Shell History

Inspired by bamos/zsh-history-analysis.

Visualize your usage of Bash/Zsh through a web app thanks to Flask and Highcharts!

Duration	Length	Type
Exit code	Hourly	Daily
Over time	Markov chain	Top commands

Post your charts ideas in this issue!

• Requirements
• Installation
• Setup
• Usage
• Some technical info
  • How it works
  • History file format
  • How we get the values
• License

Requirements

Shell History requires Python 3.6 or above.

Installation

With pip:

python3.6 -m pip install shellhistory

With pipx:

python3.6 -m pip install --user pipx

pipx install --python python3.6 shellhistory

Setup

shellhistory needs a lot of info to be able to display various charts. The basic shell history is not enough. In order to generate the necessary information, you have to enable the shell extension.

At shell startup, in .bashrc or .zshrc, put the following:

# only load it for interactive shells
if [[ $- == *i* ]] && command -v shellhistory-location &>/dev/null; then
    . $(shellhistory-location)
    shellhistory enable
fi

... and now use your shell normally!

If you want to stop shellhistory, simply run shellhistory disable.

Note: for performance reasons, you can also use the static, absolute path to the source file. Indeed, calling shellhistory-location spawns a Python process which can slow down your shell startup. Get the path once with shellhistory-location, and use . <ABS_PATH>. In my case it's . ~/.local/pipx/venvs/shellhistory/lib/python3.6/site-packages/shellhistory/shellhistory.sh.

Usage

Launch the web app with shellhistory-web. Now go to http://localhost:5000/ and enjoy!

You will need Internet connection since assets are not bundled.

Some technical info

How it works

When you enter a command, shellhistory will compute values before and after the command execution. In Bash, it uses a trap on DEBUG and the PROMPT_COMMAND variable (man bash for more information). For Zsh, it uses the preexec_functions and precmd_functions arrays (anyone knows where to find the official documentation for these? Some information in man zshmisc).

Before the command is executed, we start a timer, compute the command type, and store the current working directory and the command itself.

After the command has finished, we store the return code, and stop the timer.

History file format

Fields saved along commands are start and stop timestamps, hostname, username, uuid (generated), tty, process' parents, shell, shell level, command type, return code, and working directory (path), in the following format: :start:stop:uuid:parents:host:user:tty:path:shell:level:type:code:command.

• multi-line commands are prepended with a semi-colon ; instead of a colon :, starting at second line
• start and stop timestamps are in microseconds since epoch
• process' parents and working directory are encoded in base64 to avoid delimiter corruption.

Example (multi-line command):

:1510588139930150:1510588139936608:40701d9b-1807-4a3e-994b-dde68692aa14:L2Jpbi9iYXNoCi91c3IvYmluL3B5dGhvbiAvdXNyL2Jpbi94LXRlcm1pbmFsLWVtdWxhdG9yCi91c3IvYmluL29wZW5ib3ggLS1zdGFydHVwIC91c3IvbGliL3g4Nl82NC1saW51eC1nbnUvb3BlbmJveC1hdXRvc3RhcnQgT1BFTkJPWApsaWdodGRtIC0tc2Vzc2lvbi1jaGlsZCAxMiAyMQovdXNyL3NiaW4vbGlnaHRkbQovc2Jpbi9pbml0Cg==:myhost:pawamoy:/dev/pts/1:L21lZGlhL3Bhd2Ftb3kvRGF0YS9naXQvc2hlbGxoaXN0Cg==:/bin/bash:1:builtin:0:echo "a
;b
;c" | wc -c

Note: later we could use CSV formatting, quoting strings and doubling double-quotes in those if any. It would make the file more readable for humans, and easily importable in other programs. See issue 26.

The previous example would look like this:

1510588139930150,1510588139936608,40701d9b-1807-4a3e-994b-dde68692aa14,"/bin/bash
/usr/bin/python /usr/bin/x-terminal-emulator
/usr/bin/openbox --startup /usr/lib/x86_64-linux-gnu/openbox-autostart OPENBOX
lightdm --session-child 12 21
/usr/sbin/lightdm
/sbin/init",myhost,pawamoy,/dev/pts/1,"/media/pawamoy/Data/git/shellhist",/bin/bash,1,builtin,0,"echo ""a
b
c"" | wc -c"

How we get the values

Start and stop time are obtained with date '+%s%N', return code is passed directly with $?, working directory is obtained with $PWD and command type with type for Bash and whence for Zsh.

Values for UUID, parents, hostname, and TTY are computed only once, when shellhistory.sh is sourced. Indeed they do not change during usage of the current shell process. Hostname and TTY are obtained through commands hostname and tty. UUID is generated with command uuidgen. Also note that UUID is exported in subshells so we know which shell is a subprocess of another, and so we are able to group shell processes by "sessions", a session being an opened terminal (be it a tab, window, pane or else). Parents are obtained with a function that iteratively greps ps result with PIDs (see shellhistory.sh).

Values for user, shell, and level are simply obtained through environment variables: $USER, $SHELL (though its use here is incorrect: see issue 24), and $SHLVL (also see issue 25).

The last command is obtained with the command fc. Using fc allows shellhistory to have the same behavior as your history:

• if commands starting with spaces are ignored, they will be ignored in shellhistory as well.
• same for duplicates (entering ls two or more times saves only the first instance). Note however that if you type the same command as the previous one in an other terminal, it will still be appended, unless you manage to synchronize your history between terminals, which is another story.

Additionally, if you enter an empty line, or hit Control-C before enter, nothing will be appended either. The trick behind this is to check the command number in the current history (see shellhistory.sh for technical details).