I am working in Sage 6.3.beta4 (built from the tarball) under OS X 10.9.3.
sage: version()
'Sage Version 6.3.beta4, Release Date: 2014-06-19'
To check what version of GAP, Maxima or R is included, the following works:
sage: gap.version()
'4.7.5'
sage: maxima.version()
'5.33.0'
sage: r.version()
((3, 0, 2), 'R version 3.0.2 (2013-09-25)')
but surprisingly this does not give the version of PARI, but raises an attribute error:
sage: pari.version()
AttributeError: 'sage.libs.pari.pari_instance.PariInstance' object has no attribute '__version'
It turns out that the following works:
sage: pari('version')
[2, 5, 5]
but it would be nice to access the version number for PARI in the same way as for other components.
For Singular, the naive trial as above outputs information giving the version number, followed by a Singular error.