zsh-histdb

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Artifact e019d65f080ddcad2b20550fb37b61a5ed900b10762ce67a5bee0ef5f21bb23e:


#+TITLE:ZSH History Database

This is a small bit of zsh code that stores your history into a sqlite3 database.
It improves on the normal history by storing, for each history command:

- The start and stop times of the command
- The working directory where the command was run
- The hostname of the machine
- A unique per-host session ID, so history from several sessions is not confused
- The exit status of the command

It is also possible to merge multiple history databases together without conflict, so long as all your machines have different hostnames.

* Installation

You will need ~sqlite3~ and the usual coreutils commands installed on your ~PATH~.
To load and activate history recording you need to source ~sqlite-history.zsh~ from your shell in your zsh startup files.

If you want the history to contain correct timing information, you will also need to source ~history-timer.zsh~ and run

#+BEGIN_SRC zsh
autoload -Uz add-zsh-hook
add-zsh-hook preexec _start_timer
add-zsh-hook precmd  _stop_timer
#+END_SRC

in your zsh startup files.

* Querying history
You can query the history with the ~histdb~ command.
With no arguments it will print one screenful of history on the current host.

With arguments, it will print history lines matching their concatenation.

For wildcards within a history line, you can use the ~%~ character, which is like the shell glob ~*~, so ~histdb this%that~ will match any history line containing ~this~ followed by ~that~ with zero or more characters in-between.

To search on particular hosts, directories, sessions, or time periods, see the help with ~histdb --help~.

You can also run ~histdb-top~ to see your most frequent commands, and ~histdb-top dir~ to show your favourite directory for running commands in, but these commands are really a bit useless.
** Example:

#+BEGIN_SRC text
$ histdb strace
time   ses  dir  cmd
17/03  438  ~    strace conkeror
22/03  522  ~    strace apropos cake
22/03  522  ~    strace -e trace=file s
22/03  522  ~    strace -e trace=file ls
22/03  522  ~    strace -e trace=file cat temp/people.vcf
22/03  522  ~    strace -e trace=file cat temp/gammu.log
22/03  522  ~    run-help strace
24/03  547  ~    man strace
#+END_SRC

These are all the history entries involving ~strace~ in my history.
If there was more than one screenful, I would need to say ~--limit 1000~ or some other large number.
The command does not warn you if you haven't seen all the results.
The ~ses~ column contains a unique session number, so all the ~522~ rows are from the same shell session.

To see all hosts, add ~--host~ /after/ the query terms.
To see a specific host, add ~--host hostname~.
To see all of a specific session say e.g. ~-s 522 --limit 10000~.
** Integration with ~zsh-autosuggestions~

If you use [[https://github.com/zsh-users/zsh-autosuggestions][zsh-autosuggestions]] you can configure it to search the history database instead of the ZSH history file thus:

#+BEGIN_SRC sh
  _zsh_autosuggest_strategy_histdb_top_here() {
      local query="select commands.argv from
  history left join commands on history.command_id = commands.rowid
  left join places on history.place_id = places.rowid
  where places.dir LIKE '$(sql_escape $PWD)%'
  and commands.argv LIKE '$(sql_escape $1)%'
  group by commands.argv order by count(*) desc limit 1"
      _histdb_query "$query"
  }

  ZSH_AUTOSUGGEST_STRATEGY=histdb_top_here
#+END_SRC

This query will find the most frequently issued command that is issued in the current directory or any subdirectory. You can get other behaviours by changing the query, for example

#+BEGIN_SRC sh
  _zsh_autosuggest_strategy_histdb_top() {
      local query="select commands.argv from
  history left join commands on history.command_id = commands.rowid
  left join places on history.place_id = places.rowid
  where commands.argv LIKE '$(sql_escape $1)%'
  group by commands.argv
  order by places.dir != '$(sql_escape $PWD)', count(*) desc limit 1"
      _histdb_query "$query"
  }
#+END_SRC

This will find the most frequently issued command issued exactly in this directory, or if there are no matches it will find the most frequently issued command in any directory. You could use other fields like the hostname to restrict to suggestions on this host, etc.
* Database schema
The database lives by default in ~$HOME/.histdb/zsh-history.db~.
You can look in it easily by running ~_histdb_query~, as this actually just fires up sqlite with the database.

For inspiration you can also use ~histdb~ with the ~-d~ argument and it will print the SQL it's running.
* Synchronising history
You should be able to synchronise the history using ~git~; a 3-way merge driver is supplied in ~histdb-merge~.

The 3-way merge will only work properly if all the computers on which you use the repository have different hostnames.

The ~histdb-sync~ function will initialize git in the histdb directory and configure the merge driver for you first time you run it.
Subsequent times it will commit all changes, pull all changes, force a merge, and push all changes back again.
The commit message is useless, so if you find that kind of thing upsetting you will need to fix it.

The reason for using ~histdb-sync~ instead of doing it by hand is that if you are running the git steps in your shell the history database will be changed each command, and so you will never be able to do a pull / merge.
* Completion
None, and I've used the names with underscores to mean something else.
* Pull requests / missing features
Happy to look at changes.
I did at one point have a reverse-isearch thing in here for searching the database interactively, but it didn't really make my life any better so I deleted it.