BASH 找不到使用 ~/in 路径存在的隐藏文件

Question

我有一个 BASH 脚本，它正在我的主目录中寻找一个隐藏文件。当我在尝试查找文件时指定绝对路径 /home/user/.foo 然后脚本会找到它但是如果我使用 ~/.foo 然后脚本找不到文件。有人可以解释为什么会发生这种情况以及我可以通过其他什么方式找到该文件。我希望能够在不同用户的主目录中找到该文件，而不仅仅是我自己的主目录。

很抱歉没有提供代码片段，但这里是

file="~/.foo"

[ -f $file ] && echo "foo 存在!"

然而这有效

file="home/user/.foo"

[ -f $file ] && echo "foo 存在!"

Answer 1

这是因为当波浪号是单词中的第一个未加引号的字符时，shell 只执行波浪号扩展。在

file="~/.foo"

波浪号用双引号引起来，因此未展开。最佳做法是始终使用 $HOME 当波浪号应该扩展到您的主目录(而不是像 ~user 中那样的其他用户的主目录。

来自 POSIX 的纯正涂料:

2.6.1 Tilde Expansion

A "tilde-prefix" consists of an unquoted <tilde> character at the beginning of a word, followed by all of the characters preceding the first unquoted <slash> in the word, or all the characters in the word if there is no <slash>. In an assignment (see XBD Variable Assignment), multiple tilde-prefixes can be used: at the beginning of the word (that is, following the <equals-sign> of the assignment), following any unquoted <colon>, or both. A tilde-prefix in an assignment is terminated by the first unquoted <colon> or <slash>. If none of the characters in the tilde-prefix are quoted, the characters in the tilde-prefix following the <tilde> are treated as a possible login name from the user database. A portable login name cannot contain characters outside the set given in the description of the LOGNAME environment variable in XBD Other Environment Variables. If the login name is null (that is, the tilde-prefix contains only the tilde), the tilde-prefix is replaced by the value of the variable HOME. If HOME is unset, the results are unspecified. Otherwise, the tilde-prefix shall be replaced by a pathname of the initial working directory associated with the login name obtained using the getpwnam() function as defined in the System Interfaces volume of POSIX.1-2008. If the system does not recognize the login name, the results are undefined.

The pathname resulting from tilde expansion shall be treated as if quoted to prevent it being altered by field splitting and pathname expansion.