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3.4 Command-line options

While you are free to provide any command-line option to enable the styling of the output, it is good if different GNU programs use the same command-line options for this purpose. These options are described in the sections The --color option and The --style option. To achieve this, use the following API (declared in <textstyle.h>):

Variable: bool color_test_mode

True if a --color option with value test has been seen.

Variable: enum color_option color_mode

Stores the value of the --color option.

Variable: const char * style_file_name

Stores the value of the --style option.

Note: These variables, like any variables exported from shared libraries, can only be used in executable code. You cannot portably use their address in initializers of global or static variables. This is a restriction that is imposed by the Windows, Cygwin, and Android platforms.

Function: bool handle_color_option (const char *option)

You invoke this function when, during argument parsing, you have encountered a --color or --color=... option. The return value is an error indicator: true means an invalid option.

Function: void handle_style_option (const char *option)

You invoke this function when, during argument parsing, you have encountered a --style or --style=... option.

Function: void print_color_test (void)

Prints a color test page. You invoke this function after argument parsing, when the color_test_mode variable is true.

Function: void style_file_prepare (const char *style_file_envvar, const char *stylesdir_envvar, const char *stylesdir_after_install, const char *default_style_file)

Assigns a default value to style_file_name if necessary. You invoke this function after argument parsing, when color_test_mode is false.

style_file_envvar is an environment variable that, when set to a non-empty value, specifies the style file to use. This environment variable is meant to be set by the user.

stylesdir_envvar is an environment variable that, when set to a non-empty value, specifies the directory with the style files, or NULL. This is necessary for running the testsuite before ‘make install’.

stylesdir_after_install is the directory with the style files after ‘make install’.

default_style_file is the file name of the default style file, relative to stylesdir.


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