在Bash中如何测试一个字符串是否比另一个字符串“更大"? [英] How does testing if a string is 'greater' than another work in Bash?

问题描述

在Bash中，我可以编写以下测试

In Bash I can write the following test

[[ "f" > "a" ]]

导致返回0，即true. bash实际上如何执行此字符串比较?根据我的理解，>进行整数比较.是否尝试比较操作数的ASCII值?

which results in returning 0, i.e. true. How does bash actually perform this string comparison? From my understanding > does an integer comparison. Does it try to compare the ASCII value of the operands?

推荐答案

来自help test:

  STRING1 > STRING2
                 True if STRING1 sorts after STRING2 lexicographically.

在内部，bash为此使用strcoll()或strcmp():

Internally, bash either uses strcoll() or strcmp() for that:

else if ((op[0] == '>' || op[0] == '<') && op[1] == '\0')
  {
    if (shell_compatibility_level > 40 && flags & TEST_LOCALE)
      return ((op[0] == '>') ? (strcoll (arg1, arg2) > 0) : (strcoll (arg1, arg2) < 0));
    else
      return ((op[0] == '>') ? (strcmp (arg1, arg2) > 0) : (strcmp (arg1, arg2) < 0));
  }

后者实际上是比较ASCII码，前者(启用语言环境时使用)执行更具体的比较，该比较适合在给定的语言环境中进行排序.

The latter actually compares ASCII codes, the former (used when locale is enabled) performs a more specific comparison which is suitable for sorting in given locale.

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