Clean up legacy configurations and outdated settings

[xtetsuji]

Problem

The dotfiles repository contains various legacy configurations that were added over many years. Some of these settings are no longer relevant in modern environments and should be cleaned up to improve maintainability and reduce complexity.

Identified Legacy Settings

🗑️ Clear candidates for removal

CVS-related (2000s era)

• common_env: export CVS_RSH=ssh - CVS is rarely used today
• cvsrc file - CVS configuration file
• gitignore: .cvspass entry - CVS password file

EUC-JP encoding legacy

• screenrc.euc-jp file - UTF-8 is now standard
• inputrc: #set kanji-code euc commented legacy settings
• gitconfig: eucjpdiff, eucjpdf aliases - EUC-JP specific git commands

SSH-Agent manual management

• common_env lines 190-200: ssh-agent setup
• Modern OS handles ssh-agent automatically
• Originally added for GNU Screen session sharing

🤔 Requires evaluation

GNU Screen support

• bash_aliases: __cdhook_screen_title_pwd function
• bashrc, zshrc: screen-specific prompt settings
• screenrc, screenrc.euc-jp files
• Decision needed: Remove if fully migrated to tmux

Legacy tools

• common_env: LV='-c -Ouj' - lv pager (less is now standard)
• bash_aliases: alias lv='lv -c'
• Decision needed: Remove if no longer used

Legacy system support

• inputrc: convert-meta, meta-flag related comments
• xsession file - X11 desktop environment
• Decision needed: Keep if still using X11 environments

Proposed Approach

1. Phase 1: Safe removals - Remove clearly obsolete items

   • CVS-related configurations
   • EUC-JP encoding settings
   • SSH-agent manual management

2. Phase 2: Conditional removals - Evaluate usage and decide

   • Screen vs tmux migration status
   • Legacy tool usage assessment
   • Environment compatibility requirements

3. Phase 3: Documentation - Document decisions for future reference

Implementation Strategy

• Work incrementally, testing after each change
• Document reasoning for each removal decision
• Keep git history for easy rollback if needed
• Consider creating a legacy branch before major cleanups

Benefits

• Reduced complexity and maintenance burden
• Faster shell startup times
• Clearer configuration purpose
• Better focus on modern tooling

Notes

This cleanup should be done thoughtfully, considering:

• Current usage patterns
• Multi-environment compatibility needs
• Historical value vs maintenance cost
• Rollback possibilities