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I've tried to search in ~/.bash_history for my recent commands while in a terminal session but they just weren't there. I guess this is because I have multiple terminal sessions open.

Is there a way that I can sync (ie. sync-push or sync-write-out) the current terminal session's command history into the bash_history file (without closing the session and losing that environment)?

(It would be remotely similar in idea to how the sync command stores the file-system modifications on some embedded systems.)

I imagine I could set up bash to preserve multiple session history but the ability to push the current history buffer would still be useful in scenarios when you are working on a new machine and you accidentally forgot to set up bash the way you may would have wanted.

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I've tried history -a shell builtin command but somehow I now get 'permission denied' on the .bash_history file, after that. –  naxa May 22 at 11:30

1 Answer 1

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Add this line to .bashrc:

export PROMPT_COMMAND="history -a; history -n"

Open new termial and check.

Explanation

  • history -a append new history lines to history file.
  • history -n tell bash to read lines that is not read from history file to current history list of session.
  • PROMPT_COMMAND: contents of this variable is run as regular command before bash show prompt. So every time you execute a command, after that, history -a; history -n is executed, you bash history is synced.
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thanks! I don't know why did I get permission denied before but with new terminals now this seems to work as expected! I guess I should normally be able to use history -a in a terminal with unmodified bashrc too. –  naxa May 22 at 11:40
    
when do one have to start to worry about the performance implications of this? (I'm thinking about low-end devices, not sure how big overhead this makes.) –  naxa May 22 at 11:42
    
Also you might already have a prompt command, in this case it is better to use export PROMPT_COMMAND="${PROMPT_COMMAND};history -a; history -n" –  Fabian May 22 at 13:02

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