1release_handler(3)         Erlang Module Definition         release_handler(3)
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4

NAME

6       release_handler - Unpacking and Installation of Release Packages
7

DESCRIPTION

9       The  release  handler process belongs to the SASL application, which is
10       responsible for release handling, that is, unpacking, installation, and
11       removal of release packages.
12
13       An  introduction  to release handling and an example is provided in OTP
14       Design Principles in System Documentation.
15
16       A release package is a compressed tar file containing code for  a  cer‐
17       tain  version  of  a release, created by calling systools:make_tar/1,2.
18       The release package is to be located in the $ROOT/releases directory of
19       the  previous  version  of the release, where $ROOT is the installation
20       root directory, code:root_dir().  Another  releases  directory  can  be
21       specified using the SASL configuration parameter releases_dir or the OS
22       environment variable RELDIR. The release handler must have write access
23       to  this  directory to install the new release. The persistent state of
24       the release handler is stored there in a file called RELEASES.
25
26       A release package is always to contain:
27
28         * A release resource file, Name.rel
29
30         * A boot script, Name.boot
31
32       The .rel file contains information about the release:  its  name,  ver‐
33       sion, and which ERTS and application versions it uses.
34
35       A release package can also contain:
36
37         * A release upgrade file, relup
38
39         * A system configuration file, sys.config
40
41         * A system configuration source file, sys.config.src
42
43       The  relup  file  contains instructions for how to upgrade to, or down‐
44       grade from, this version of the release.
45
46       The release package can be  unpacked,  which  extracts  the  files.  An
47       unpacked  release  can  be installed. The currently used version of the
48       release is then upgraded or downgraded  to  the  specified  version  by
49       evaluating the instructions in the relup file. An installed release can
50       be made permanent. Only one permanent release can exist in the  system,
51       and  this  release  is  used  if  the system is restarted. An installed
52       release, except the permanent one, can be removed. When  a  release  is
53       removed, all files belonging to that release only are deleted.
54
55       Each release version has a status, which can be unpacked, current, per‐
56       manent, or old. There is always one latest release,  which  either  has
57       status  permanent (normal case) or current (installed, but not yet made
58       permanent). The meaning of the status values  are  illustrated  in  the
59       following table:
60
61               Status     Action                NextStatus
62               -------------------------------------------
63               -          unpack                unpacked
64               unpacked   install               current
65                          remove                -
66               current    make_permanent        permanent
67                          install other         old
68                          remove                -
69               permanent  make other permanent  old
70                          install               permanent
71               old        reboot_old            permanent
72                          install               current
73                          remove                -
74
75       The  release  handler  process  is a locally registered process on each
76       node. When a release is installed in a distributed system, the  release
77       handler  on  each  node must be called. The release installation can be
78       synchronized between nodes. From an operator view, it can  be  unsatis‐
79       factory to specify each node. The aim is to install one release package
80       in the system, no matter how many nodes there are.  It  is  recommended
81       that  software  management functions are written that take care of this
82       problem. Such a function can have knowledge of the system architecture,
83       so  it can contact each individual release handler to install the pack‐
84       age.
85
86       For release handling to work properly, the  runtime  system  must  know
87       which  release  it  is running. It must also be able to change (in run‐
88       time) which boot script and system configuration file are to be used if
89       the  system is restarted. This is taken care of automatically if Erlang
90       is started as an embedded system. Read about this in Embedded System in
91       System  Documentation.  In  this  case,  the  system configuration file
92       sys.config is mandatory.
93
94       The installation of a new release can restart the system. Which program
95       to  use  is  specified  by  the SASL configuration parameter start_prg,
96       which defaults to $ROOT/bin/start.
97
98       The emulator restart on Windows NT expects that the system  is  started
99       using  the erlsrv program (as a service). Furthermore, the release han‐
100       dler expects that the service is named NodeName_Release, where NodeName
101       is the first part of the Erlang node name (up to, but not including the
102       "@") and Release is the current release version.  The  release  handler
103       furthermore  expects  that a program like start_erl.exe is specified as
104       "machine" to erlsrv. During upgrading with restart, a  new  service  is
105       registered and started. The new service is set to automatic and the old
106       service is removed when the new release is made permanent.
107
108       The release handler at a node running on a diskless machine, or with  a
109       read-only file system, must be configured accordingly using the follow‐
110       ing SASL configuration parameters (for details, see sasl(6)):
111
112         masters:
113           This node uses some master nodes to store and fetch release  infor‐
114           mation.  All  master  nodes  must  be  operational whenever release
115           information is written by this node.
116
117         client_directory:
118           The client_directory in the directory structure of the master nodes
119           must be specified.
120
121         static_emulator:
122           This  parameter  specifies  if  the  Erlang  emulator is statically
123           installed at the client node. A node with a static emulator  cannot
124           dynamically  switch  to a new emulator, as the executable files are
125           statically written into memory.
126
127       The release handler can also be used  to  unpack  and  install  release
128       packages  when  not  running  Erlang as an embedded system. However, in
129       this case the user must somehow ensure that correct  boot  scripts  and
130       configuration files are used if the system must be restarted.
131
132       Functions are provided for using another file structure than the struc‐
133       ture defined in OTP. These functions can be  used  to  test  a  release
134       upgrade locally.
135

