1script(5)                            Files                           script(5)
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NAME

6       script - Boot script
7

DESCRIPTION

9       The  boot script describes how the Erlang runtime system is started. It
10       contains instructions on which code to load and which processes and ap‐
11       plications to start.
12
13       Command  erl  -boot  Name  starts  the  system  with a boot file called
14       Name.boot, which is generated from the  Name.script  file,  using  sys‐
15       tools:script2boot/1.
16
17       The  .script  file  is  generated by systools from a .rel file and from
18       .app files.
19

FILE SYNTAX

21       The boot script is stored in a file with extension  .script.  The  file
22       has the following syntax:
23
24       {script, {Name, Vsn},
25        [
26         {progress, loading},
27         {preLoaded, [Mod1, Mod2, ...]},
28         {path, [Dir1,"$ROOT/Dir",...]}.
29         {primLoad, [Mod1, Mod2, ...]},
30         ...
31         {kernel_load_completed},
32         {progress, loaded},
33         {kernelProcess, Name, {Mod, Func, Args}},
34         ...
35         {apply, {Mod, Func, Args}},
36         ...
37         {progress, started}]}.
38
39         Name = string():
40           Defines the system name.
41
42         Vsn = string():
43           Defines the system version.
44
45         {progress, Term}:
46           Sets   the   "progress"   of   the   initialization   program.  The
47           init:get_status/0  function  returns  the  current  value  of   the
48           progress, which is {InternalStatus,Term}.
49
50         {path, [Dir]}:
51           Dir  is a string. This argument sets the load path of the system to
52           [Dir]. The load path used to load modules is obtained from the ini‐
53           tial  load  path,  which is given in the script file, together with
54           any path flags that were supplied in  the  command-line  arguments.
55           The command-line arguments modify the path as follows:
56
57           * -pa  Dir1  Dir2  ... DirN adds the directories DirN, DirN-1, ...,
58             Dir2, Dir1 to the front of the initial load path.
59
60           * -pz Dir1 Dir2 ... DirN adds the directories Dir1, Dir2, ..., DirN
61             to the end of the initial load path.
62
63           * -path Dir1 Dir2 ... DirN defines a set of directories Dir1, Dir2,
64             ..., DirN, which replace the search  path  given  in  the  script
65             file. Directory names in the path are interpreted as follows:
66
67             * Directory names starting with / are assumed to be absolute path
68               names.
69
70             * Directory names not starting with / are assumed to be  relative
71               the current working directory.
72
73             * The  special $ROOT variable can only be used in the script, not
74               as a command-line argument. The given directory is relative the
75               Erlang installation directory.
76
77         {primLoad, [Mod]}:
78           Loads the modules [Mod] from the directories specified in Path. The
79           script  interpreter  fetches  the  appropriate  module  by  calling
80           erl_prim_loader:get_file(Mod).  A  fatal  error that terminates the
81           system occurs if the module cannot be located.
82
83         {kernel_load_completed}:
84           Indicates that all modules that must be loaded before any processes
85           are  started  are loaded. In interactive mode, all {primLoad,[Mod]}
86           commands interpreted after this command are ignored, and these mod‐
87           ules  are loaded on demand. In embedded mode, kernel_load_completed
88           is ignored, and all modules are loaded during system start.
89
90         {kernelProcess, Name, {Mod, Func, Args}}:
91           Starts the "kernel process" Name  by  evaluating  apply(Mod,  Func,
92           Args).  The  start  function  is to return {ok, Pid} or ignore. The
93           init process monitors the behavior of Pid and terminates the system
94           if  Pid  dies.  Kernel  processes are key components of the runtime
95           system. Users do not normally add new kernel processes.
96
97         {apply, {Mod, Func, Args}}.:
98           The init process evaluates apply(Mod, Func, Args). The system  ter‐
99           minates  if  this  results in an error. The boot procedure hangs if
100           this function never returns.
101
102   Note:
103       In an interactive system, the code loader provides  demand-driven  code
104       loading, but in an embedded system the code loader loads all code imme‐
105       diately. The same version of code is  used  in  both  cases.  The  code
106       server  calls  init:get_argument(mode)  to determine if it is to run in
107       demand mode or non-demand driven mode.
108
109

SEE ALSO

111       systools(3)
112
113
114
115Ericsson AB                        sasl 4.2                          script(5)
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