/wp-admin/includes/misc.php includes the function insert_with_markers() :
/**
* Inserts an array of strings into a file (.htaccess ), placing it between
* BEGIN and END markers.
*
* Replaces existing marked info. Retains surrounding
* data. Creates file if none exists.
*
* @since 1.5.0
*
* @param string $filename Filename to alter.
* @param string $marker The marker to alter.
* @param array|string $insertion The new content to insert.
* @return bool True on write success, false on failure.
*/
function insert_with_markers( $filename, $marker, $insertion ) {
insert_with_markers() checks whether the file exists & is writable, creating it if necessary. It inserts your data into the file between # BEGIN and # END markers, replacing any lines that already exist between those markers. You can pass it an array of lines or a string with line breaks. Make sure your marker name is unique to avoid clashing with WP core or other plugins.
In the same core file, save_mod_rewrite_rules() shows how WP sets up $filename, $marker & $insertion for the default permalink rules, so stealing heavily from that function:
if ( is_multisite() ) {
// I'm not going to go here
} else {
// Ensure get_home_path() is declared.
require_once( ABSPATH . 'wp-admin/includes/file.php' );
$home_path = get_home_path();
$htaccess_file = $home_path . '.htaccess';
$lines = array(
'# These are',
'# the lines',
'# I want to add',
);
if ( insert_with_markers( $htaccess_file, 'wpse_331608', $lines ) ) {
// Celebrate your success
} else {
// Deal with your failure
}
}
If your rules are for rewrites, then WP also has a helper function to check you are using Apache with mod_rewrite enabled:
if ( got_mod_rewrite() ) {
if ( insert_with_markers( $htaccess_file, 'wpse_331608', $lines ) ) {
// Celebrate your success
} else {
// Deal with your failure
}
}