EXPORTS

137       check_install_release(Vsn) -> {ok, OtherVsn, Descr} | {error, Reason}
138       check_install_release(Vsn,Opts) -> {ok, OtherVsn, Descr} | {error, Rea‐
139       son}
140
141              Types:
142
143                 Vsn = OtherVsn = string()
144                 Opts = [Opt]
145                 Opt = purge
146                 Descr = term()
147                 Reason = term()
148
149              Checks if the specified  version  Vsn  of  the  release  can  be
150              installed.  The  release  must  not  have status current. Issues
151              warnings if relup file or sys.config is not  present.  If  relup
152              file  is present, its contents are checked and {error,Reason} is
153              returned if an error is found. Also  checks  that  all  required
154              applications  are  present  and that all new code can be loaded;
155              {error,Reason} is returned if an error is found.
156
157              Evaluates   all   instructions    that    occur    before    the
158              point_of_no_return instruction in the release upgrade script.
159
160              Returns  the  same as install_release/1. Descr defaults to "" if
161              no relup file is found.
162
163              If option purge is specified, all old code  that  can  be  soft-
164              purged  is  purged  after all other checks are successfully com‐
165              pleted. This  can  be  useful  to  reduce  the  time  needed  by
166              install_release/1.
167
168       create_RELEASES(Root, RelDir, RelFile, AppDirs) -> ok | {error, Reason}
169
170              Types:
171
172                 Root = RelDir = RelFile = string()
173                 AppDirs = [{App, Vsn, Dir}]
174                  App = atom()
175                  Vsn = Dir = string()
176                 Reason = term()
177
178              Creates  an initial RELEASES file to be used by the release han‐
179              dler. This file must exist to install new releases.
180
181              Root is the root of the installation ($ROOT) as  described  ear‐
182              lier.  RelDir  is the directory where the RELEASES file is to be
183              created (normally $ROOT/releases). RelFile is the  name  of  the
184              .rel  file  that  describes  the  initial release, including the
185              extension .rel.
186
187              AppDirs can be used to specify from where the  modules  for  the
188              specified  applications  are to be loaded. App is the name of an
189              application, Vsn is the version, and Dir  is  the  name  of  the
190              directory  where  App-Vsn  is located. The corresponding modules
191              are to be located under Dir/App-Vsn/ebin.  The  directories  for
192              applications  not specified in AppDirs are assumed to be located
193              in $ROOT/lib.
194
195       install_file(Vsn, File) -> ok | {error, Reason}
196
197              Types:
198
199                 Vsn = File = string()
200                 Reason = term()
201
202              Installs a release-dependent file in the release structure.  The
203              release-dependent  file  must be in the release structure when a
204              new release is installed: start.boot, relup, and sys.config.
205
206              The function can be called, for example, when  these  files  are
207              generated  at  the  target.  The  function is to be called after
208              set_unpacked/2 has been called.
209
210       install_release(Vsn) -> {ok, OtherVsn, Descr} | {error, Reason}
211       install_release(Vsn,  [Opt])  ->  {ok,   OtherVsn,   Descr}   |   {con‐
212       tinue_after_restart, OtherVsn, Descr} | {error, Reason}
213
214              Types:
215
216                 Vsn = OtherVsn = string()
217                 Opt = {error_action, Action} | {code_change_timeout, Timeout}
218                  | {suspend_timeout, Timeout} | {update_paths, Bool}
219                  Action = restart | reboot
220                  Timeout = default | infinity | pos_integer()
221                  Bool = boolean()
222                 Descr = term()
223                 Reason  =  {illegal_option, Opt} | {already_installed, Vsn} |
224                 {change_appl_data,  term()}  |  {missing_base_app,  OtherVsn,
225                 App} | {could_not_create_hybrid_boot, term()} | term()
226                 App = atom()
227
228              Installs  the  specified version Vsn of the release. Looks first
229              for a relup file for Vsn and a script {UpFromVsn,Descr1,Instruc‐
230              tions1}  in this file for upgrading from the current version. If
231              not found, the function looks for a relup file for  the  current
232              version and a script {Vsn,Descr2,Instructions2} in this file for
233              downgrading to Vsn.
234
235              If a script is found, the first thing that happens is  that  the
236              application  specifications  are  updated  according to the .app
237              files and sys.config belonging to the release version Vsn.
238
239              After the application  specifications  have  been  updated,  the
240              instructions  in  the  script  are  evaluated  and  the function
241              returns {ok,OtherVsn,Descr} if successful.  OtherVsn  and  Descr
242              are  the  version  (UpFromVsn or Vsn) and description (Descr1 or
243              Descr2) as specified in the script.
244
245              If {continue_after_restart,OtherVsn,Descr} is returned, the emu‐
246              lator is restarted before the upgrade instructions are executed.
247              This occurs if the emulator or any of the  applications  Kernel,
248              STDLIB,  or SASL are updated. The new emulator version and these
249              core applications execute  after  the  restart.  For  all  other
250              applications  the  old  versions  are started and the upgrade is
251              performed as normal by executing the upgrade instructions.
252
253              If a recoverable error occurs, the function returns  {error,Rea‐
254              son}  and  the original application specifications are restored.
255              If a non-recoverable error occurs, the system is restarted.
256
257              Options:
258
259                error_action:
260                  Defines if the node is to be restarted  (init:restart())  or
261                  rebooted  (init:reboot())  if  there  is an error during the
262                  installation. Default is restart.
263
264                code_change_timeout:
265                  Defines the time-out for all calls to sys:change_code. If no
266                  value  is  specified  or  default  is specified, the default
267                  value defined in sys is used.
268
269                suspend_timeout:
