为何树莓派PostScript RIP打印服务器配置脚本生效异常？

问题描述 #

尝试将树莓派配置为PostScript RIP打印服务器，执行setup-rip-server.sh脚本后显示成功，但Mac端无法连接IPP服务，提示“无法连接‘ipp’，是否仍要创建打印机？”。

脚本内容 #

#!/bin/bash
# setup-rip-server.sh — Configure Raspberry Pi as a PostScript RIP print server
# Usage: sudo ./setup-rip-server.sh [-v]

set -e

# Check for root privileges
if [ "$EUID" -ne 0 ]; then
    echo "This script must be run as root."
    echo "Please re-run it using: sudo ./setup-rip-server.sh"
    exit 1
fi

# Verbose mode flag
VERBOSE=false
if [ "$1" == "-v" ]; then
    VERBOSE=true
fi

# Output control
quiet() {
    if $VERBOSE; then
        "$@"
    else
        "$@" &>/dev/null
    fi
}

REQUIRED_PACKAGES=(cups cups-bsd ghostscript cron)

echo "Checking required packages..."
for pkg in "${REQUIRED_PACKAGES[@]}"; do
    if dpkg -s "$pkg" &>/dev/null; then
        echo "$pkg is already installed."
    else
        echo "Installing $pkg..."
        quiet apt update
        quiet apt install -y "$pkg"
    fi
done

echo "Checking CUPS service status..."
if systemctl is-enabled cups &>/dev/null; then
    echo "CUPS is already enabled."
else
    echo "Enabling CUPS..."
    quiet systemctl enable cups
fi

if systemctl is-active cups &>/dev/null; then
    echo "CUPS is already running."
else
    echo "Starting CUPS..."
    quiet systemctl start cups
fi

echo "Configuring CUPS for remote access..."
CUPSD_CONF="/etc/cups/cupsd.conf"
cp "$CUPSD_CONF" "$CUPSD_CONF.bak"

sed -i 's/^Listen localhost:631$/Port 631/' "$CUPSD_CONF"
sed -i '/^<Location \/>/,/^<\/Location>/ s/Require local/Allow all/' "$CUPSD_CONF"
sed -i '/^<Location \/admin>/, /^<\/Location>/ s/Require local/Allow all/' "$CUPSD_CONF"
sed -i '/^<Location \/admin\/conf>/, /^<\/Location>/ s/Require local/Allow all/' "$CUPSD_CONF"

echo "Restarting CUPS with updated configuration..."
quiet systemctl restart cups

echo "Discovering available printers..."
PRINTERS=($(lpstat -p | awk '{print $2}'))

if [ ${#PRINTERS[@]} -eq 0 ]; then
    echo "No printers found. Please add a printer via http://<raspberrypi.local>:631"
    exit 1
fi

echo "Available printers:"
for i in "${!PRINTERS[@]}"; do
    echo "$((i+1)). ${PRINTERS[$i]}"
done

read -p "Enter the number of the printer to set as default: " SELECTION

if ! [[ "$SELECTION" =~ ^[0-9]+$ ]] || [ "$SELECTION" -lt 1 ] || [ "$SELECTION" -gt "${#PRINTERS[@]}" ]; then
    echo "Invalid selection. No changes made."
    exit 1
fi

DEFAULT_PRINTER="${PRINTERS[$((SELECTION-1))]}"
quiet lpoptions -d "$DEFAULT_PRINTER"
echo "Default printer set to: $DEFAULT_PRINTER"

PURGE_SCRIPT="/usr/local/bin/purge-cups-queue.sh"
echo "Installing nightly queue purge script at $PURGE_SCRIPT..."

cat <<EOF > "$PURGE_SCRIPT"
#!/bin/bash
# purge-cups-queue.sh — Clears all CUPS print queues nightly

cancel -a
echo "$(date): CUPS print queue purged." >> /var/log/cups-purge.log
EOF

chmod +x "$PURGE_SCRIPT"

echo "Scheduling daily purge via cron..."
CRON_ENTRY="0 0 * * * $PURGE_SCRIPT"
(crontab -l 2>/dev/null | grep -F "$PURGE_SCRIPT") || (crontab -l 2>/dev/null; echo "$CRON_ENTRY") | crontab -

echo "RIP print server setup complete."
echo "Clients can now send PostScript jobs via IPP to this Raspberry Pi."
echo "Print queue will be automatically purged nightly at midnight."

