Bash-Lib Bug Report: Unbound Variable Error During Module Import

[openbiocure]

Summary

Bash-lib fails with "unbound variable" error when importing modules due to improper handling of indirect variable expansion in the import system.

Bug Details

Error Message

/opt/bash-lib/lib/init.sh: line 87: !signal: unbound variable

Affected Version

• Repository: https://github.com/openbiocure/bash-lib
• Branch: main
• Installation method: Official install script

Steps to Reproduce

1. Install bash-lib using the official installation script:

   curl -sSL https://raw.githubusercontent.com/openbiocure/bash-lib/main/scripts/install.sh | bash

2. Create a script that imports multiple modules:

   #!/bin/bash
   set -euo pipefail
   
   source /opt/bash-lib/lib/init.sh
   
   import console
   import http  # This line triggers the error

3. Run the script with strict error handling enabled.

Root Cause Analysis

The issue occurs in /opt/bash-lib/lib/init.sh around line 87:

local signal="BASH_LIB_IMPORTED_${name//\//_}"
[[ -n "${!signal}" ]] && return 0

Problem: The code uses indirect variable expansion ${!signal} but doesn't handle the case where the signal variable itself might be empty or unset. When set -u (nounset) is enabled, this causes an "unbound variable" error.

Context: The signal variable is constructed by replacing forward slashes with underscores in the module name and prefixing with "BASH_LIB_IMPORTED_". If the module name processing results in an empty string or if there are edge cases in the string manipulation, the signal variable becomes empty.

Impact

• Severity: High - Prevents bash-lib from working in environments with strict error handling
• Affected users: Anyone using bash-lib with set -u or set -euo pipefail
• Workaround required: Users must either disable strict error handling or manually set expected environment variables

Current Workaround

Users can work around this by pre-setting the expected environment variables:

# Before importing modules
export BASH_LIB_IMPORTED_http=""
import http

Suggested Fix

The bash-lib team should modify the import function to handle empty signal variables:

local signal="BASH_LIB_IMPORTED_${name//\//_}"
# Add validation to ensure signal is not empty
[[ -z "$signal" ]] && {
    printf "\e[31mError:\e[0m Invalid module name: %s\n" "$name" >&2
    return 1
}
[[ -n "${!signal:-}" ]] && return 0

Or use parameter expansion to provide a default value:

local signal="BASH_LIB_IMPORTED_${name//\//_}"
[[ -n "${!signal:-}" ]] && return 0

Environment Details

• OS: Linux (Docker container)
• Shell: Bash
• Error handling: set -euo pipefail
• Bash-lib path: /opt/bash-lib

Additional Context

This bug was discovered while integrating bash-lib into a Spark/Hive Docker build process where strict error handling is essential for build reliability. The error occurs consistently when importing the http module after the console module.

Files Affected

• /opt/bash-lib/lib/init.sh - Main initialization file containing the import function

Related Issues

This may also affect other modules that use similar indirect variable expansion patterns throughout the bash-lib codebase.

---

Reported by: Integration team working on Spark/Hive Docker builds
Date: $(date)
Priority: High - Blocks production use with strict error handling