Upgrade manually an installed perl module

When an application requires a minimum perl module version which is not provided by installed RPM, it can be upgraded manually.
For instance, it is the case of amavis (see create a full and secured emails server), when upgrading some perl rpm packages (perl-CPAN for instance).

To upgrade CPAN perl module manually, opens a perl shell:
perl -MCPAN -e shell

Then request the "install" of the newest available perl module version. For instance:
install File::Temp

Define the current version of a perl module

To get the current version of an installed perl module, the following command can be used:
perl -le 'use MODULE_NAME; print MODULE_NAME->VERSION'
With MODULE_NAME the name of the wished perl module.

For instance with File::Temp it gives:
perl -le 'use File::Temp; print File::Temp->VERSION'

Get the list of gcc defined macro after preprocessing

It various situation, it is very useful to get the list of all defined maco after gcc preprocessing.
Particularly when porting C/C++ source code to another OS/Architecture to know what macro to use to identify it.

A simple way is to use gcc with the following options:
-E to end after preprocessing step,
-dM to print all defined macros.

For instance to known the "default" macros, use those options with a simple source code file "test.c" defining a main function:
gcc -E -dM test.c