Thank you!! Why on earth isn't that the default. It always seemed weird that with multiple bash windows open, the commands from most of them weren't added to the history.
I often have three or more terminals open, doing different tasks in each; I also often have cycles of work where I'll repeat the last three commands again (three up-arrows and a return). This breaks if one terminal's commands get inserted into another terminal's history.
"Ted, the change I suggest doesn't affect the independence of your sessions as you suggest. Each shell maintains a unique history in memory so modifying the history file has no affect on running terminals. The only time the history file is read is when you start a new terminal. I recommend you try my suggestion. Really, all I am doing is eliminating the race condition that causes the bash history file to have inconsistent data.
To some degree; it depends on the amount of multitasking. I mainly care about which commands in which order when I'm looking at recent commands from that terminal; otherwise I use C-r.
My guesses are that it's on-close so you can follow the per-shell history slightly easier (rather than it being interleaved from multiple shells?), or reducing disk writes?
It is very useful just be careful when switching between shells and hitting the up arrow to get the previous command, as you may get something from another shell.
That will only happen if PROMPT_COMMAND also contains "history -c; history -r", right? "history -a" just saves it, but "history -c; history -r" clears memory history and reloads from disk.