270                  Defines the time-out for all calls  to  sys:suspend.  If  no
271                  value is specified, the values defined by the Timeout param‐
272                  eter of the upgrade or suspend  instructions  are  used.  If
273                  default  is  specified,  the default value defined in sys is
274                  used.
275
276                {update_paths,Bool}:
277                  Indicates if all application code paths are  to  be  updated
278                  (Bool==true) or if only code paths for modified applications
279                  are to be updated (Bool==false, default).  This  option  has
280                  only  effect  for  other  application  directories  than the
281                  default $ROOT/lib/App-Vsn, that is, application  directories
282                  specified in argument AppDirs in a call to create_RELEASES/4
283                  or set_unpacked/2.
284
285                  Example:
286
287                  In the current version CurVsn of a release, the  application
288                  directory  of  myapp  is  $ROOT/lib/myapp-1.0. A new version
289                  NewVsn is unpacked  outside  the  release  handler  and  the
290                  release  handler  is informed about this with a call as fol‐
291                  lows:
292
293                release_handler:set_unpacked(RelFile, [{myapp,"1.0","/home/user"},...]).
294                => {ok,NewVsn}
295
296                  If NewVsn is installed with option {update_paths,true}, then
297                  code:lib_dir(myapp) returns /home/user/myapp-1.0.
298
299          Note:
300              Installing a new release can be time consuming if there are many
301              processes in the system. The reason is that each process must be
302              checked  for  references  to  old  code  before  a module can be
303              purged. This check can lead to garbage collections  and  copying
304              of data.
305
306              To  speed  up  the  execution  of  install_release,  first  call
307              check_install_release, using option purge. This  does  the  same
308              check  for  old  code. Then purges all modules that can be soft-
309              purged. The purged modules do then no longer have any old  code,
310              and install_release does not need to do the checks.
311
312              This  does  not  reduce the overall time for the upgrade, but it
313              allows checks and purge to be executed in the background  before
314              the real upgrade is started.
315
316
317          Note:
318              When  upgrading  the emulator from a version older than OTP R15,
319              an attempt is made to load new application beam  code  into  the
320              old  emulator.  Sometimes  the new beam format cannot be read by
321              the old emulator, so the code loading  fails  and  the  complete
322              upgrade  is terminated. To overcome this problem, the new appli‐
323              cation code is to be compiled with the old  emulator.  For  more
324              information  about  emulator  upgrade from pre OTP R15 versions,
325              see Design Principles in System Documentation.
326
327
328       make_permanent(Vsn) -> ok | {error, Reason}
329
330              Types:
331
332                 Vsn = string()
333                 Reason = {bad_status, Status} | term()
334
335              Makes the specified release version Vsn permanent.
336
337       remove_release(Vsn) -> ok | {error, Reason}
338
339              Types:
340
341                 Vsn = string()
342                 Reason = {permanent, Vsn} | client_node | term()
343
344              Removes a release and its files from  the  system.  The  release
345              must  not  be  the permanent release. Removes only the files and
346              directories not in use by another release.
347
348       reboot_old_release(Vsn) -> ok | {error, Reason}
349
350              Types:
351
352                 Vsn = string()
353                 Reason = {bad_status, Status} | term()
354
355              Reboots the system by making  the  old  release  permanent,  and
356              calls init:reboot() directly. The release must have status old.
357
358       set_removed(Vsn) -> ok | {error, Reason}
359
360              Types:
361
362                 Vsn = string()
363                 Reason = {permanent, Vsn} | term()
364
365              Makes  it  possible  to  handle  removal of releases outside the
366              release handler. Tells the release handler that the  release  is
367              removed  from  the  system.  This  function  does not delete any
368              files.
369
370       set_unpacked(RelFile, AppDirs) -> {ok, Vsn} | {error, Reason}
371
372              Types:
373
374                 RelFile = string()
375                 AppDirs = [{App, Vsn, Dir}]
376                  App = atom()
377                  Vsn = Dir = string()
378                 Reason = term()
379
380              Makes it possible to handle unpacking of  releases  outside  the
381              release  handler.  Tells the release handler that the release is
382              unpacked. Vsn  is  extracted  from  the  release  resource  file
383              RelFile.
384
385              AppDirs  can  be  used to specify from where the modules for the
386              specified applications are to be loaded. App is the name  of  an
387              application,  Vsn  is  the  version,  and Dir is the name of the
388              directory where App-Vsn is located.  The  corresponding  modules
389              are  to  be  located under Dir/App-Vsn/ebin. The directories for
390              applications not specified in AppDirs are assumed to be  located
391              in $ROOT/lib.
392
393       unpack_release(Name) -> {ok, Vsn} | {error, Reason}
394
395              Types:
396
397                 Name = Vsn = string()
398                 Reason = client_node | term()
399
400              Unpacks  a  release  package Name.tar.gz located in the releases
401              directory.
402
403              Performs some checks on the package, for  example,  checks  that
404              all mandatory files are present, and extracts its contents.
405
406       which_releases() -> [{Name, Vsn, Apps, Status}]
407
408              Types:
409
410                 Name = Vsn = string()
411                 Apps = ["App-Vsn"]
412                 Status = unpacked | current | permanent | old
413
414              Returns all releases known to the release handler.
415
416       which_releases(Status) -> [{Name, Vsn, Apps, Status}]
417
418              Types:
419
420                 Name = Vsn = string()
421                 Apps = ["App-Vsn"]
422                 Status = unpacked | current | permanent | old
423
424              Returns  all  releases,  known to the release handler, of a spe‐
425              cific status.
426

