没有 cd 命令的手册页
No man page for the cd command
Ubuntu Linux 15.10 - 我刚刚注意到 cd
没有手册页
这似乎有点奇怪。
我试过了：
man cd
在 cmd 行，我回来了
No manual entry for cd
我试图找到关于
的文档
cd -
在最后一个目录和当前目录之间切换非常方便
和cd --
这似乎是
的别名
cd ~
我是不是遗漏了一些非常明显的东西，还是应该提供手册页？
cd 不是命令，它内置于您的 shell 中。这是必要的，因为您当前的工作目录由 PWD 环境变量控制，该变量以 pwd 或 "print working directory" 命令命名。
子进程不能更改父进程的环境变量。因此，如果您的 shell 运行 /bin/cd 更改了 PWD，它只会影响 /bin/cd 和任何它 运行。它不会改变 shell 的 PWD.
某些系统，如 OS X 和 CentOS，将 cd 手册页映射到 builtin，其中列出了所有 shell 内置插件和让您知道您应该查看 shell 的手册页。
你可以用echo $SHELL检查你有什么shell，它可能是bash。
bash 手册页的相关摘录，涵盖 cd -
的用法
cd [-L|[-P [-e]] [-@]] [dir]
Change the current directory to dir.
...
An argument of -
is converted to $OLDPWD before the directory change is attempted. If a non-
empty directory name from CDPATH is used, or if - is the first argument, and
the directory change is successful, the absolute pathname of the new working
directory is written to the standard output. The return value is true if the
directory was successfully changed; false otherwise.
cd 是内置的 shell 命令。
$ type cd
cd is a shell builtin
您可以使用
在 Bash 上打开 cd 的帮助页面
$ help cd
当前显示 (Ubuntu 16.04):
$ help cd
cd: cd [-L|[-P [-e]] [-@]] [dir]
Change the shell working directory.
Change the current directory to DIR. The default DIR is the value of the
HOME shell variable.
The variable CDPATH defines the search path for the directory containing
DIR. Alternative directory names in CDPATH are separated by a colon (:).
A null directory name is the same as the current directory. If DIR begins
with a slash (/), then CDPATH is not used.
If the directory is not found, and the shell option `cdable_vars' is set,
the word is assumed to be a variable name. If that variable has a value,
its value is used for DIR.
Options:
-L force symbolic links to be followed: resolve symbolic links in
DIR after processing instances of `..'
-P use the physical directory structure without following symbolic
links: resolve symbolic links in DIR before processing instances
of `..'
-e if the -P option is supplied, and the current working directory
cannot be determined successfully, exit with a non-zero status
-@ on systems that support it, present a file with extended attributes
as a directory containing the file attributes
The default is to follow symbolic links, as if `-L' were specified.
`..' is processed by removing the immediately previous pathname component
back to a slash or the beginning of DIR.
Exit Status:
Returns 0 if the directory is changed, and if $PWD is set successfully when
-P is used; non-zero otherwise.
很遗憾，它无法回答您的问题。然而，是 文档。
您可以使用
$ man builtins
它使用我的默认查看器 less 打开许多帮助页面。我可以通过按 / 键找到 cd 的帮助，然后输入 cd，然后输入 Enter，然后按两次 n 将我带到子字符串的第三个实例，和帮助，上面写着：
cd [-L|[-P [-e]] [-@]] [dir]
Change the current directory to dir. if dir is not supplied,
the value of the HOME shell variable is the default. Any addi‐
tional arguments following dir are ignored. The variable CDPATH
defines the search path for the directory containing dir: each
directory name in CDPATH is searched for dir. Alternative
directory names in CDPATH are separated by a colon (:). A null
directory name in CDPATH is the same as the current directory,
i.e., ``.''. If dir begins with a slash (/), then CDPATH is not
used. The -P option causes cd to use the physical directory
structure by resolving symbolic links while traversing dir and
before processing instances of .. in dir (see also the -P option
to the set builtin command); the -L option forces symbolic links
to be followed by resolving the link after processing instances
of .. in dir. If .. appears in dir, it is processed by removing
the immediately previous pathname component from dir, back to a
slash or the beginning of dir. If the -e option is supplied
with -P, and the current working directory cannot be success‐
fully determined after a successful directory change, cd will
return an unsuccessful status. On systems that support it, the
-@ option presents the extended attributes associated with a
file as a directory. An argument of - is converted to $OLDPWD
before the directory change is attempted. If a non-empty direc‐
tory name from CDPATH is used, or if - is the first argument,
and the directory change is successful, the absolute pathname of
the new working directory is written to the standard output.
The return value is true if the directory was successfully
changed; false otherwise.
寻找关于倒数第七行的-参数：
An argument of - is converted to $OLDPWD before the directory change is attempted.
