In zsh, I want to have unlimited history. I set HISTSIZE=, which works in bash. Now I import an old history

mv old_history .history

which is pretty big

wc -l .history
43562 .history

If I now close and start zsh again, I see

wc -l .history
32234 .history

Can't I have unlimited history in zsh?


There is the limit and the possibilities of your machines.

setopt BANG_HIST                 # Treat the '!' character specially during expansion.
setopt EXTENDED_HISTORY          # Write the history file in the ":start:elapsed;command" format.
setopt INC_APPEND_HISTORY        # Write to the history file immediately, not when the shell exits.
setopt SHARE_HISTORY             # Share history between all sessions.
setopt HIST_EXPIRE_DUPS_FIRST    # Expire duplicate entries first when trimming history.
setopt HIST_IGNORE_DUPS          # Don't record an entry that was just recorded again.
setopt HIST_IGNORE_ALL_DUPS      # Delete old recorded entry if new entry is a duplicate.
setopt HIST_FIND_NO_DUPS         # Do not display a line previously found.
setopt HIST_IGNORE_SPACE         # Don't record an entry starting with a space.
setopt HIST_SAVE_NO_DUPS         # Don't write duplicate entries in the history file.
setopt HIST_REDUCE_BLANKS        # Remove superfluous blanks before recording entry.
setopt HIST_VERIFY               # Don't execute immediately upon history expansion.
setopt HIST_BEEP                 # Beep when accessing nonexistent history.

From the ZSH Mailing list:

You should determine how much memory you have, how much of it you can allow to be occupied by the history (AFAIK it is always fully loaded into memory) and act accordingly. Removing the limit is not wiser as it leaves you with an idea that there is no limit while it is always limited by available resources.

Or if you do not think you will ever hit a problem with resource exhaustion you can just set HISTSIZE to LONG_MAX from limits.h: it is the maximum number HISTSIZE can have.

Which explain the Gentoo solution:

export HISTSIZE=2000
export HISTFILE="$HOME/.history"

History won't be saved without the following command:


To prevent history from recording duplicated entries (such as ls -l entered many times during single shell session), you can set the hist_ignore_all_dups option:

setopt hist_ignore_all_dups

A useful trick to prevent particular entries from being recorded into a history by preceding them with at least one space.

setopt hist_ignore_space
  • I don't see how that answers my question. The size of my history file is 683 kB, surely not too large for my memory? – pfnuesel Apr 2 '16 at 15:09
  • 2
    user $export HISTSIZE=99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999 will be out of the possibilities of your computer. You have to set that number to fit as best as possible to your wish and computer possibilities. – aurelien Apr 2 '16 at 15:11
  • I can set it to 50000, but that won't fix my problem. – pfnuesel Apr 2 '16 at 15:12
  • ZSH author explain in the mailing list that limit and the point that unlimited is not possible because of the hardware and Gentoo set it to 2000 to fit it to every computer user. – aurelien Apr 2 '16 at 15:13
  • Have you tried as they says with the 50000? user $export HISTSIZE=50000 ; user $export HISTFILE="$HOME/.history" ; user $export SAVEHIST=$HISTSIZE – aurelien Apr 2 '16 at 15:14

You need to set both HISTSIZE and SAVEHIST. They indicate how many lines of history to keep in memory and how many lines to keep in the history file, respectively.

I don't think zsh has a setting that means “infinite”, but for all practical purpose, one billion is infinite, while remaining machine-representable on 32-bit machines.

  • Should I have to worry about keeping such a large number of lines in memory slowing down my computer? – becko Jan 11 '18 at 17:58
  • 5
    You are not going to type enough history lines in your life time to slow down a 2010s PC. – Gilles Jan 11 '18 at 18:56

The problem was not with zsh or my .zshrc, but with my history. There were some oddball entries like


that confused zsh and everything after these entries got truncated. I don't know what character ^@ corresponds to, or how these entries ended up in my history, but removing them fixed the problem.

  • which terminal and editor do you use? – aurelien Apr 2 '16 at 16:06
  • because the question now, is, does that will come back once again later? – aurelien Apr 2 '16 at 16:07
  • terminology and vim. – pfnuesel Apr 2 '16 at 16:11
  • 1
    ^@ is the ASCII NUL (\0) character. – muru Apr 3 '16 at 1:22
  • 6
    The ^@^@^@^@ characters are nulls, and they frequently show up when two programs try writing to the same file at the same time, and aren't using atomic writes (eg. they're buffered writes) or locking. Or it can be caused by filesystem corruption, bad restoration from backup, or similar. – user222658 Mar 24 '17 at 18:50

I was having a problem with history being capped at 10000 until I realized oh-my-zsh was setting its own HISTSIZE and SAVEHIST values. TL;DR, make sure to put the lines at the bottom of your .zshrc.

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