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Safe Source Library

The safe_source.lib.sh library provides a robust and reusable mechanism to temporarily source Bash scripts and fully revert any changes made to the shell environment. This includes environment variables, functions, aliases, and exported variables.

Features

  • Full Environment Snapshot: Captures variables, functions, aliases, and exports before sourcing.
  • Safe Sourcing and Reversion: All changes are isolated and reversible.
  • Nested Support: Multiple scripts can be sourced and unsourced independently (stack-based).
  • Minimal Side Effects: Reverts exactly what changed—nothing more, nothing less.
  • Reusable as a Library: Designed to be included in any Bash script.

Usage

1. Include the Library

source /path/to/safe_source.lib.sh

2. safe_source <script_path>

Safely source another script, taking a snapshot of your current shell environment.

safe_source ./config.sh

3. safe_unsource

Revert changes made by the last script sourced using safe_source.

safe_unsource

Example

Subscripts

a.sh:

export VAR_A="from A"
alias hello_a='echo Hello from A'
function greet_a() { echo "Greet from A"; }

b.sh:

export VAR_B="from B"
alias hello_b='echo Hello from B'
function greet_b() { echo "Greet from B"; }

Main Script

#!/usr/bin/env bash
source ./safe_source.lib.sh

safe_source ./a.sh
safe_source ./b.sh

echo "${VAR_A}"
echo "${VAR_B}"
hello_a
hello_b
greet_a
greet_b

safe_unsource  # removes b.sh effects
safe_unsource  # removes a.sh effects

Behavior

  • After sourcing a.sh and b.sh, all functions, aliases, and variables are available.
  • After calling safe_unsource twice, none of the sourced script elements remain.

Error Handling

  • Invalid paths produce:

    Error: Script './missing.sh' does not exist.

  • Calling safe_unsource with no stack:

    Error: No environment snapshot to unsource.

Notes

  • Temporary Files:
    • Used in /tmp to snapshot the environment. Auto-cleaned during unsourcing.
  • Safe to Source Multiple Times:
    • Guards prevent reloading and redefining the library or functions.
  • Fallback Logging:
    • If info, error, warn, etc. are not defined, they’re created as basic echo-style functions.

License

This script is provided under the MIT License. Feel free to use and modify it for your needs.

Happy Sourcing! 🚀