Complete BASH shell environment comparison tool

env-diff [options] [--] CMD

Produce a complete summary of what `CMD` has changed in the environment.

env-diff-save DIRECTORY

Create a directory DIRECTORY containing all the information about the current
shell environment.

env-diff-compare [options] BEFORE AFTER

Compare directories created with env-diff-save.

env-diff-gencode [options] BEFORE AFTER

Generate BASH code to go from BEFORE to AFTER

env-diff-load [options] DIRECTORY

Load the environment from DIRECTORY created with env-diff-save

Run CMD --help to see the manpage for each command

All commands save and compare these aspects of the shell environment:

• Environment variables
• Shell variables
• Associative arrays
• Normal arrays
• Shell options (shopt and set)
• Functions
• Traps

CMD can be any command although running executables will have no effect on the environment so it will be either source command or a call to a shell function but it can also be plain shell code.

Installing

Clone this repository and source env-diff-cmd.bash from the repo in your ~/.bashrc.

You can also copy the dot-config-env-diff.yml to $HOME/.config/env-diff.yml or make your own using the file as a template.

Usage

Basic usage

Sourcing env-diff-cmd.bash defines the env-diff() shell function which can receive any BASH code as an argument (calling a shell function, defining variables or other stuff, sourcing a script)

env-diff 'f(){ echo "HELLO" ; }
    PATH=new-thing/bin:${PATH}
    A=B
    set -o pipefail
    shopt -s extdebug
    g(){ echo "This is new g" ; }
    unset HOSTNAME
    export -n USER'

Saving environments to compare

This will show the same output as above but may be more convenient to compare environments from different shells.

env-diff-save INITIAL

# Change things about our shell environment
f(){ echo "HELLO" ; }
PATH=new-thing/bin:${PATH}
A=B
set -o pipefail
shopt -s extdebug
g(){ echo "This is new g" ; }
unset HOSTNAME
export -n USER

env-diff-save FINAL

env-diff-compare INITIAL FINAL

Loading a saved environment

The command env-diff-gencode INITIAL FINAL will procuce shell code to go from INITIAL to FINAL:

env-diff-save INITIAL

# Change things about our shell environment
f(){ echo "HELLO" ; }
PATH=new-thing/bin:${PATH}
A=B
set -o pipefail
shopt -s extdebug
g(){ echo "This is new g" ; }
unset HOSTNAME
export -n USER

env-diff-save FINAL

env-diff-gencode INITIAL FINAL > to_source

Now in a new shell, we can do

source to_source
env-diff-save NEW_FINAL
env-diff-compare FINAL NEW_FINAL

and see that sourcing the file made our environment NEW_FINAL identical to the FINAL we had created earlier.

Convenience function

The env-diff-load TO_LOAD command is a convenience function that combines the steps above to generate and evaluate code to go from the current shell environment to the one saved in TO_LOAD. It is roughly equivalent to

env-diff-load(){
    env-diff-save current
    eval "$(env-diff-gencode current $1)"
}

Details

• env-diff manpage
• env-diff-save manpage
• env-diff-gencode manpage
• env-diff-load manpage

Dependencies

• jq
• standard UNIX tools (sort, comm, cut, cat, mkdir, mktemp)
• python3
  • pyyaml is optional but required to read config files
  • pygments is optional. If it is present it will be used to color function bodies.
  • shlib is required to use env-diff-gencode and env-diff-load to quote values of shell variables.
• For the autocomplete, a recent enough version of bash-completion