请注意，没有 -- 参数 - 这似乎意味着它实际上忽略了它。
Ubuntu Linux 15.10 - 我刚刚注意到 cd
这似乎有点奇怪。
我试过了：
man cd
在 cmd 行，我回来了
No manual entry for cd
我试图找到关于
的文档cd -
在最后一个目录和当前目录之间切换非常方便
和cd --
这似乎是
的别名cd ~
我是不是遗漏了一些非常明显的东西，还是应该提供手册页？
cd 不是命令，它内置于您的 shell 中。这是必要的，因为您当前的工作目录由 PWD 环境变量控制，该变量以 pwd 或 "print working directory" 命令命名。
子进程不能更改父进程的环境变量。因此，如果您的 shell 运行 /bin/cd 更改了 PWD，它只会影响 /bin/cd 和任何它 运行。它不会改变 shell 的 PWD.
某些系统，如 OS X 和 CentOS，将 cd 手册页映射到 builtin，其中列出了所有 shell 内置插件和让您知道您应该查看 shell 的手册页。
你可以用echo $SHELL检查你有什么shell，它可能是bash。
bash 手册页的相关摘录，涵盖 cd -
cd [-L|[-P [-e]] [-@]] [dir]
Change the current directory to dir.
...
An argument of -
is converted to $OLDPWD before the directory change is attempted. If a non-
empty directory name from CDPATH is used, or if - is the first argument, and
the directory change is successful, the absolute pathname of the new working
directory is written to the standard output. The return value is true if the
directory was successfully changed; false otherwise.
cd 是内置的 shell 命令。
$ type cd
cd is a shell builtin
您可以使用
在 Bash 上打开cd 的帮助页面
$ help cd
当前显示 (Ubuntu 16.04):
$ help cd
cd: cd [-L|[-P [-e]] [-@]] [dir]
Change the shell working directory.
Change the current directory to DIR. The default DIR is the value of the
HOME shell variable.
The variable CDPATH defines the search path for the directory containing
DIR. Alternative directory names in CDPATH are separated by a colon (:).
A null directory name is the same as the current directory. If DIR begins
with a slash (/), then CDPATH is not used.
If the directory is not found, and the shell option `cdable_vars' is set,
the word is assumed to be a variable name. If that variable has a value,
its value is used for DIR.
Options:
-L force symbolic links to be followed: resolve symbolic links in
DIR after processing instances of `..'
-P use the physical directory structure without following symbolic
links: resolve symbolic links in DIR before processing instances
of `..'
-e if the -P option is supplied, and the current working directory
cannot be determined successfully, exit with a non-zero status
-@ on systems that support it, present a file with extended attributes
as a directory containing the file attributes
The default is to follow symbolic links, as if `-L' were specified.
`..' is processed by removing the immediately previous pathname component
back to a slash or the beginning of DIR.
Exit Status:
Returns 0 if the directory is changed, and if $PWD is set successfully when
-P is used; non-zero otherwise.
很遗憾，它无法回答您的问题。然而，是 文档。
您可以使用
$ man builtins
它使用我的默认查看器 less 打开许多帮助页面。我可以通过按 / 键找到 cd 的帮助，然后输入 cd，然后输入 Enter，然后按两次 n 将我带到子字符串的第三个实例，和帮助，上面写着：
cd [-L|[-P [-e]] [-@]] [dir]
Change the current directory to dir. if dir is not supplied,
the value of the HOME shell variable is the default. Any addi‐
tional arguments following dir are ignored. The variable CDPATH
defines the search path for the directory containing dir: each
directory name in CDPATH is searched for dir. Alternative
directory names in CDPATH are separated by a colon (:). A null
directory name in CDPATH is the same as the current directory,
i.e., ``.''. If dir begins with a slash (/), then CDPATH is not
used. The -P option causes cd to use the physical directory
structure by resolving symbolic links while traversing dir and
before processing instances of .. in dir (see also the -P option
to the set builtin command); the -L option forces symbolic links
to be followed by resolving the link after processing instances
of .. in dir. If .. appears in dir, it is processed by removing
the immediately previous pathname component from dir, back to a
slash or the beginning of dir. If the -e option is supplied
with -P, and the current working directory cannot be success‐
fully determined after a successful directory change, cd will
return an unsuccessful status. On systems that support it, the
-@ option presents the extended attributes associated with a
file as a directory. An argument of - is converted to $OLDPWD
before the directory change is attempted. If a non-empty direc‐
tory name from CDPATH is used, or if - is the first argument,
and the directory change is successful, the absolute pathname of
the new working directory is written to the standard output.
The return value is true if the directory was successfully
changed; false otherwise.
寻找关于倒数第七行的-参数：
An argument of
-is converted to$OLDPWDbefore the directory change is attempted.
请注意，没有 -- 参数 - 这似乎意味着它实际上忽略了它。