diff options
author | Dr. Stephen Henson <steve@openssl.org> | 2000-01-21 02:17:04 +0000 |
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committer | Dr. Stephen Henson <steve@openssl.org> | 2000-01-21 02:17:04 +0000 |
commit | dd46d58f65bd3a342bbcd8586680942be643fc7d (patch) | |
tree | f573df02bef40f2fcc2f81b0aa89f37b0f40819f /doc/apps/config.pod | |
parent | e7f97e2d22e386df60c8da63277727a931bf22b7 (diff) |
Change the 'man' directory to 'apps'. Yes I wish cvs
could rename too :-(
Diffstat (limited to 'doc/apps/config.pod')
-rw-r--r-- | doc/apps/config.pod | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/doc/apps/config.pod b/doc/apps/config.pod new file mode 100644 index 0000000000..a5974d945a --- /dev/null +++ b/doc/apps/config.pod @@ -0,0 +1,138 @@ + +=pod + +=head1 NAME + +config - OpenSSL CONF library configuration files + +=head1 DESCRIPTION + +The OpenSSL CONF library can be used to read configuration files. +It is used for the OpenSSL master configuration file B<openssl.cnf> +and in a few other places like B<SPKAC> files and certificate extension +files for the B<x509> utility. + +A configuration file is divided into a number of sections. Each section +starts with a line B<[ 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 B<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 B<ENV>. + +Comments can be included by preceding them with the B<#> character + +Each section in a configuration file consists of a number of name and +value pairs of the form B<name=value> + +The B<name> string can contain any alphanumeric characters as well as +a few punctuation symbols such as B<.> B<,> B<;> and B<_>. + +The B<value> string consists of the string following the B<=> 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 B<$var> or B<${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 B<$section::name> +or B<${section::name}>. By using the form B<$ENV::name> environment +variables can be substituted. It is also possible to assign values to +environment variables by using the name B<ENV::name>, this will work +if the program looks up environment variables using the B<CONF> library +instead of calling B<getenv()> directly. + +It is possible to escape certain characters by using any kind of quote +or the B<\> character. By making the last character of a line a B<\> +a B<value> string can be spread across multiple lines. In addition +the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognised. + +=head1 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 B<HOME> which may not be defined on non Unix systems. + +This can be worked around by including a B<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 B<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 B<.> e.g. + + 1.OU="My first OU" + 2.OU="My Second OU" + +=head1 EXAMPLES + +Here is a sample configuration file using some of the features +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 = $section_one::message + +This next example shows how to expand environment variables safely. + +Suppose you want a variable called B<tmpfile> to refer to a +temporary filename. The directory it is placed in can determined by +the the B<TEMP> or B<TMP> environment variables but they may not be +set to any value at all. If you just include the environment variable +names and the variable doesn't exist then this will cause an error when +an attempt is made to load the configuration file. By making use of the +default section both values can be looked up with B<TEMP> taking +priority and B</tmp> used if neither is defined: + + TMP=/tmp + # The above value is used if TMP isn't in the environment + TEMP=$ENV::TMP + # The above value is used if TEMP isn't in the environment + tmpfile=${ENV::TEMP}/tmp.filename + +=head1 BUGS + +Currently there is no way to include characters using the octal B<\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 B<\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 referenced are defined earlier in the +file. + +=head1 SEE ALSO + +x509(1), req(1), ca(1) + +=cut |