【Python】【解决】UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 1: ordinal not in range(128)

1、问题描述

今天在升级Ubuntu到14.04，使用命令行启动软件更新器，进行版本升级，结果开始升级就异常退出了，具体打印如下：

$update-manager -d
正在检查新版 Ubuntu
使用 'trusty.tar.gz.gpg' 对 'trusty.tar.gz' 进行验证 
正在提取 'trusty.tar.gz'
Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-r_0oij/trusty", line 10, in <module>
    sys.exit(main())
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/DistUpgradeMain.py", line 243, in main
    if app.run():
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/DistUpgradeController.py", line 1826, in run
    return self.fullUpgrade()
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/DistUpgradeController.py", line 1717, in fullUpgrade
    if not self.updateSourcesList():
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/DistUpgradeController.py", line 760, in updateSourcesList
    if not self.rewriteSourcesList(mirror_check=True):
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/DistUpgradeController.py", line 736, in rewriteSourcesList
    logging.debug("entry '%s' was disabled (unknown mirror)" % get_string_with_no_auth_from_source_entry(entry))
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/utils.py", line 89, in get_string_with_no_auth_from_source_entry
    return str(tmp)
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/sourceslist.py", line 232, in __str__
    return self.str().strip()
  File "/tmp/ubuntu-release-upgrader-r_0oij/DistUpgrade/sourceslist.py", line 256, in str
    line += u" #%s" % self.comment
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 1: ordinal not in range(128)

2、方案探索

主要错误是上面最后一行的Unicode解码问题，网上搜索说是读取文件时使用的编码默认时ascii而不是utf8，导致的错误；原始资料路径为：

http://blog.csdn.net/vincent_czz/article/details/7719012

在代码中加上如下几句即可。

import sys
reload(sys)
sys.setdefaultencoding('utf8')

http://docs.python.org/howto/unicode.html 这个是python的unicode编码API文档，英文好的同学可以看一下，加深理解。

3、解决方案

3.1 拷贝临时数据到本地

根据上面错误提示，拷贝升级包代码到本地，并修改权限为自己可以编辑

$sudo cp -R /tmp/ubuntu-release-upgrader-r_0oij ./upgrade
$sudo chown qunengrong:qunengrong upgrade/ -R

3.2 修正读取文件的代码

打开上面报错的文件，如DistUpgradeMain.py，进行编辑并保存；

## 原来为下面行
#import sys
## 改为下面的3行
import sys
reload(sys)
sys.setdefaultencoding('utf8')

3.3 手动启动升级

为了安全和防止升级过程被打断，建议提交到后台执行，如使用nohup，输入密码后按CTRL+Z终端，然后输入bg命令让其后台执行：

$nohup sudo ./trusty 
nohup: 忽略输入并把输出追加到"nohup.out"
[sudo] password for qunengrong: 

^Z
[1]+  已停止               nohup sudo ./trusty
qunengrong@qunengrong-Studio-1450 ~/tests/apt/upgrade
$bg
[1]+ nohup sudo ./trusty &

已经可以正常升级了，如下：