doc: fix logging sys on log-module-command recipe

Update log-module-command recipe to ensure the logging system is not
broken by the current user environment.

Fixes #475.

.aspell.en.pws

@@ -1,4 +1,4 @@
-personal_ws-1.1 en 852
+personal_ws-1.1 en 853
 ABBRVLIST
 ActiveTcl
 Adrien
@@ -378,6 +378,7 @@ etcdir
 eu
 eval
 exe
+execLogger
 execcmdlist
 executables
 execve

NEWS.rst

@@ -141,6 +141,8 @@ Modules 5.2.0 (not yet released)
 * Add :subcmd:`stashlist` sub-command to list all stash collection files.
 * Update :subcmd:`savelist` sub-command to filter out stash collections unless
   if :option:`--all` option is set.
+* Doc: ensure current user environment does not break logging system in
+  :ref:`log-module-command` recipe. (fix issue #475)
 
 .. _Nagelfar: http://nagelfar.sourceforge.net/
 .. _ShellCheck: https://www.shellcheck.net/

doc/example/log-module-commands/siteconfig.tcl

@@ -10,6 +10,19 @@
 #   installation. Refer to the "Modulecmd startup" section in the
 #   module(1) man page to get this location.
 
+proc execLogger {msg} {
+   # ensure logger command is executed with system libs
+   if {[info exists ::env(LD_LIBRARY_PATH)]} {
+      set ORIG_LD_LIBRARY_PATH $::env(LD_LIBRARY_PATH)
+      unset ::env(LD_LIBRARY_PATH)
+   }
+   exec logger -t module $msg
+   # restore current user lib setup
+   if {[info exists ORIG_LD_LIBRARY_PATH]} {
+      set ::env(LD_LIBRARY_PATH) $ORIG_LD_LIBRARY_PATH
+   }
+}
+
 proc logModfileInterp {cmdstring code result op} {
    # parse context
    lassign $cmdstring cmdname modfile modname
@@ -32,8 +45,8 @@ proc logModfileInterp {cmdstring code result op} {
       }
 
       # produced log entry (formatted as a JSON record)
-      exec logger -t module "{ \"user\": \"[get-env USER]\", \"mode\":\
-         \"$mode\", \"module\": \"$modname\"${extra} }"
+      execLogger "{ \"user\": \"[get-env USER]\", \"mode\": \"$mode\",\
+         \"module\": \"$modname\"${extra} }"
    }
 }
 
@@ -53,8 +66,8 @@ proc logModuleCmd {cmdstring code result op} {
    if {$cmdname ne {module} || $caller ne {ml}} {
 
       # produced log entry (formatted as a JSON record)
-      exec logger -t module "{ \"user\": \"[get-env USER]\", \"cmd\":\
-         \"$cmdname\", \"args\": \"$args\" }"
+      execLogger "{ \"user\": \"[get-env USER]\", \"cmd\": \"$cmdname\",\
+         \"args\": \"$args\" }"
    }
 }
 

doc/source/cookbook/log-module-commands.rst

@@ -17,8 +17,8 @@ configuration that traces every call to a modulefile evaluation.
 .. literalinclude:: ../../example/log-module-commands/siteconfig.tcl
    :language: tcl
    :caption: siteconfig.tcl
-   :lines: 13-41
-   :lineno-start: 13
+   :lines: 26-54
+   :lineno-start: 26
 
 This code defines a ``logModfileInterp`` procedure which is set to be
 evaluated after each evaluation of the ``execute-modulefile`` procedure with
@@ -32,19 +32,28 @@ following line:
 
 .. literalinclude:: ../../example/log-module-commands/siteconfig.tcl
    :language: tcl
-   :lines: 23-24
-   :lineno-start: 23
+   :lines: 36-37
+   :lineno-start: 36
+
+In the proposed code, log entries are formatted as a JSON record which is
+convenient to push these logs in a search and analytics engine like
+`Elasticsearch`_ or `Splunk`_. Such tools help to globally monitor the whole
+set of log entries produced from thousands of computing nodes.
+
+.. literalinclude:: ../../example/log-module-commands/siteconfig.tcl
+   :language: tcl
+   :lines: 47-49
+   :lineno-start: 47
 
-In the proposed code, the :command:`logger` command is run to generate a log
-message. Log entries are formatted as a JSON record which is convenient to
-push these logs in a search and analytics engine like `Elasticsearch`_ or
-`Splunk`_. Such tools help to globally monitor the whole set of log entries
-produced from thousands of computing nodes.
+The :command:`logger` command is run to generate the log message. This is done
+through a specific ``execLogger`` procedure ensuring that the current user
+environment does not confuse :command:`logger` with unexpected version of the
+libraries it requires.
 
 .. literalinclude:: ../../example/log-module-commands/siteconfig.tcl
    :language: tcl
-   :lines: 34-36
-   :lineno-start: 34
+   :lines: 13-24
+   :lineno-start: 13
 
 Example code also defines a ``logModuleCmd`` procedure which is set to be
 evaluated after each evaluation of the ``module`` and the ``ml`` procedures
@@ -53,8 +62,8 @@ with `trace`_ Tcl command.
 .. literalinclude:: ../../example/log-module-commands/siteconfig.tcl
    :language: tcl
    :caption: siteconfig.tcl
-   :lines: 43-63
-   :lineno-start: 43
+   :lines: 56-76
+   :lineno-start: 56
 
 .. note::