LOG_ARCHIVE_CONFIG='SEND, RECEIVE, NODG_CONFIG'
-- LOG_ARCHIVE_MAX_PROCESSES=4
-- STANDBY_FILE_MANAGEMENT=MANUAL
-- STANDBY_ARCHIVE_DEST=?/dbs/arch
-- FAL_CLIENT=''
-- FAL_SERVER=''
--
-- LOG_ARCHIVE_DEST_1='LOCATION=USE_DB_RECOVERY_FILE_DEST'
-- LOG_ARCHIVE_DEST_1='MANDATORY NOREOPEN NODELAY'
-- LOG_ARCHIVE_DEST_1='ARCH NOAFFIRM EXPEDITE NOVERIFY SYNC'
-- LOG_ARCHIVE_DEST_1='NOREGISTER NOALTERNATE NODEPENDENCY'
-- LOG_ARCHIVE_DEST_1='NOMAX_FAILURE NOQUOTA_SIZE NOQUOTA_USED NODB_UNIQUE_NAME'
-- LOG_ARCHIVE_DEST_1='VALID_FOR=(PRIMARY_ROLE,ONLINE_LOGFILES)'
-- LOG_ARCHIVE_DEST_STATE_1=ENABLE

--
-- Below are two sets of SQL statements, each of which creates a new
-- control file and uses it to open the database. The first set opens
-- the database with the NORESETLOGS option and should be used only if
-- the current versions of all online logs are available. The second
-- set opens the database with the RESETLOGS option and should be used
-- if online logs are unavailable.
-- The appropriate set of statements can be copied from the trace into
-- a script file, edited as necessary, and executed when there is a
-- need to re-create the control file.
--
--     Set #1. NORESETLOGS case
--
-- The following commands will create a new control file and use it
-- to open the database.
-- Data used by Recovery Manager will be lost.
-- Additional logs may be required for media recovery of offline
-- Use this only if the current versions of all online logs are
-- available.

-- After mounting the created controlfile, the following SQL
-- statement will place the database in the appropriate
-- protection mode:
--  ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PERFORMANCE

STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "PHIL112" NORESETLOGS  ARCHIVELOG
    MAXLOGFILES 16
    MAXLOGMEMBERS 3
    MAXDATAFILES 100
    MAXINSTANCES 8
    MAXLOGHISTORY 292
LOGFILE
  GROUP 1 '/u01/app/oracle/oradata/PHIL112/redo01.log'  SIZE 50M BLOCKSIZE 512,
  GROUP 2 '/u01/app/oracle/oradata/PHIL112/redo02.log'  SIZE 50M BLOCKSIZE 512,
  GROUP 3 '/u01/app/oracle/oradata/PHIL112/redo03.log'  SIZE 50M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
  '/u01/app/oracle/oradata/PHIL112/system01.dbf',
  '/u01/app/oracle/oradata/PHIL112/sysaux01.dbf',
  '/u01/app/oracle/oradata/PHIL112/undotbs01.dbf',
  '/u01/app/oracle/oradata/PHIL112/users01.dbf'
CHARACTER SET WE8MSWIN1252
;

-- Commands to re-create incarnation table
-- Below log names MUST be changed to existing filenames on
-- disk. Any one log file from each branch can be used to
-- re-create incarnation records.
-- ALTER DATABASE REGISTER LOGFILE '/u01/app/oracle/fast_recovery_area/PHIL112/archivelog/2013_01_10/o1_mf_1_1_%u_.arc';
-- ALTER DATABASE REGISTER LOGFILE '/u01/app/oracle/fast_recovery_area/PHIL112/archivelog/2013_01_10/o1_mf_1_1_%u_.arc';
-- Recovery is required if any of the datafiles are restored backups,
-- or if the last shutdown was not normal or immediate.
RECOVER DATABASE

-- All logs need archiving and a log switch is needed.
ALTER SYSTEM ARCHIVE LOG ALL;

-- Database can now be opened normally.
ALTER DATABASE OPEN;

-- Commands to add tempfiles to temporary tablespaces.
-- Online tempfiles have complete space information.
-- Other tempfiles may require adjustment.
ALTER TABLESPACE TEMP ADD TEMPFILE '/u01/app/oracle/oradata/PHIL112/temp01.dbf'
     SIZE 937426944  REUSE AUTOEXTEND ON NEXT 655360  MAXSIZE 32767M;
-- End of tempfile additions.
--
--     Set #2. RESETLOGS case
--
-- The following commands will create a new control file and use it
-- to open the database.
-- Data used by Recovery Manager will be lost.
-- The contents of online logs will be lost and all backups will
-- be invalidated. Use this only if online logs are damaged.

-- After mounting the created controlfile, the following SQL
-- statement will place the database in the appropriate
-- protection mode:
--  ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PERFORMANCE

STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "PHIL112" RESETLOGS  ARCHIVELOG
    MAXLOGFILES 16
    MAXLOGMEMBERS 3
    MAXDATAFILES 100
    MAXINSTANCES 8
    MAXLOGHISTORY 292
LOGFILE
  GROUP 1 '/u01/app/oracle/oradata/PHIL112/redo01.log'  SIZE 50M BLOCKSIZE 512,
  GROUP 2 '/u01/app/oracle/oradata/PHIL112/redo02.log'  SIZE 50M BLOCKSIZE 512,
  GROUP 3 '/u01/app/oracle/oradata/PHIL112/redo03.log'  SIZE 50M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
  '/u01/app/oracle/oradata/PHIL112/system01.dbf',
  '/u01/app/oracle/oradata/PHIL112/sysaux01.dbf',
  '/u01/app/oracle/oradata/PHIL112/undotbs01.dbf',
  '/u01/app/oracle/oradata/PHIL112/users01.dbf'
CHARACTER SET WE8MSWIN1252
;

-- Commands to re-create incarnation table
-- Below log names MUST be changed to existing filenames on
-- disk. Any one log file from each branch can be used to
-- re-create incarnation records.
-- ALTER DATABASE REGISTER LOGFILE '/u01/app/oracle/fast_recovery_area/PHIL112/archivelog/2013_01_10/o1_mf_1_1_%u_.arc';
-- ALTER DATABASE REGISTER LOGFILE '/u01/app/oracle/fast_recovery_area/PHIL112/archivelog/2013_01_10/o1_mf_1_1_%u_.arc';
-- Recovery is required if any of the datafiles are restored backups,
-- or if the last shutdown was not normal or immediate.
RECOVER DATABASE USING BACKUP CONTROLFILE

-- Database can now be opened zeroing the online logs.
ALTER DATABASE OPEN RESETLOGS;

-- Commands to add tempfiles to temporary tablespaces.
-- Online tempfiles have complete space information.
-- Other tempfiles may require adjustment.
ALTER TABLESPACE TEMP ADD TEMPFILE '/u01/app/oracle/oradata/PHIL112/temp01.dbf'
     SIZE 937426944  REUSE AUTOEXTEND ON NEXT 655360  MAXSIZE 32767M;
-- End of tempfile additions.
--

SQL>

Then you can extract the tablespace creation DDL with:

select dbms_metadata.get_ddl('TABLESPACE', tablespace_name) as ts_ddl
from dba_tablespaces;

If you want me to expand further on all of the steps required to manually create a database, just ask (if you don't already know).