.TH erl_prim_loader 3erl "erts 8.2.1" "Ericsson AB" "Erlang Module Definition"
.SH NAME
erl_prim_loader \- Low-level Erlang loader.
.SH DESCRIPTION
.LP
This module 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\&.
.LP
Command-line flag \fI-loader Loader\fR\& can be used to choose the method used by \fIerl_prim_loader\fR\&\&. Two \fILoader\fR\& methods are supported by the Erlang runtime system: \fIefile\fR\& and \fIinet\fR\&\&.
.SH EXPORTS
.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
Fetches a file using the low-level loader\&. \fIFilename\fR\& is either an absolute filename or only 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\&. \fIFullName\fR\& is the complete name of the fetched file\&. \fIBin\fR\& is the contents of the file as a binary\&.
.LP
\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\&\&. For information about archive files, see \fB\fIcode(3erl)\fR\&\fR\&\&.
.RE

.LP
.nf

.B
get_path() -> {ok, Path}
.br
.fi
.br
.RS
.LP
Types:

.RS 3
Path = [Dir :: string()]
.br
.RE
.RE
.RS
.LP
Gets the path set in the loader\&. The path is set by the \fB\fIinit(3erl)\fR\&\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 \fIerror\fR\&\&. \fIFilenames\fR\& is a list of the names of all the files in the directory\&. The names are not sorted\&.
.LP
\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\&\&. For information about archive files, see \fB\fIcode(3erl)\fR\&\fR\&\&.
.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
For more information about the record \fIfile_info\fR\&, see \fB\fIfile(3erl)\fR\&\fR\&\&.
.LP
\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\&\&. For information about archive files, see \fB\fIcode(3erl)\fR\&\fR\&\&.
.RE

.LP
.nf

.B
read_link_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
Works like \fB\fIread_file_info/1\fR\&\fR\& except that if \fIFilename\fR\& is a symbolic link, information about the link is returned in the \fIfile_info\fR\& record and the \fItype\fR\& field of the record is set to \fIsymlink\fR\&\&.
.LP
If \fIFilename\fR\& is not a symbolic link, this function returns exactly the same result as \fIread_file_info/1\fR\&\&. On platforms that do not support symbolic links, this function is always equivalent to \fIread_file_info/1\fR\&\&.
.RE

.LP
.nf

.B
set_path(Path) -> ok
.br
.fi
.br
.RS
.LP
Types:

.RS 3
Path = [Dir :: string()]
.br
.RE
.RE
.RS
.LP
Sets the path of the loader if \fB\fIinit(3erl)\fR\&\fR\& interprets a \fIpath\fR\& command in the start script\&.
.RE

.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)\&.
.RS 2
.LP
If flag \fI-loader\fR\& 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 flag \fI-loader inet\fR\& is present\&. On each host, there must be on Erlang node with the \fB\fIerl_boot_server(3erl)\fR\&\fR\&, which handles the load requests\&. \fIHosts\fR\& is a list of IP addresses (hostnames are not acceptable)\&.
.TP 2
.B
\fI-setcookie Cookie\fR\&:
Specifies the cookie of the Erlang runtime system\&. This flag is mandatory if flag \fI-loader inet\fR\& is present\&.
.RE
.SH "SEE ALSO"

.LP
\fB\fIinit(3erl)\fR\&\fR\&, \fB\fIerl_boot_server(3erl)\fR\&\fR\&