//usage: IF_FEATURE_DU_DEFAULT_BLOCKSIZE_1K("1024")
//usage: IF_NOT_FEATURE_DU_DEFAULT_BLOCKSIZE_1K("512")
//usage: " bytes.\n"
-//usage: "\nOptions:"
//usage: "\n -a Show file sizes too"
//usage: "\n -L Follow all symlinks"
//usage: "\n -H Follow symlinks on command line"