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Is there a way to define an unlimited history in Bash ?

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migrated from stackoverflow.com May 4 '10 at 12:06

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3 Answers 3

up vote 27 down vote accepted

put that into .bashrc:

export HISTFILESIZE=
export HISTSIZE=

There you go, unlimited history. Currently I have 27000 entries :)

From "man bash":

If HISTFILESIZE is not set, no truncation is performed.

That means .bash_history is never truncated

Also the same seems to apply to HISTSIZE, although I couldnt find that documented.

Another neat feature I'm going to try is this:

If the HISTTIMEFORMAT variable is set, time stamps are written to the history file, marked with the history comment character, so they may be preserved across shell sessions.

Let me know if you have tried that already...

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I had not seen the HISTTIMEFORMAT before - I can confirm that it works as expected. You can easily see it working by adding it to /etc/profile (if you want all users to have this), log out and log in again, do something like ls, then history. –  Snap Shot Sep 19 '13 at 20:38
    
This does not actually work for many cases and bash history still gets truncated. See my answer below for a more complete solution. –  fotinakis May 21 at 18:34

(re-posted from http://stackoverflow.com/a/19533853/128597)

After many large, ugly iterations and weird edge cases over the years, I now have a concise section of my .bashrc dedicated to this.

First, you must comment out or remove this section of your .bashrc (default for Ubuntu). If you don't, then certain environments (like running screen sessions) will still truncate your history:

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
# HISTSIZE=1000
# HISTFILESIZE=2000

Second, add this to the bottom of your .bashrc:

# Eternal bash history.
# ---------------------
# Undocumented feature which sets the size to "unlimited".
# http://stackoverflow.com/questions/9457233/unlimited-bash-history
export HISTFILESIZE=
export HISTSIZE=
export HISTTIMEFORMAT="[%F %T] "
# Change the file location because certain bash sessions truncate .bash_history file upon close.
# http://superuser.com/questions/575479/bash-history-truncated-to-500-lines-on-each-login
export HISTFILE=~/.bash_eternal_history
# Force prompt to write history after every command.
# http://superuser.com/questions/20900/bash-history-loss
PROMPT_COMMAND="history -a; $PROMPT_COMMAND"

Note: every command is written immediately after it's run, so if you accidentally paste a password you cannot just "kill -9 %%" to avoid the history write, you'll need to remove it manually.

Also note that each bash session will load the full history file in memory, but even if your history file grows to 10MB (which will take a long, long time) you won't notice much of an effect on your bash startup time.

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Could I put this setting globally in global bashrc so that it overrides settings for all users ? –  user01 Mar 14 at 22:06

A different concept (may not be applicable) but you can have unlimited history when using shell-sink.

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