当前cupsd.conf配置 #

LogLevel warn
MaxLogSize 0
# Allow remote access
Port 631
Listen /var/run/cups/cups.sock
Listen 0.0.0.0:631
Browsing On
BrowseLocalProtocols dnssd
DefaultAuthType Basic
WebInterface Yes
<Location />
  # Allow remote access...
  Order allow,deny
  Allow all
</Location>
<Location /admin>
</Location>
<Location /admin/conf>
  AuthType Default
  Require user @SYSTEM
</Location>
<Policy default>
  JobPrivateAccess default
  JobPrivateValues default
  SubscriptionPrivateAccess default
  SubscriptionPrivateValues default
  <Limit Create-Job Print-Job Print-URI Validate-Job>
    Order deny,allow
  </Limit>
  <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>
    Require user @OWNER @SYSTEM
    Order deny,allow
  </Limit>
  <Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Get-Devices>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
  </Limit>
  <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs CUPS-Reject-Jobs>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
  </Limit>
  <Limit Cancel-Job CUPS-Authenticate-Job>
    Require user @OWNER @SYSTEM
    Order deny,allow
  </Limit>
  <Limit All>
    Order deny,allow
  </Limit>
</Policy>
<Policy authenticated>
  JobPrivateAccess default
  JobPrivateValues default
  SubscriptionPrivateAccess default
  SubscriptionPrivateValues default
  <Limit Create-Job Print-Job Print-URI Validate-Job>
    AuthType Default
    Order deny,allow
  </Limit>
  <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>
    AuthType Default
    Require user @OWNER @SYSTEM
    Order deny,allow
  </Limit>
  <Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
  </Limit>
  <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs CUPS-Reject-Jobs>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
  </Limit>
  <Limit Cancel-Job CUPS-Authenticate-Job>
    AuthType Default
    Require user @OWNER @SYSTEM
    Order deny,allow
  </Limit>
  <Limit All>
    Order deny,allow
  </Limit>
</Policy>

排查与修复步骤 #

1. 验证网络连通性 #

• 在Mac上执行ping raspberrypi.local，确认能正常连通；如果不通，安装树莓派Bonjour服务：sudo apt install avahi-daemon，安装完成后重启服务sudo systemctl restart avahi-daemon。
• 在Mac上执行nc -zv raspberrypi.local 631，确认631端口可访问；如果连接失败，临时关闭树莓派防火墙测试：sudo iptables -F，测试通过后永久开放端口：sudo ufw allow 631（若使用ufw防火墙）。

2. 修正CUPS配置文件 #

从当前配置看，<Location /admin>块缺失关键配置，按以下方式修改：

• 编辑/etc/cups/cupsd.conf，更新<Location /admin>块：

<Location /admin>
  Order allow,deny
  Allow all
  AuthType Default
  Require user @SYSTEM
</Location>

• 确保普通打印权限允许远程访问，在<Policy default>的<Limit Create-Job Print-Job Print-URI Validate-Job>块内添加允许规则：

<Limit Create-Job Print-Job Print-URI Validate-Job>
  Order deny,allow
  Allow all
</Limit>

• 重启CUPS服务：sudo systemctl restart cups

3. 确认IPP路径正确性 #

Mac端添加打印机时，需使用完整IPP路径，格式为：
ipp://raspberrypi.local:631/printers/<你的打印机名称>
可通过访问树莓派CUPS管理页面http://raspberrypi.local:631/printers查看打印机的准确路径。

4. Mac端配置调整 #

• 手动添加打印机：打开系统设置-打印机与扫描仪，点击+号，选择IP标签，协议选Internet Printing Protocol (IPP)，地址填raspberrypi.local，端口631，队列填printers/<打印机名称>，选择对应PostScript驱动完成添加。
• 清除Mac打印缓存：执行sudo rm -rf /Library/Printers/，重启Mac后重新添加打印机。

5. 查看CUPS日志定位问题 #

在树莓派上实时查看CUPS错误日志：tail -f /var/log/cups/error_log，同时在Mac端尝试连接，根据日志中的错误信息（如权限拒绝、路径不存在等）精准排查问题。

内容的提问来源于stack exchange，提问作者headbanger