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<title>Berkeley DB: DbEnv::remove</title>
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DbEnv::remove
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<pre>
#include &lt;db_cxx.h&gt;

int
DbEnv::remove(const char *db_home, u_int32_t flags);
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Description: DbEnv::remove
The DbEnv::remove method destroys a Berkeley DB environment if it is not
currently in use. The environment regions, including any backing files,
are removed. Any log or database files and the environment directory are
not removed.
If there are processes that have called <a href="../../db4-devel-4.7.25/api_cxx/env_open.html">DbEnv::open</a> without
calling <a href="../../db4-devel-4.7.25/api_cxx/env_close.html">DbEnv::close</a> (that is, there are processes currently
using the environment), DbEnv::remove will fail without further
action unless the <a href="../../db4-devel-4.7.25/api_cxx/env_remove.html#DB_FORCE">DB_FORCE</a> flag is set, in which case
DbEnv::remove will attempt to remove the environment, regardless
of any processes still using it.
The result of attempting to forcibly destroy the environment when it is
in use is unspecified. Processes using an environment often maintain open
file descriptors for shared regions within it. On UNIX systems, the
environment removal will usually succeed, and processes that have already
joined the region will continue to run in that region without change.
However, processes attempting to join the environment will either fail
or create new regions. On other systems in which the unlink(2) system call will fail if any process has an open file descriptor for
the file (for example Windows/NT), the region removal will fail.
Calling DbEnv::remove should not be necessary for most applications
because the Berkeley DB environment is cleaned up as part of normal database
recovery procedures. However, applications may want to call
DbEnv::remove as part of application shut down to free up system
resources. For example, if the <a href="../../db4-devel-4.7.25/api_cxx/env_open.html#DB_SYSTEM_MEM">DB_SYSTEM_MEM</a> flag was specified
to <a href="../../db4-devel-4.7.25/api_cxx/env_open.html">DbEnv::open</a>, it may be useful to call DbEnv::remove in
order to release system shared memory segments that have been allocated.
Or, on architectures in which mutexes require allocation of underlying
system resources, it may be useful to call DbEnv::remove in order
to release those resources. Alternatively, if recovery is not required
because no database state is maintained across failures, and no system
resources need to be released, it is possible to clean up an environment
by simply removing all the Berkeley DB files in the database environment's
directories.
In multithreaded applications, only a single thread may call
DbEnv::remove.
A <a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> handle that has already been used to open an environment
should not be used to call the DbEnv::remove method; a new
<a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> handle should be created for that purpose.
After DbEnv::remove has been called, regardless of its return,
the Berkeley DB environment handle may not be accessed again.
The DbEnv::remove method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.

Parameters 
 db_home<ul compact><li>The db_home parameter names the database environment to be removed.</ul>
When using a Unicode build on Windows (the default), the db_home
argument will be interpreted as a UTF-8 string, which is equivalent to
ASCII for Latin characters.
 flags<ul compact><li>The flags parameter must be set to 0 or by bitwise inclusively OR'ing together one
or more of the following values:
 
<a name="DB_FORCE">DB_FORCE</a><ul compact><li>If the <a href="../../db4-devel-4.7.25/api_cxx/env_remove.html#DB_FORCE">DB_FORCE</a> flag is set, the environment is removed, regardless
of any processes that may still using it, and no locks are acquired
during this process. (Generally, the <a href="../../db4-devel-4.7.25/api_cxx/env_remove.html#DB_FORCE">DB_FORCE</a> flag is
specified only when applications were unable to shut down cleanly, and there
is a risk that an application may have died holding a Berkeley DB lock.)</ul>
<a name="2"></a>
<a name="DB_USE_ENVIRON">DB_USE_ENVIRON</a><ul compact><li>The Berkeley DB process' environment may be permitted to specify information
to be used when naming files; see <a href="../../db4-devel-4.7.25/ref/env/naming.html">Berkeley DB File Naming</a>. Because permitting users to specify which files
are used can create security problems, environment information will be
used in file naming for all users only if the DB_USE_ENVIRON
flag is set.</ul>
<a name="DB_USE_ENVIRON_ROOT">DB_USE_ENVIRON_ROOT</a><ul compact><li>The Berkeley DB process' environment may be permitted to specify information
to be used when naming files; see <a href="../../db4-devel-4.7.25/ref/env/naming.html">Berkeley DB File Naming</a>. Because permitting users to specify which files
are used can create security problems, if the
DB_USE_ENVIRON_ROOT flag is set, environment information will
be used for file naming only for users with appropriate permissions (for
example, users with a user-ID of 0 on UNIX systems).</ul>
 </ul>
 
 Errors
The DbEnv::remove method
may fail and throw
<a href="../../db4-devel-4.7.25/api_cxx/except_class.html">DbException</a>,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:
 
EBUSY<ul compact><li>The shared memory region was in use and the force flag was not set.</ul>
 
<hr size=1 noshade>
 Class
<a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a>
 See Also
<a href="../../db4-devel-4.7.25/api_cxx/env_list.html">Database Environments and Related Methods</a>
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