How does a bash script affected by bash4 work?

Question

bash4 looks good on paper , and I think I will build it and give it a test drive.

Meanwhile...

Anyone who has taken the same care to share their experiences?

It would be especially interesting to know about problems with old bash code.

Answer 1

The bash NEWS file, reproduced here with some summary, has good information. Big new features include:

• Associative arrays : names of array members using array[name] and access using ${array[name]}
• Special ** glob pattern: match all files and directories to zero or more
• Co-processes : use the coproc keyword to start another process and then redirect its I / O to the current existing shell (or another process, if you wish)
• Case-sensitive extensions : case- insensitive match names

Answer 2

There is a document compatible document that covers all versions from bash to 4.1.

POSIX compliance tightening is one area where differences have emerged with version 3.2.