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Saving Command Line History

I’ve never been satisfied with the defaults for the way linux & osx save command line history. For all practical purposes, when we’re talking about text files, we have infinite hard drive space. Why not save every command that we ever type.

First, A Roundup of What’s Out There

Here’s the baseline of what I started with, in bash:

declare -x HISTFILESIZE=1000000000
declare -x HISTSIZE=1000000

But there are a few problems with this: bash and zsh sometimes corrupt their history files, and multiple terminals sometimes don’t interact properly. A few pages have suggested hacks to PROMPT_COMMAND to get terminals to play well together:

  • relatedly, shopt -s histappend (for bashrc)
  • export PROMPT_COMMAND=”history -n; history -a” (upon every bash prompt write out to history and read in latest history). While this works, it feels a bit hacky has a more formalized version of the above.

Further down the rabbit-hole, this guy has a quite complicated script to output each session’s history to a uniquely ID’d .bash_history file. Good, but it only exports upon exit from a session (which I rarely do… for me, sessions either crash (which doesn’t trigger the write) or I don’t close them… still, it’s an interesting idea).

(Aside: shell-shink was an interesting solution to this issue, though it had its own set of problems — privacy implications… in case I type passwords in the command-prompt, I would really rather not have this stuff live on the web. Also, it’s now obselete and taken down, so it’s not even an alternative now). Links, for posterity:
[1] [2] [3]

Now, what I finally decided to use

Talking to some folks at work, I found this wonderful hack: modify $PROMPT_COMMAND to output to a history file manually… but also output a little context — the timestamp and current path, along with the command. Beautiful!

export PROMPT_COMMAND='if [ "$(id -u)" -ne 0 ]; then echo "`date` `pwd` `history 1`" >> ~/.shell.log; fi'

ZSH doesn’t have $PROMPT_COMMAND but it does have an equivalent.

For posterity, here’s what I ended up with:

  • zsh:

    function precmd() {
    if [ "$(id -u)" -ne 0 ]; then
    echo "`/bin/date +%Y%m%d.%H%M.%S` `pwd` `history -1`" >> ${FULL_CMD_LOG};

  • bash:

    case "$TERM" in
    DISP='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD/$HOME/~}\007"'
    SAVEBASH='if [ "$(id -u)" -ne 0 ]; then echo "`/home/mote/bin/ndate` `pwd` `history 1`" >> ${BASHLOG}; fi'

This gets ya a wonderful logfile, full of context, with no risk of corruption:

20110306.1819.03 /home/mote/dev/load 515 ls
20110306.1819.09 /home/mote/dev/load 516 gvim
20110306.1819.32 /home/mote/dev/load 517 svn st
20110306.1819.35 /home/mote/dev/load 518 svn add
20110306.1819.49 /home/mote/dev/load 519 svn ci -m “script to log if screensaver is running”

(As an aside, you’ll notice that these commands are all timestamped. Imagine the wealth of personal infometrics data that we can mine from here! When am I most productive (as measured by command-density-per-time-of-day?). What really are my working hours? When do I wake? Sleep? Lunch? )

Next up, need to make a `history`-like command to tail more copy-pastable stuff out of this file.

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