APPLICATION UPGRADE/DOWNGRADE

428       The following functions can be used to test upgrade  and  downgrade  of
429       single   applications   (instead  of  upgrading/downgrading  an  entire
430       release). A script corresponding to the instructions in the relup  file
431       is  created  on-the-fly,  based on the .appup file for the application,
432       and evaluated exactly in the same way as release_handler does.
433
434   Warning:
435       These functions are primarily intended for simplified testing of .appup
436       files.  They  are  not  run  within  the context of the release_handler
437       process. They must  therefore  not  be  used  together  with  calls  to
438       install_release/1,2, as this causes the release_handler to end up in an
439       inconsistent state.
440
441       No persistent information is updated, so these functions can be used on
442       any  Erlang node, embedded or not. Also, using these functions does not
443       affect which code is loaded if there is a reboot.
444
445       If the upgrade or downgrade fails, the application can  end  up  in  an
446       inconsistent state.
447
448

EXPORTS

450       upgrade_app(App,  Dir)  ->  {ok, Unpurged} | restart_emulator | {error,
451       Reason}
452
453              Types:
454
455                 App = atom()
456                 Dir = string()
457                 Unpurged = [Module]
458                  Module = atom()
459                 Reason = term()
460
461              Upgrades an application App from the current version  to  a  new
462              version located in Dir according to the .appup file.
463
464              App  is  the name of the application, which must be started. Dir
465              is the new library directory of App. The  corresponding  modules
466              as  well  as  the  .app and .appup files are to be located under
467              Dir/ebin.
468
469              The function looks in the .appup  file  and  tries  to  find  an
470              upgrade script from the current version of the application using
471              upgrade_script/2.    This    script    is    evaluated     using
472              eval_appup_script/4,    exactly    in    the    same    way   as
473              install_release/1,2 does.
474
475              Returns one of the following:
476
477                * {ok, Unpurged} if evaluating the script is successful, where
478                  Unpurged is a list of unpurged modules
479
480                * restart_emulator  if  this instruction is encountered in the
481                  script
482
483                * {error, Reason} if an error occurred when finding or  evalu‐
484                  ating the script
485
486              If  the restart_new_emulator instruction is found in the script,
487              upgrade_app/2 returns {error,restart_new_emulator}. This because
488              restart_new_emulator  requires  a new version of the emulator to
489              be started before the rest of the upgrade  instructions  can  be
490              executed, and this can only be done by install_release/1,2.
491
492       downgrade_app(App, Dir) ->
493       downgrade_app(App,  OldVsn, Dir) -> {ok, Unpurged} | restart_emulator |
494       {error, Reason}
495
496              Types:
497
498                 App = atom()
499                 Dir = OldVsn = string()
500                 Unpurged = [Module]
501                  Module = atom()
502                 Reason = term()
503
504              Downgrades an application App from the current version to a pre‐
505              vious  version  OldVsn  located  in  Dir according to the .appup
506              file.
507
508              App is the name of the application, which must be started.  Old‐
509              Vsn  is  the  previous application version and can be omitted if
510              Dir is of the format "App-OldVsn". Dir is the library  directory
511              of  the  previous  version of App. The corresponding modules and
512              the old .app file are to be located under Dir/ebin.  The  .appup
513              file  is  to  be  located  in  the ebin directory of the current
514              library directory of the application (code:lib_dir(App)).
515
516              The function looks in the .appup file and tries to find a  down‐
517              grade  script  to  the previous version of the application using
518              downgrade_script/3.   This    script    is    evaluated    using
519              eval_appup_script/4,    exactly    in    the    same    way   as
520              install_release/1,2 does.
521
522              Returns one of the following:
523
524                * {ok, Unpurged} if evaluating the script is successful, where
525                  Unpurged is a list of unpurged modules
526
527                * restart_emulator  if  this instruction is encountered in the
528                  script
529
530                * {error, Reason} if an error occurred when finding or  evalu‐
531                  ating the script
532
533       upgrade_script(App, Dir) -> {ok, NewVsn, Script}
534
535              Types:
