There is a bit of practical split about where WP can write files and if Filesystem API is invoked. It might be easier to see this divide not as technical, but as administrative. There is user space. Users must be able to do things like create attachments and must not need to have admin access … Read more
WP_Filesystem abstraction is primarily meant for performing plugin/theme/core updates, especially in environments with restricted writes. As such it doesn’t really implement full range of possible file operations, as you noted there is no ability to write to the end of file in declared API. More so some possible implementations (depending on file system) might not … Read more
I had to dig pretty deep for this too, and eventually figured out some way to do this. in my solution I used the following: WP_Filesystem(); global $wp_filesystem; $wp_filesystem->exists( ‘/path/to/file’ ); //use any other functions available in the Filesystem API: @see https://developer.wordpress.org/reference/classes/wp_filesystem_direct/
require_once(ABSPATH .’/wp-admin/includes/file.php’); global $wp_filesystem; if ( ! $filesystem ) { WP_Filesystem(); if ( ! $wp_filesystem ) nuke_the_world_because_wpfs_cannot_be_initialized_in_case_of_missing_arguments(‘!’); } $result = unzip_file( $zip, $dest ); if ( is_wp_error( $result ) ) nuke_the_world(); Maybe some error handling make it easier.
To answer your question, you have specified the paths incorrectly: plugin_dir_path( __FILE__ ) already has a trailing slash at the end (having two trailing slashes should not be a problem, but safer is to have one) and get_stylesheet_directory() comes with no trailing slash at the end, so you have to add one before adding the … Read more
Initialize the WP filesystem and no more using file_put_contents function. Try this: […] global $wp_filesystem; // Initialize the WP filesystem, no more using ‘file-put-contents’ function if (empty($wp_filesystem)) { require_once (ABSPATH . ‘/wp-admin/includes/file.php’); WP_Filesystem(); } if(!$wp_filesystem->put_contents( $path, $css, 0644) ) { return __(‘Failed to create css file’); }