Bash history timestamps broken when called from command string in MacOS

Question

I've got a weird one here. I'm writing a program that needs access to bash history. I had a look at parsing the .bash_history (or .bash_eternal_history in my config) file, but realized the heavy lifting had already been done by the history builtin.

Some contents of my history file look like this. While I could parse this myself, I would prefer to rely on history's standardized parser as it already deals with edge-case multiline commands, timestamps, histfile formats, and works cross-platform.

#1587920724
echo test
#1587920725
echo test2
#1587920729
touch file
#1587920731
rm file
#1587920732
history

When typing the history command, I get a nice list of timestamped history, as follows:

 5083  [2020-04-26 18:05:24] echo test
 5084  [2020-04-26 18:05:25] echo test2
 5085  [2020-04-26 18:05:29] touch file
 5086  [2020-04-26 18:05:31] rm file
 5087  [2020-04-26 18:05:32] history

As history is a shell builtin, I need to run it through a bash command string in my program. However, when running the command bash -ic 'history -r; history' , I am greeted with this:

10159  [2020-04-26 18:08:35] #1587920724
10160  [2020-04-26 18:08:35] echo test
10161  [2020-04-26 18:08:35] #1587920725
10162  [2020-04-26 18:08:35] echo test2
10163  [2020-04-26 18:08:35] #1587920729
10164  [2020-04-26 18:08:35] touch file
10165  [2020-04-26 18:08:35] #1587920731
10166  [2020-04-26 18:08:35] rm file
10167  [2020-04-26 18:08:35] #1587920732
10168  [2020-04-26 18:08:35] history

The commented timestamps are printed out as if they were commands, and everything has the same timestamp (the time I ran the command).

The strange part is, on Linux, bash -ic 'history -r; history' produces exactly the same output as history, in the regular format with correct timestamps, which is what I expected to happen.

I guess I would like to know:

1. Why is the output of the two commands different in MacOS but the same in Linux?
2. How can I achieve the correct output from a command string? (I am running the command from a Python script)
3. Am I going about this in the wrong way? My original aim was to get the full timestamped bash history from within a Python program (without doing something external like history > history.txt && ./script.py or history | ./script.py).

Thanks :)

Additional information

• MacOS version: 10.14.6 Mojave
• MacOS bash version: 3.2.57
• History config: Eternal bash history
• Linux version: Linux Mint 19.2
• Linux bash version: 4.4.20

Answer 1

I can confirm the issue.

Yes, there seems to be a problem with bash version 3.2.57 and before in that they don't recognize the timestamps in the history file. I was unable to find the specific change in the bash changes file. You probably need to upgrade bash to a newer version (4+).