Bash - Restrict Interactive-Only Commands

The problem

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If your Claude Code (or other AI coding agent) keeps getting errors like these when running bash commands:

stty: stdin isn't a terminal
bind: warning: line editing not enabled

It’s because your shell profile contains commands that only work in interactive shells.

The fix

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Guard interactive-only commands with [[ $- == *i* ]]:

# One-liners
[[ $- == *i* ]] && stty -ixon
[[ $- == *i* ]] && bind '"\C-s": forward-search-history'

# Multiple commands
if [[ $- == *i* ]]; then
    stty -ixon
    bind '"\C-s": forward-search-history'
    bind '"\C-r": reverse-search-history'
fi

The $- variable contains current shell options. If it includes i, the shell is interactive. This is better than checking for specific tool environment variables - it works for any non-interactive invocation (scripts, cron, CI/CD).

Why does this happen?

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~/.bashrc vs ~/.bash_profile

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• ~/.bash_profile runs for login shells - one-time setup like PATH and environment variables
• ~/.bashrc runs for interactive non-login shells - aliases, prompt, functions

Best practice is to source ~/.bashrc from ~/.bash_profile and put everything in ~/.bashrc:

# ~/.bash_profile
if [ -f "$HOME/.bashrc" ]; then
    source "$HOME/.bashrc"
fi

macOS specifics

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On macOS, Terminal.app and iTerm2 open login shells by default, so they run ~/.bash_profile. This is opposite to most Linux terminals which run ~/.bashrc. That’s why many macOS users put everything in ~/.bash_profile - it works for them, but breaks non-interactive tools.

Why Claude Code sources your profile

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Claude Code starts its shell as a login shell (-l flag) to get access to your $PATH, environment variables, and tools like nvm, pyenv, cargo, etc. This means it sources ~/.bash_profile (and ~/.bashrc if sourced from it). But unlike Terminal.app, Claude Code’s shell is non-interactive - so stty, bind, and similar commands fail.