config(5)                    OpenSSL                    config(5)



NAME
       config - OpenSSL CONF library configuration files

DESCRIPTION
       The OpenSSL CONF library can be used to read configuration
       files.  It is used for the OpenSSL master configuration
       file openssl.cnf and in a few other places like SPKAC
       files and certificate extension files for the x509 util-
       ity.

       A configuration file is divided into a number of sections.
       Each section starts with a line [ section_name ] and ends
       when a new section is started or end of file is reached. A
       section name can consist of alphanumeric characters and
       underscores.

       The first section of a configuration file is special and
       is referred to as the default section this is usually
       unnamed and is from the start of file until the first
       named section. When a name is being looked up it is first
       looked up in a named section (if any) and then the default
       section.

       The environment is mapped onto a section called ENV.

       Comments can be included by preceding them with the #
       character

       Each section in a configuration file consists of a number
       of name and value pairs of the form name=value

       The name string can contain any alphanumeric characters as
       well as a few punctuation symbols such as . , ; and _.

       The value string consists of the string following the =
       character until end of line with any leading and trailing
       white space removed.

       The value string undergoes variable expansion. This can be
       done by including the form $var or ${var}: this will sub-
       stitute the value of the named variable in the current
       section. It is also possible to substitute a value from
       another section using the syntax $section::name or ${sec-
       tion::name}. By using the form $ENV::name environment
       variables can be substituted. It is also possible to
       assign values to environment variables by using the name
       ENV::name, this will work if the program looks up environ-
       ment variables using the CONF library instead of calling
       getenv() directly.

       It is possible to escape certain characters by using any
       kind of quote or the \ character. By making the last char-
       acter of a line a \ a value string can be spread across
       multiple lines. In addition the sequences \n, \r, \b and
       \t are recognized.

NOTES
       If a configuration file attempts to expand a variable that
       doesn't exist then an error is flagged and the file will
       not load. This can happen if an attempt is made to expand
       an environment variable that doesn't exist. For example
       the default OpenSSL master configuration file used the
       value of HOME which may not be defined on non Unix sys-
       tems.

       This can be worked around by including a default section
       to provide a default value: then if the environment lookup
       fails the default value will be used instead. For this to
       work properly the default value must be defined earlier in
       the configuration file than the expansion. See the EXAM-
       PLES section for an example of how to do this.

       If the same variable exists in the same section then all
       but the last value will be silently ignored. In certain
       circumstances such as with DNs the same field may occur
       multiple times. This is usually worked around by ignoring
       any characters before an initial . e.g.

        1.OU="My first OU"
        2.OU="My Second OU"


EXAMPLES
       Here is a sample configuration file using some of the fea-
       tures mentioned above.

        # This is the default section.

        HOME=/temp
        RANDFILE= ${ENV::HOME}/.rnd
        configdir=$ENV::HOME/config

        [ section_one ]

        # We are now in section one.

        # Quotes permit leading and trailing whitespace
        any = " any variable name "

        other = A string that can \
        cover several lines \
        by including \\ characters

        message = Hello World\n

        [ section_two ]

        greeting = $section_one::message

       This next example shows how to expand environment vari-
       ables safely.

       Suppose you want a variable called tmpfile to refer to a
       temporary filename. The directory it is placed in can
       determined by the the TEMP or TMP environment variables
       but they may not be set to any value at all. If you just
       include the environment variable names and the variable
       doesn't exist then this will cause an error when an
       attempt is made to load the configuration file. By making
       use of the default section both values can be looked up
       with TEMP taking priority and /tmp used if neither is
       defined:

        TMP=/tmp
        # The above value is used if TMP isn't in the environment
        TEMP=$ENV::TMP
        # The above value is used if TEMP isn't in the environment
        tmpfile=${ENV::TEMP}/tmp.filename


BUGS
       Currently there is no way to include characters using the
       octal \nnn form. Strings are all null terminated so nulls
       cannot form part of the value.

       The escaping isn't quite right: if you want to use
       sequences like \n you can't use any quote escaping on the
       same line.

       Files are loaded in a single pass. This means that an
       variable expansion will only work if the variables refer-
       enced are defined earlier in the file.

SEE ALSO
       x509(1), req(1), ca(1)



2000-05-24                    0.9.6e                    config(5)