536
537                 App = atom()
538                 Dir = string()
539                 NewVsn = string()
540                 Script = Instructions
541
542              Tries  to  find  an  application upgrade script for App from the
543              current version to a new version located in Dir.
544
545              The   upgrade   script   can    then    be    evaluated    using
546              eval_appup_script/4.  It  is  recommended  to  use upgrade_app/2
547              instead, but this function (upgrade_script) is useful to inspect
548              the contents of the script.
549
550              App  is  the name of the application, which must be started. Dir
551              is the new library directory of App. The  corresponding  modules
552              as  well  as  the  .app and .appup files are to be located under
553              Dir/ebin.
554
555              The function looks in the .appup  file  and  tries  to  find  an
556              upgrade  script from the current application version. High-level
557              instructions  are  translated  to  low-level  instructions.  The
558              instructions  are sorted in the same manner as when generating a
559              relup file.
560
561              Returns {ok, NewVsn, Script} if successful, where NewVsn is  the
562              new application version. For details about Script, see appup(4).
563
564              Failure: If a script cannot be found, the function fails with an
565              appropriate error reason.
566
567       downgrade_script(App, OldVsn, Dir) -> {ok, Script}
568
569              Types:
570
571                 App = atom()
572                 OldVsn = Dir = string()
573                 Script = Instructions
574
575              Tries to find an application downgrade script for App  from  the
576              current version to a previous version OldVsn located in Dir.
577
578              The    downgrade    script   can   then   be   evaluated   using
579              eval_appup_script/4. It is recommended to use  downgrade_app/2,3
580              instead,  but  this  function  (downgrade_script)  is  useful to
581              inspect the contents of the script.
582
583              App is the name of the application, which must be  started.  Dir
584              is the previous library directory of App. The corresponding mod‐
585              ules and the old .app file are to be located under Dir/ebin. The
586              .appup  file  is to be located in the ebin directory of the cur‐
587              rent library directory of the application (code:lib_dir(App)).
588
589              The function looks in the .appup file and tries to find a  down‐
590              grade  script  from  the current application version. High-level
591              instructions  are  translated  to  low-level  instructions.  The
592              instructions  are sorted in the same manner as when generating a
593              relup file.
594
595              Returns {ok, Script} if successful. For  details  about  Script,
596              see appup(4).
597
598              Failure: If a script cannot be found, the function fails with an
599              appropriate error reason.
600
601       eval_appup_script(App,  ToVsn,  ToDir,  Script)  ->  {ok,  Unpurged}  |
602       restart_emulator | {error, Reason}
603
604              Types:
605
606                 App = atom()
607                 ToVsn = ToDir = string()
608                 Script
609                   See upgrade_script/2, downgrade_script/3
610                 Unpurged = [Module]
611                  Module = atom()
612                 Reason = term()
613
614              Evaluates an application upgrade or downgrade script Script, the
615              result  from  calling  upgrade_script/2  or  downgrade_script/3,
616              exactly in the same way as install_release/1,2 does.
617
618              App is the name of the application, which must be started. ToVsn
619              is the version to be upgraded/downgraded to, and  ToDir  is  the
620              library  directory of this version. The corresponding modules as
621              well as the .app and  .appup  files  are  to  be  located  under
622              Dir/ebin.
623
624              Returns one of the following:
625
626                * {ok, Unpurged} if evaluating the script is successful, where
627                  Unpurged is a list of unpurged modules
628
629                * restart_emulator if this instruction is encountered  in  the
630                  script
631
632                * {error,  Reason} if an error occurred when finding or evalu‐
633                  ating the script
634
635              If the restart_new_emulator instruction is found in the  script,
636              eval_appup_script/4  returns  {error,restart_new_emulator}. This
637              because restart_new_emulator requires a new version of the  emu‐
638              lator  to be started before the rest of the upgrade instructions
639              can   be   executed,   and   this   can   only   be   done    by
640              install_release/1,2.
641

