Two versions of perl are available on the ACS cluster: perl4 and perl5.

All new work in perl should be done in perl5. The first line of all perl5 scripts should be:

#!/usr/local/bin/perl5

To view the base documentation for perl5, type the following at the ACS command prompt:

man perl5

While perl5 is largely backward-compatible with perl4, there are a few differences that prevent us from changing the default from perl4 to perl5. Generally, these have to do with perl5′s more rigorous detection of ambiguous and erroneous statements. For the time being, /usr/local/bin/perl will still invoke perl4. You should not rely on this, as it may be changed to invoke perl5 in the future.

For explicit details on the issues to be aware of when moving from perl4 to perl5, type the following at the ACS command prompt:



man perltrap