如果最新版本不起作用，如何將符號鏈接更改為舊版本

Question

我有一個conf文件產品，它將在啟動時啟動產品應用程序。

應用程序文件夾結構：

home/
    jamnes/
          product/
                 installation/
                             product1.0
                             product2.0
                 symlinktoproduct/
                                run.sh

product.conf文件：

# Product start file
#
# Starts the Product App and respawns when it quits

description     " Product Application"

start on desktop-session-start
stop on runlevel [!2345]

respawn
exec /home/james/product/symlinktoproduct/run.sh

如果用戶升級應用程序，我們將在安裝文件夾中放置新版本並更改symlinktoproduct-> latestversion

問題：

如果最新版本不起作用，我如何指向舊版本產品文件。

外殼我在conf文件中有任何檢查，天氣最新版本是否有效。

有人可以幫我這個忙嗎？

操作系統：Ubuntu

Answer 1

您可以在conf文件中添加一個簽入：

exec ( basedir="/home/jamnes/product"
  current_product="${basedir}/symlinktoproduct"

  function run_product {
    echo "Running product `ls -l ${current_product}`"
    ${current_product}/run.sh
    return $?
  }

  # run the latest product
  run_product || {

      # if run.sh returns non-zero exit code, then run previous product
      echo "ERROR: running product `ls -l ${current_product}`"

      # get name of previous product by listing previous entry from installation directory.
      # Assume alphabetical sort order.
      prev_version=`ls -1 ${basedir}/installation | tail -2 | head -1`
      echo "Rollback too previous version [$prev_version]";

      # remove previous link
      rm -f ${current_product}

      # relink current product to the previous version
      ln -sf ${basedir}/installation/${prev_version} ${current_product}

      # run product again. Now previous version is executed.
      run_product
  }
)