通过SSH登录后显示可升级的软件包

如果你想SSH登录路由器后能够直观的显示当前有哪些软件包可以升级，可以通过下面两个步骤实现：

1. 建立一个用户配置文件脚本在软件包列表中检查哪些软件包可以升级
2. 在crontab中定期执行“opkg update”来更新软件包列表,

或者简单的将这些集成在用户配置文件脚本中，每次登陆时上述工作自动完成。

当运行正常时，每次通过SSH登录时你会看到如下界面显示：

BusyBox v1.25.1 () built-in shell (ash)

     _________
    /        /\      _    ___ ___  ___
   /  LE    /  \    | |  | __|   \| __|
  /    DE  /    \   | |__| _|| |) | _|
 /________/  LE  \  |____|___|___/|___|                      lede-project.org
 \        \   DE /
  \    LE  \    /  -----------------------------------------------------------
   \  DE    \  /    Reboot (17.01.1, r3316-7eb58cf109)
    \________\/    -----------------------------------------------------------

151 packages are installed.
4 packages can be upgraded.

root@LEDE:~#

也可以在一个命令中选择升级其中部分或全部软件包。

为了创建用户配置文件脚本，首先用root用户登录SSH。在这个例子中我们使用了nano作为文本编辑器（nano比系统默认的文本编辑器vim使用要简单一些），当然你可以根据自己的喜好选择文本编辑器。

nano ~/.profile

#!/bin/sh

opkgInstalled="$(opkg list-installed 2> /dev/null | wc -l)" #silencing error output
opkgUpgradable="$(opkg list-upgradable 2> /dev/null | wc -l)" #silencing error output

echo "$opkgInstalled packages are installed." && echo "$opkgUpgradable packages can be upgraded." && echo

要使上述脚本正常工作，软件包列表要在登录时可用且保持最新。自动更新软件包列表可以以下三种途径：

1. 固定时间间隔 → crontab
2. 在每次启动时 → 启动脚本
3. 每次登录时on login → 同样使用用户配置文件脚本

Keep in mind that this will occupy precious RAM space on low memory devices (16+32MB). See the third method for a low-ram-friendly script.

Schedule crontab to “opkg update” once per week, either via LuCI or via commandline.

• via LuCI: Add below lines via LuCi > System > Scheduled Tasks
• via command line: crontab -e → add below lines

1 0 * * 0 /bin/opkg update # Update list of available packages every Sunday 00:01
# crontab and fstab must end with the last line a space or comment

You can change the interval as you like, but keep in mind that every interval below 24h is a waste of resources, since release packages do not get compiled that often.

This method only works if you frequently reboot your hardware. Keep in mind that this will occupy precious RAM space on low memory devices (16+32MB). See the third method for a low-ram-friendly script.

If you prefer to run “opkg list” only once at startup, rather than in regular intervals as shown above, you can do so by means of the startup script rc.local.

• via LuCI: Add below lines via LuCi > System > Startup > Local Startup
• via commandline: edit etc/rc.local and add below lines

/bin/opkg update # Update list of available packages
exit 0

Now everytime you login with Dropbear (SSH) you will see the number of total packages installed and how many packages can be upgraded.

You can place the updating commands in the same profile file, as that script is executed each time the user logs in with ssh or serial console.

The main drawback is that the user will have to wait a few seconds for the update to finish before he can start writing commands, which if all goes well is just a few seconds. It will be quite a bit more if there is no internet access, as opkg will take a while to figure out that there is no internet connection. So a check for internet connectivity is included. If no internet is detected the update is skipped.
For the sake of being low-RAM friendly, there is a check that deletes automatically the package lists if the device has less then 32 MiB of free RAM.

This is the whole .profile script:

nano ~/.profile

#!/bin/sh

if wget -q --spider https://lede-project.org/start; then  # if LEDE website/wiki is available we update
  echo "You are connected to the internet. Checking for updates, please wait..." && echo
  opkg update > /dev/null 2>&1 #silenced standard output and error output

  opkgInstalled="$(opkg list-installed 2> /dev/null | wc -l)" #silencing error output
  opkgUpgradable="$(opkg list-upgradable 2> /dev/null | wc -l)" #silencing error output

  echo "$opkgInstalled packages are installed." && echo "$opkgUpgradable packages can be upgraded." && echo
  
  memLimit=32000 # in bytes
  if [ "$(grep MemFree /proc/meminfo | awk '{print$2}')" -lt $memLimit ]; then
    for opkg_package_lists in /var/opkg-lists/*
    do
      if [ -f "$opkg_package_lists" ]; then #prevent error if opkg update fails
        rm -r /var/opkg-lists/*
        echo "Warning: Memory limit $memLimit bytes. Removed downloaded package lists to save memory."
        echo #only remove when free RAM is less than set memory limit (default 32 MiB)
      fi
    done
  fi
  else
  echo "You are not connected to the internet. Unable to check for updates." && echo
fi

By default, firmware upgrade procedure does not back up /root/.profile so we need to add it to the list of custom files to back up.

echo  '/root/.profile #my profile with update script '  >> /etc/sysupgrade.conf

Other files created or modified by this tutorial (chrontabs and /etc/rc.local) are already in the whitelist of files preserved.

For more information, please check the Upgrading LEDE from the Command Line

'opkg upgrade package_name' allow upgrading one package.

To upgrade all packages, follow check_for_any_upgradable_packages.

Please be warned that package upgrades are processed without order. Please make sure to have sufficient space on your device.

Automating OpenWrt package upgrades is strongly discouraged, unless you manage a central repository and push upgrades from there.

If you have a better way of doing this, please update this user guide. You can also add the above script to “/etc/profile” which is the system default, but you are better off keeping that untouched as to prevent issues.

Enjoy!