enhanced .bashrc

bashrc-enhancer.sh

#!/usr/bin/env bash
set -euo pipefail

BASHRC="${HOME}/.bashrc"
BASH_ALIASES="${HOME}/.bash_aliases"
PROFILE="${HOME}/.profile"
LSC_DIR="${HOME}/.lscolors"
LSC_SCRIPT="${LSC_DIR}/lscolors.sh"
LSC_URL="https://raw.githubusercontent.com/ahmadassaf/dircolors/refs/heads/master/lscolors.sh"

# 0) Require ~/.bashrc to exist
if [ ! -f "$BASHRC" ]; then
  echo "Error: ${BASHRC} does not exist. Aborting." >&2
  exit 1
fi

# 1) Ensure alias l="ls -al" exactly once
alias_present=false

# Check current shell
if alias l >/dev/null 2>&1; then
  alias_present=true
fi

# Check .bashrc, .bash_aliases, .profile
for f in "$BASHRC" "$BASH_ALIASES" "$PROFILE"; do
  if [ -f "$f" ] && grep -Eq '^[[:space:]]*alias[[:space:]]+l=' "$f"; then
    alias_present=true
  fi
done

if $alias_present; then
  echo 'Alias l already present (in shell or config).'
else
  echo 'alias l="ls -al"' >> "$BASHRC"
  echo "Added alias l to ${BASHRC}"
fi

# 2) Ensure ~/.lscolors exists and fetch lscolors.sh if directory missing
if [ ! -d "$LSC_DIR" ]; then
  mkdir -p "$LSC_DIR"
  echo "Created ${LSC_DIR}"

  if command -v curl >/dev/null 2>&1; then
    curl -L -o "$LSC_SCRIPT" "$LSC_URL"
  elif command -v wget >/dev/null 2>&1; then
    wget -O "$LSC_SCRIPT" "$LSC_URL"
  else
    echo "Error: neither curl nor wget is installed. Please install one and re-run." >&2
    exit 1
  fi

  echo "Downloaded lscolors.sh to ${LSC_SCRIPT}"
else
  echo "${LSC_DIR} already exists; skipping download step."
fi

# 3) Ensure sourcing line is present exactly once in ~/.bashrc
SOURCE_LINE='source ~/.lscolors/lscolors.sh'
if ! grep -Fxq "$SOURCE_LINE" "$BASHRC"; then
  echo "$SOURCE_LINE" >> "$BASHRC"
  echo "Added sourcing line to ${BASHRC}"
else
  echo "Sourcing line already present in ${BASHRC}"
fi

# 4) Add optimized prompt block (no chroot info), portable across distros
PROMPT_MARKER_BEGIN="# BEGIN zz custom prompt"
PROMPT_MARKER_END="# END zz custom prompt"

add_custom_prompt() {
  cat >> "$BASHRC" <<'BASHRC_EOF'
# BEGIN zz custom prompt
# Only set PS1 for interactive shells
if [[ $- == *i* ]]; then
  # Show "(screen)" when inside GNU screen
  if [[ -n "$STY" ]]; then
    SCREEN_INDICATOR="(screen)"
  else
    SCREEN_INDICATOR=""
  fi

  # Keep hostname dynamic via hostname -f
  PROMPT_HOST=$(hostname -f)

  # Prompt:
  # - \u user, \w cwd, \$ root/# vs user/$
  # - Colors wrapped in \[ \] to keep readline happy
  PS1="\[\e[1;31m\]\u\[\e[1;33m\]@\[\e[1;36m\]${PROMPT_HOST} \[\e[1;33m\]\w \[\e[1;35m\]${SCREEN_INDICATOR} \$ \[\e[0m\]"
fi
# END zz custom prompt
BASHRC_EOF
}

# Detect PS1 lines (at line start, allowing leading spaces)
ps1_lines=$(grep -nE '^[[:space:]]*PS1=' "$BASHRC" || true)

if [ -z "$ps1_lines" ]; then
  # No PS1 found — add our custom prompt
  add_custom_prompt
  echo "Added custom prompt to ${BASHRC}"
else
  # Check whether any existing PS1 already looks like our custom one
  if grep -Eq '^[[:space:]]*PS1=.*PROMPT_HOST.*SCREEN_INDICATOR' "$BASHRC"; then
    echo "Existing PS1 appears to be the custom prompt already; leaving it as-is."
  else
    echo "A PS1 line exists in ${BASHRC}, and it is not the custom one."
    reply=""
    if ! read -rp "Replace existing PS1 with the custom prompt? [y/N] " reply </dev/tty; then
      reply="n"
    fi
    case "${reply:-n}" in
      [yY][eE][sS]|[yY])
        # Comment out all leading PS1= lines (backup created)
        sed -i.bak '/^[[:space:]]*PS1=/ s/^/# disabled by bashrc-enhancer: /' "$BASHRC"
        add_custom_prompt
        echo "Replaced existing PS1 with custom prompt. Backup saved as ${BASHRC}.bak"
        ;;
      *)
        echo "Keeping existing PS1. No custom prompt added."
        ;;
    esac
  fi
fi