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WFDB applications make use of several environment variables, which are
If these variables have not been otherwise defined by the user, their values
are those given by
DEFWFDBANNSORT (defined in ‘wfdblib.h’ at the
time the WFDB library was compiled). Unless you have a non-standard
setup, you may not need to set these variables, but it will be helpful
to read this section to understand how they influence the behavior of
When WFDB applications read database files, they must be able to find them in various locations that may vary from system to system. The WFDB library refers to a character string that consists of an ordered list of locations to be searched for input files. This string is called the database path, or the WFDB path.
On most systems, the environment variable
WFDB, if set, specifies
the value of the WFDB path, and overrides the default value. If you
need to use a non-default WFDB path, you must set the
environment variable appropriately before running any WFDB applications,
so that the WFDB path can be examined by the running program. The WFDB
software package includes easily customizable shell scripts (batch
files) that illustrate how to do this for popular shells and command
interpreters; see setwfdb(1), in the WFDB Applications
Guide. (Under classic Mac OS, for which the concept of environment
variables is foreign, the WFDB path may be set only by using
DEFWFDB.) For further information, see section More About the WFDB Path.
The shell scripts that set
WFDB also set the
environment variable, which is important if you make use of records that
contain signals other than ECGs.
WFDBCAL names a
calibration file located in one of the directories named by
WFDB. (The symbol
DEFWFDBCAL is usually defined in
‘wfdblib.h’ to specify the name of a default calibration file, to
be used by the WFDB library if
WFDBCAL has not been set.) Each
signal type may be represented by an entry in the calibration file.
Entries specify the characteristics of any calibration pulses that may
be present, and customary scales for plotting the signals.
The other environment variables are less frequently used than
WFDBCAL, and in most cases, the compiled-in defaults will be
appropriate (see section Annotation Order, and see section Multi-Frequency Records,
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George B. Moody (email@example.com)