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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
  utility.

  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 substitute 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
  ${section::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
  environment 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 character 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 systems.

  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
  EXAMPLES 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 . Two examples follow:

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

RESTRICTIONS
  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 such as \n you
  cannot use any quote escaping on the same line.

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

EXAMPLES
  This sample configuration file uses some of the features mentioned:

	# 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

  The following example shows how to expand environment variables 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 include the environment variable names and the variable does not 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

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

Index for Section 5

Alphabetical listing for C

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