how to easily display a base64 encoded file

I wondered, how I could achieve that on various Unix platforms, and I ran the following command on my Linux box:

$ man -k base64
base64 (1)           - base64 encode/decode data and print to standard output
MIME::Base64 (3pm)   - Encoding and decoding of base64 strings

Right the utility base64 (beloning to GNU coreutils) would do it, if it were broadly available; on AIX you can't expect GNU coreutils to be installed.

The MIME::Base64 man page shows a nice perl one-liner making use of a perl module, which is rather likely to be installed:

$ perl -MMIME::Base64 -ne 'print decode_base64($_)'