我写一些可以用来创建Linux用户帐户的Web UI页面。此Web UI将用于CentOS 6(源自RHEL 6)。我发现关于什么构成有效的Linux用户名的不一致和不完整的信息。我去源，检查一个Linux shadow-utils源包，但我不能确保我正在看的版本实际上是作为CentOS 6的一部分相同。
下面是我目前使用的代码片段，其中包括从shadow-utils包4.1.4.3中复制/粘贴注释，加上一些我自己的注释，以及一个Java正则表达式搜索， utils源。
在chkname.c中引用的“is_valid_name()”检查显然不是从Linux上的useradd命令使用的，因为注释(和C代码源)不允许以数字开头的名称。但是，useradd允许创建一个类似“1234”的帐户。
我希望帮助调整从我现在到什么是更正确的，以及关于如何实现useradd.c与一些稍微不同的is_valid_name函数的信息。
谢谢！
艾伦
- /**
- * Define constants for use in isNameLinuxCompatible(...) method.
- *
- * The source for the Linux compatible user name rule is is_valid_name(...) a function in the "shadow" package
- * for Linux. The source file for that function has a comment as follows:
- * User/group names must match [a-z_][a-z0-9_-]*[$]
- * That expression is a little loose/sloppy since
- * (1) the trailing $ sign is optional,and
- * (2) uppercase A-Z is also ok (and case is significant,'A' != 'a').
- *
- * We deal with (1) by using the [$]? form where the ? means zero or more characters (aka "greedy").
- * We deal with (2) by using the CASE_INSENSITIVE option.
- *
- * Another way to express this is:
- * 1st character: a-z_ required at least one char
- * chars other than first and last: a-z0-9_- optional
- * last character: $ optional
- * Max length is 31. Min length is 1.
- *
- * NOTE: The initial ^ and final $ below are important since we need the entire string to satisfy the rule,* from beginning to end.
- *
- * See http://download.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html for reference info on pattern matching.
- */
- private static final String LINUX_USERNAME_REGEX = "^[a-z_][a-z0-9_-]*[$]?$";
- private static final Pattern LINUX_USERNAME_PATTERN = Pattern.compile(LINUX_USERNAME_REGEX,Pattern.CASE_INSENSITIVE);
- private static final int LINUX_USERNAME_MINLENGTH = 1;
- private static final int LINUX_USERNAME_MAXLENGTH = 31;
- /**
- * See if username is compatible with standard Linux rules for usernames,in terms of length and
- * in terms of content.
- *
- * @param username the name to be checked for validity
- * @return true if Linux compatible,else false
- */
- public boolean isNameLinuxCompatible (final String username) {
- boolean nameOK = false;
- if (username != null) {
- int len = username.length();
- if ((len >= LINUX_USERNAME_MINLENGTH) && (len <= LINUX_USERNAME_MAXLENGTH)) {
- Matcher m = LINUX_USERNAME_PATTERN.matcher(username);
- nameOK = m.find();
- }
- }
- return (nameOK);
- }
