問題: 如何找到 LC_CTYPE 這個環境變量在哪兒定義的？
可以按照下面順序檢查
Some places to look first:
System wide
/etc/environment: specifically meant for environment variables
/etc/env.d/*: environment variables, split in multiple files
/etc/profile: all types of initialization scripts
/etc/profile.d/*: initialization scripts
/etc/bashrc, /etc/bash.bashrc: meant for functions and aliases
User specific
~/.bash_profile: initialization for login (bash-)shells
~/.bashrc: initialization for all interactive (bash-)shells
~/.profile: used for all shells
~/.cshrc, ~/.zshrc, ~/.tcshrc: similar for non-bash shells