The
db_load
utility reads from the standard input
and loads it into the database
db_file.
The database
db_file
is created if it does not already exist.
The input to
db_load
must be in the output format specified by the
db_dump
or
db_dump185
utilities (see
db_dump(1)
for more information), or as specified for the
-T
option below.
The options are as follows:
-c
Specify configuration options for the DB_INFO structure provided to
db_open(3),
ignoring any value they may have based on the input.
The command-line format is ``name=value''.
Supported keywords are listed below.
-f
Read from the specified
input
file instead of from the standard input.
-h
Specify a home directory for the database.
If a home directory is specified, the database environment is opened
using the DB_INIT_LOCK, DB_INIT_LOG, DB_INIT_MPOOL, DB_INIT_TXN and
DB_USE_ENVIRON flags to
db_appinit(3).
(This means that
db_load
can be used to load data into databases while they are in use by other
processes.)
If the
db_appinit
call fails, or if no home directory is specified, the database is still
updated, but the environment is ignored, e.g., no locking is done.
-n
Do not overwrite existing keys in the database when loading into an
already existing database.
If a key/data pair cannot be loaded into the database for this reason,
a warning message is displayed on the standard error output and the
key/data pair are skipped.
-T
The
-T
option allows non-DB applications to easily load text files into databases.
If the database to be created is of type
btree
or
hash,
the input must be paired lines of text,
where the first line of the pair is the key item,
and the second line of the pair is its corresponding data item.
If the database to be created is of type
recno,
the input must be lines of text,
where each line is a new data item for the database.
A simple escape mechanism, where newline and backslash (``\'') characters
are special, is applied to the text input.
Newline characters are interpreted as record separators.
Backslash characters in the text will be interpreted in one of two ways:
if the backslash character precedes another backslash character, the pair
will be interpreted as a literal backslash.
If the backslash character precedes any other character, the two characters
following the backslash will be interpreted as hexadecimal specification of
a single character, e.g., ``\0a'' is a newline character in the ASCII
character set.
For this reason, any backslash or newline characters that naturally occur
in the text input must be escaped to avoid misinterpretation by
db_load.
If the
-T
option is specified, the underlying access method type must be specified
using the
-t
option.
-t
Specify the underlying access method.
If no
-t
option is specified, the database will be loaded into a database of the
same type as was dumped,
e.g., a hash database will be created if a hash database was dumped.
Btree and hash databases may be converted from one to the other.
Recno databases may not be converted to any other database type
or from any other database type.
The
db_load
utility exits 0 on success, 1 if one or more key/data pairs were not
loaded into the database because the key already existed, and >1 if
an error occurs.
KEYWORDS
The following keywords are supported for the
-c
command-line option.
See
db_open(3)
for further discussion of these keywords and what values should be specified.
The parenthetical listing specifies how the value part of the ``name=value''
pair is interpreted.
Items listed as (boolean) expect value to be ``1'' (set) or ``0'' (unset).
Items listed as (number) convert value to a number.
Items listed as (string) use the characters of value directly.
bt_minkey (number)
The minimum number of keys per page.
db_lorder (number)
The byte order for integers in the stored database metadata.
db_pagesize (number)
The size of pages used for nodes in the tree, in bytes.
duplicates (boolean)
The value of the DB_DUP flag.
h_ffactor (number)
The density within the hash table.
h_nelem (number)
The size of the hash table.
re_len (number)
Specify fixed-length records of the specified length.
re_pad (string)
Specify the fixed-length record pad character.
recnum (boolean)
The value of the DB_RECNUM flag.
renumber (boolean)
The value of the DB_RENUMBER flag.
EXAMPLES
The
db_load
utility can be used to load text files into databases.
For example, the following command loads the standard UNIX
/etc/passwd
file into a database,
with the login name as the key item and the entire password entry as the
data item:
Note that backslash characters naturally occurring in the text are escaped
to avoid interpretation as escape characters by
db_load.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of
db_load:
DB_HOME
If the
-h
option is not specified and the environment variable
DB_HOME
is set, it is used as the path of the database home, as described in
db_appinit(3).
SEE ALSO
The DB library is a family of classes that provides a modular
programming interface to transactions and record-oriented file access.
The library includes support for transactions, locking, logging and file
page caching, as well as various indexed access methods.
Many of the classes (e.g., the file page caching class)
are useful independent of the other DB classes,
although some classes are explicitly based on other classes
(e.g., transactions and logging).