EVOLUTION-MANAGER

Edit File: erl_prim_loader.3

.TH erl_prim_loader 3 "erts 5.10.4" "Ericsson AB" "Erlang Module Definition" .SH NAME erl_prim_loader \- Low Level Erlang Loader .SH DESCRIPTION .LP \fIerl_prim_loader\fR\& is used to load all Erlang modules into the system\&. The start script is also fetched with this low level loader\&. .LP \fIerl_prim_loader\fR\& knows about the environment and how to fetch modules\&. The loader could, for example, fetch files using the file system (with absolute file names as input), or a database (where the binary format of a module is stored)\&. .LP The \fI-loader Loader\fR\& command line flag can be used to choose the method used by the \fIerl_prim_loader\fR\&\&. Two \fILoader\fR\& methods are supported by the Erlang runtime system: \fIefile\fR\& and \fIinet\fR\&\&. If another loader is required, then it has to be implemented by the user\&. The \fILoader\fR\& provided by the user must fulfill the protocol defined below, and it is started with the \fIerl_prim_loader\fR\& by evaluating \fIopen_port({spawn,Loader},[binary])\fR\&\&. .LP .RS -4 .B Warning: .RE The support for loading of code from archive files is experimental\&. The sole purpose of releasing it before it is ready is to obtain early feedback\&. The file format, semantics, interfaces etc\&. may be changed in a future release\&. The functions \fIlist_dir/1\fR\& and \fIread_file_info/1\fR\& as well as the flag \fI-loader_debug\fR\& are also experimental .SH DATA TYPES .nf \fBhost()\fR\& = atom() .br .fi .SH EXPORTS .LP .nf .B start(Id, Loader, Hosts) -> {ok, Pid} | {error, What} .br .fi .br .RS .LP Types: .RS 3 Id = term() .br Loader = atom() | string() .br Hosts = Host | [Host] .br Host = \fBhost()\fR\& .br Pid = pid() .br What = term() .br .RE .RE .RS .LP Starts the Erlang low level loader\&. This function is called by the \fIinit\fR\& process (and module)\&. The \fIinit\fR\& process reads the command line flags \fI-id Id\fR\&, \fI-loader Loader\fR\&, and \fI-hosts Hosts\fR\&\&. These are the arguments supplied to the \fIstart/3\fR\& function\&. .LP If \fI-loader\fR\& is not given, the default loader is \fIefile\fR\& which tells the system to read from the file system\&. .LP If \fI-loader\fR\& is \fIinet\fR\&, the \fI-id Id\fR\&, \fI-hosts Hosts\fR\&, and \fI-setcookie Cookie\fR\& flags must also be supplied\&. \fIHosts\fR\& identifies hosts which this node can contact in order to load modules\&. One Erlang runtime system with a \fIerl_boot_server\fR\& process must be started on each of hosts given in \fIHosts\fR\& in order to answer the requests\&. See \fBerl_boot_server(3)\fR\&\&. .LP If \fI-loader\fR\& is something else, the given port program is started\&. The port program is supposed to follow the protocol specified below\&. .RE .LP .nf .B get_file(Filename) -> {ok, Bin, FullName} | error .br .fi .br .RS .LP Types: .RS 3 Filename = atom() | string() .br Bin = binary() .br FullName = string() .br .RE .RE .RS .LP This function fetches a file using the low level loader\&. \fIFilename\fR\& is either an absolute file name or just the name of the file, for example \fI"lists\&.beam"\fR\&\&. If an internal path is set to the loader, this path is used to find the file\&. If a user supplied loader is used, the path can be stripped off if it is obsolete, and the loader does not use a path\&. \fIFullName\fR\& is the complete name of the fetched file\&. \fIBin\fR\& is the contents of the file as a binary\&. .LP The \fIFilename\fR\& can also be a file in an archive\&. For example \fI$OTPROOT/lib/\fR\&\fImnesia-4\&.4\&.7\&.ez/mnesia-4\&.4\&.7/ebin/\fR\&\fImnesia\&.beam\fR\&\&. See \fBcode(3)\fR\& about archive files\&. .RE .LP .nf .B get_path() -> {ok, Path} .br .fi .br .RS .LP Types: .RS 3 Path = [Dir :: string()] .br .RE .RE .RS .LP This function gets the path set in the loader\&. The path is set by the \fIinit\fR\& process according to information found in the start script\&. .RE .LP .nf .B list_dir(Dir) -> {ok, Filenames} | error .br .fi .br .RS .LP Types: .RS 3 Dir = string() .br Filenames = [Filename :: string()] .br .RE .RE .RS .LP Lists all the files in a directory\&. Returns \fI{ok, Filenames}\fR\& if successful\&. Otherwise, it returns \fIerror\fR\&\&. \fIFilenames\fR\& is a list of the names of all the files in the directory\&. The names are not sorted\&. .LP The \fIDir\fR\& can also be a directory in an archive\&. For example \fI$OTPROOT/lib/\fR\&\fImnesia-4\&.4\&.7\&.ez/mnesia-4\&.4\&.7/ebin\fR\&\&. See \fBcode(3)\fR\& about archive files\&. .RE .LP .nf .B read_file_info(Filename) -> {ok, FileInfo} | error .br .fi .br .RS .LP Types: .RS 3 Filename = string() .br FileInfo = \fBfile:file_info()\fR\& .br .RE .RE .RS .LP Retrieves information about a file\&. Returns \fI{ok, FileInfo}\fR\& if successful, otherwise \fIerror\fR\&\&. \fIFileInfo\fR\& is a record \fIfile_info\fR\&, defined in the Kernel include file \fIfile\&.hrl\fR\&\&. Include the following directive in the module from which the function is called: .LP .nf -include_lib("kernel/include/file.hrl"). .fi .LP See \fBfile(3)\fR\& for more info about the record \fIfile_info\fR\&\&. .LP The \fIFilename\fR\& can also be a file in an archive\&. For example \fI$OTPROOT/lib/\fR\&\fImnesia-4\&.4\&.7\&.ez/mnesia-4\&.4\&.7/ebin/\fR\&\fImnesia\fR\&\&. See \fBcode(3)\fR\& about archive files\&. .RE .LP .nf .B set_path(Path) -> ok .br .fi .br .RS .LP Types: .RS 3 Path = [Dir :: string()] .br .RE .RE .RS .LP This function sets the path of the loader if \fIinit\fR\& interprets a \fIpath\fR\& command in the start script\&. .RE .SH "PROTOCOL" .LP The following protocol must be followed if a user provided loader port program is used\&. The \fILoader\fR\& port program is started with the command \fIopen_port({spawn,Loader},[binary])\fR\&\&. The protocol is as follows: .LP .nf Function Send Receive ------------------------------------------------------------- get_file [102 | FileName] [121 | BinaryFile] (on success) [122] (failure) stop eof terminate .fi .SH "COMMAND LINE FLAGS" .LP The \fIerl_prim_loader\fR\& module interprets the following command line flags: .RS 2 .TP 2 .B \fI-loader Loader\fR\&: Specifies the name of the loader used by \fIerl_prim_loader\fR\&\&. \fILoader\fR\& can be \fIefile\fR\& (use the local file system), or \fIinet\fR\& (load using the \fIboot_server\fR\& on another Erlang node)\&. If \fILoader\fR\& is user defined, the defined \fILoader\fR\& port program is started\&. .RS 2 .LP If the \fI-loader\fR\& flag is omitted, it defaults to \fIefile\fR\&\&. .RE .TP 2 .B \fI-loader_debug\fR\&: Makes the \fIefile\fR\& loader write some debug information, such as the reason for failures, while it handles files\&. .TP 2 .B \fI-hosts Hosts\fR\&: Specifies which other Erlang nodes the \fIinet\fR\& loader can use\&. This flag is mandatory if the \fI-loader inet\fR\& flag is present\&. On each host, there must be on Erlang node with the \fIerl_boot_server\fR\& which handles the load requests\&. \fIHosts\fR\& is a list of IP addresses (hostnames are not acceptable)\&. .TP 2 .B \fI-id Id\fR\&: Specifies the identity of the Erlang runtime system\&. If the system runs as a distributed node, \fIId\fR\& must be identical to the name supplied with the \fI-sname\fR\& or \fI-name\fR\& distribution flags\&. .TP 2 .B \fI-setcookie Cookie\fR\&: Specifies the cookie of the Erlang runtime system\&. This flag is mandatory if the \fI-loader inet\fR\& flag is present\&. .RE .SH "SEE ALSO" .LP \fBinit(3)\fR\&, \fBerl_boot_server(3)\fR\&