TYPICAL ERROR REASONS

643         {bad_masters, Masters}:
644           The master nodes Masters are not alive.
645
646         {bad_rel_file, File}:
647           Specified  .rel file File cannot be read or does not contain a sin‐
648           gle term.
649
650         {bad_rel_data, Data}:
651           Specified .rel file does not contain a recognized release  specifi‐
652           cation, but another term Data.
653
654         {bad_relup_file, File}:
655           Specified relup file Relup contains bad data.
656
657         {cannot_extract_file, Name, Reason}:
658           Problems   when  extracting  from  a  tar  file,  erl_tar:extract/2
659           returned {error, {Name, Reason}}.
660
661         {existing_release, Vsn}:
662           Specified release version Vsn is already in use.
663
664         {Master, Reason, When}:
665           Some operation, indicated by the term When, failed  on  the  master
666           node Master with the specified error reason Reason.
667
668         {no_matching_relup, Vsn, CurrentVsn}:
669           Cannot  find  a script for upgrading/downgrading between CurrentVsn
670           and Vsn.
671
672         {no_such_directory, Path}:
673           The directory Pathdoes not exist.
674
675         {no_such_file, Path}:
676           The path Path (file or directory) does not exist.
677
678         {no_such_file, {Master, Path}}:
679           The path Path (file or directory) does not exist at the master node
680           Master.
681
682         {no_such_release, Vsn}:
683           The specified release version Vsn does not exist.
684
685         {not_a_directory, Path}:
686           Path exists but is not a directory.
687
688         {Posix, File}:
689           Some  file  operation  failed for File. Posix is an atom named from
690           the Posix error codes, such  as  enoent,  eacces,  or  eisdir.  See
691           file(3) in Kernel.
692
693         Posix:
694           Some file operation failed, as for the previous item in the list.
695

SEE ALSO

697       OTP  Design Principles, config(4), rel(4), relup(4), script(4), sys(3),
698       systools(3)
699
700
701
702Ericsson AB                       sasl 3.4.1                release_handler(3)
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