Thanks for the clarification Ralph.
Best regards,
Behrang Saeedzadeh
On 4 January 2018 at 13:27, Ralph Goers <ralph.go...@dslextreme.com> wrote:
> When the configuration is read all variables are resolved, so every
> variable with a single $ will be replaced with its value. When a variable
> needs to be resolved at run time you must use 2 $ characters. The first
> will be stripped off leaving the variable reference. That property will
> then be evaluated at the appropriate time.
>
> In the configuration below $${env:USER} would be evaluated for each log
> event. However, since “env” means it is an environment variable it is
> unlikely this value will change at runtime so it could have been specified
> with a single $. If it had been $${mdc:USER} then the USER variable from
> the thread context at the time the log event is processed would be
> substituted.
>
> Ralph
>
> > On Jan 3, 2018, at 5:40 PM, Behrang Saeedzadeh <behran...@gmail.com>
> wrote:
> >
> > From the docs, $$ inside the <pattern> element:
> >
> >
> > 1. <File name="Application" fileName="application.log">
> > 2. <PatternLayout>
> > 3. <pattern>%d %p %c{1.} [%t] $${env:USER} %m%n</pattern>
> > 4. </PatternLayout>
> > 5. </File>
> >
> >
> > Also from the docs, $ inside the header attribute:
> >
> >
> > 1. <File name="Application" fileName="application.log">
> > 2. <PatternLayout header="${java:runtime} - ${java:vm} - ${java:os}">
> > 3. <Pattern>%d %m%n</Pattern>
> > 4. </PatternLayout>
> > 5. </File>
> >
> >
> > I just read the docs on property substitution and how StrLookup treat
> > variables with multiple leading '$' characters, but it is not obvious to
> me
> > why in the two examples above, in one example two leading $ signs are
> used,
> > and in the other only one $ is used.
> >
> > Best regards,
> > Behrang Saeedzadeh
>
>
>
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