bash_ct

ct (Command Trace) is a Bash command resolution tracer that explains how Bash resolves a command and what the kernel ultimately executes.

It traces the full resolution process—covering aliases, functions, keywords, builtins, and external executables—while exposing shadowed commands, overrides, and filesystem indirection.

ct combines and extends type, which, command -v, and file, providing visibility into Bash resolution order, $PATH shadowing, and kernel execution details.

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What ct shows

• Bash resolution order for aliases, functions, keywords, builtins, and executables

• Shadowed commands and overrides (e.g. aliases or functions hiding binaries)

• Full $PATH scan, including shadowed or unreachable entries

• Clear separation of Bash resolution targets vs kernel execution targets

• Filesystem execution details:

  • Canonical executable paths
  • Symlink chains (including /etc/alternatives)
  • ELF interpreters for binaries
  • Shebangs for scripts

• Optional JSON output for scripting and automation

ct is intended for understanding why a command resolves the way it does—not just what it resolves to.

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Features (Quick Summary)

• Traces Bash command resolution for aliases, functions, keywords, builtins, and executables
• Shows Bash vs kernel execution targets
• Highlights shadowed commands and overrides
• Performs a full $PATH scan, including shadowed or unreachable entries
• Detects builtin state (enabled vs disabled)
• Resolves filesystem details: canonical paths, symlink chains, /etc/alternatives, usr-merged directories, ELF interpreters, shebangs
• Safely auto-extends $PATH to include admin/system directories
• Supports -x / --extend for manual path extension
• Handles edge cases: reserved keywords, special characters
• Produces color-coded, human-readable output
• Optional JSON output for scripting and automation
• Supports tab completion
• Preserves shell environment state
• Compatible with gnu-utils and Bash ≥ 4.4
• Works in both interactive shells and scripts

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JSON Output

JSON output is intended for scripting and inspection.

Notes

• Fields may be added in future versions
• Consumers should not assume strict schema stability across major versions
• null indicates “not applicable”
• Boolean fields are always true or false

PATH Entries

Each PATH entry reports:

• Directory
• State (notfound, file, symlink)
• Symlink target (if applicable)
• Shadowed status
• /usr-merge detection

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Requirements

Core dependencies

• grep, file, cut, head, readlink, readelf, awk

Optional (for color output)

• tput

Bash version

• Bash ≥ 4.4

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Installation

1. Manual Installation

Clone the repository.

# Clone the repository.
git clone https://github.com/JB63134/bash_ct.git /usr/local/bin/bash_ct
Source the main script in your .bashrc or .bash_profile
echo "source /usr/local/bin/bash_ct/.bash_ct" >> ~/.bashrc
Apply changes immediately
source ~/.bashrc

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Usage

ct [options] command

Options

Option	Description
-h, --help	Show usage information
-v, --version	Show version and license
-j, --json	Emit JSON output
-x, --extend	Extend $PATH manually

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Examples

ct ls
ct python
ct -j bash

Invalid paths are rejected:

ct /bin/ls
ct ./script

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Screenshots / Output Preview