How to (not) use GPL Software
License Compatibility

There's lots of Free Software available
Different Software uses different Licenses:
Linux: GPL
glibc: LGPL
apache: Apache Software License
Perl: Artistic
ucd-snmp: BSD
If you combine (i.e. link) differently-licensed software,
check license compatibility
in case of doubt, ask legal person and/or contact software authors
authors might give you an exception or consider making licenses compatible