m4_comment([$Id: error.so,v 10.20 2003/10/18 19:16:00 bostic Exp $])

m4_ref_title(Environment, Error support,, env/open, env/db_config)

m4_p([dnl
m4_db offers programmatic support for displaying error return values.
The m4_ref(dbenv_strerror) function returns a pointer to the error
message corresponding to any m4_db error return.  This is similar to the
ANSI C strerror interface, but can handle both system error returns and
m4_db-specific return values.])

m4_p([dnl
For example:])

include(ref/env/error1.cs)

m4_p([dnl
There are also two additional error methods: m4_ref(dbenv_err) and
m4_ref(dbenv_errx).  These methods work like the ANSI C printf function,
taking a printf-style format string and argument list, and writing a
message constructed from the format string and arguments.])

m4_p([dnl
The m4_ref(dbenv_err) function appends the standard error string to the
constructed message; the m4_ref(dbenv_errx) function does not.])

m4_p([dnl
Error messages can be configured always to include a prefix (for
example, the program name) using the m4_refT(dbenv_set_errpfx).])

m4_p([dnl
These functions provide simpler ways of displaying m4_db error messages:])

include(ref/env/error2.cs)

m4_p([dnl
For example, if the program was called "my_app", and it tried to open
an environment home directory in "/tmp/home" and the open call returned
a permission error, the error messages shown would look like this:])

m4_indent([dnl
my_app: open: /tmp/home: Permission denied.
my_app: contact your system administrator: session ID was 2])

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