getconf -a [-v specification] [pathname]

If the -a option is specified, the getconf utility shall write to the standard output the names and values of all valid configuration variables; that is, every system_var operand and every path_var operand that the utility accepts, together with the values of the variables specified by those operands. For path_var operands the value written shall be the value of the variable for the path specified by the pathname operand, if present; if no pathname is provided, it is implementation-defined whether the value is for the current working directory (.) or the root directory (/).

The following option shall be supported:

The following options shall be supported:

-a

Write the names and values of all valid configuration variables.

If the -a option is specified, the name of each valid configuration variable and information about the variable shall be written in the following format:

"%s: %s\n", <name>, <info_string>

where <info_string> is the information string that would be written (without the terminating <newline>) for the variable if specified as an operand, as described below.

The remainder of this section describes the behavior if the -a option is not specified.

The specified variable is valid and information about its current state was written successfully.

The -a option was specified and the names of all valid configuration variables were written successfully together with information about each variable's current state, or the -a option was not specified, the specified variable is valid, and information about its current state was written successfully.

None.

Since the value of a configuration variable obtained from confstr() may include <newline> characters, the output when the -a option is specified cannot be assumed to contain one name and value per line. Applications can use the presence of a <colon> at the end of the variable name as a means to distinguish names from parts of values that follow a <newline>; however, it is possible (although unlikely) for a multi-line value to match this and it is recommended that applications needing to extract a list of valid variable names should confirm their validity by checking whether getconf accepts them as either a system_var or path_var operand.

Historically the GNU implementation of getconf -a did not output a <colon> after each variable name, whereas other implementations did. The standard developers decided to require the <colon> in order to help applications and users distinguish variable names from parts of values that follow a <newline>. In some implementations the use of -v with -a was undocumented but supported; in others it was not supported, but it was felt to be a useful feature that would be simple to provide.