Linux 中的 Umask 是什么？
基于 UNIX 的系统使用 Umask（用户文件创建模式掩码的缩写）为新创建的文件和目录设置默认权限。它通过屏蔽或减去这些权限来实现此目的。例如，在大多数情况下，通常的 Umask 设置的默认值为 022，我们创建的所有新文件都将从完全权限中减去 Umask 值（对于为 666 – 022 = 644 的文件）。Umask 是以用八进制或符号值表示。
八进制值（例如 027）— 这三位数字将影响用户、用户组和其他用户的最终权限。
符号值（例如 u=rwx，g=rx，o=rx）— 等效于八进制值 022。此处列出的符号权限并没有真正被 Umask 屏蔽或减去，而是值 u=rwx，g=rx，o=rx 将导致目录具有 u=rwx，g=rx，o=rx，并且文件具有 u=rw，g=r，o=r 权限，因为无法使用可执行x属性创建文件。
Linux umask 命令有什么用？
当有多个用户时，Linux 的 umask 命令将起到更为安全的特性。系统管理员可以确保通过正确设置 umask 值，不同的用户将默认使用安全权限创建文件，而不是稍后修复和手动设置这些权限，这可能有风险、复杂且耗时。
chmod 和 umask 有什么区别？
使用场景不一样，但 umask 相对于 chmod 的优势在于，它将影响该用户在整个系统范围内创建的所有文件和目录。使用 chmod，是专门为了更改每个文件的权限，而不是默认为设置的权限。
Linux Umask 是如何工作的？
基于 Unix 的操作系统具有一组属性，那就是用于定义用户读取R、写入W或执行X特定文件或目录。这些权限适用于三个称为 “权限类” 的类别，它们如下所示。
User即用户所有者：默认情况下是文件或文件夹的所有者或创建者。新文件的所有权默认属于此用户。
Group即用户所在组：对文件或文件夹共享相同访问级别或权限的用户集。
Other即其他用户组：定义为前两个类别中未包含的任何用户。这些用户尚未创建文件或文件夹，也不属于特定的用户组。此组包括未标识为用户或未属于用户组的每个人。当我们将文件或文件夹的权限级别设置为 Other （其他） 时，它会向访问该文件或文件夹的任何人授予权限级别访问权限。
我们还可以在左侧的符号表示中看到权限。
umask 命令的工作原理是在创建文件时剥离权限。在系统上，默认 umask 当前设置为八进制值 022。这是它在终端中的样子。
[root@host umask]# umask
0022要了解当 umask 设置为 022 时，文件和目录是使用哪些权限创建的，只需从 Linux 在 umask 之前为文件和目录设置的默认权限中减去该值，umask 为 666，目录为 777。
新文件：666 – 022 = 644
新目录：777 – 022 = 755
下面将创建一个文件，然后使用修改后的 stat 命令，该命令将在八进制模式下显示文件的权限。
[root@host umask]# touch newfile.txt
[root@host umask]# stat -c '%a' newfile.txt
644这些命令执行相同的操作，但这次使用目录。
[root@host umask]# mkdir newdirectory
[root@host umask]# stat -c '%a' newdirectory
755目录的 umask 值为 026 为所有者设置读取、写入和执行的权限，为组设置仅读取和执行的权限，以及为其他用户设置仅具有执行能力的权限，因为 777 – 027 = 751。
[root@host umask]# umask 026
[root@host umask]# umask
0026
[root@host umask]# mkdir testdir
[root@host umask]# stat -c '%a' testdir
751下面我们可以看到 unmask 的每个八进制值如何影响创建的新文件。
0：读取和写入。
1：读取和写入。
2：读取。
3：读取。
4：写入。
5：写入。
6：仅执行。
7：无权限。
以下是目录的值。
0：读取、写入和执行。
1：读取和写入。
2：读取和执行。
3：只读。
4：写入和执行。
5：只写。
6：仅执行。
7：无权限。
如何修改Umask值
只需在终端中键入 umask 即可找到 Linux umask 命令。可以使用 which 命令查找其二进制路径。
[root@host umask]# which umask
/usr/bin/umask如果要编辑默认 umask 值，而不是在每次登录时都再次设置，则可以编辑.profile并在底部附加 umask 命令。
[root@host ~]# cat .profile
# .bash_profile
# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
# User specific environment and startup programs
PATH=$PATH:$HOME/bin
export PATH
umask 0023也可以在特定用户的 .bashrc 主目录中完成此操作。
[root@host testuser]# cat .bashrc
# .bashrc
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
# Uncomment the following line if you don't like systemctl's auto-paging feature:
# export SYSTEMD_PAGER=
# User specific aliases and functions
umask 0023umask 命令语法
umask 的完整手册页条目如下。
umask [-p] [-S] [mode]
The user file-creation mask is set to mode.
If mode begins with a digit, it is interpreted as an octal number; otherwise it is interpreted as a symbolic mode mask similar to that accepted by chmod(1). If mode is omitted, the current value of the mask is printed.
The -S option causes the mask to be printed in symbolic form; the default output is an octal number.
If the -p option is supplied, and mode is omitted, the output is in a form that may be reused as input. The return status is 0 if the mode was successfully changed or if no mode argument was supplied, and false otherwise.要查看当前的 umask 值，我们使用 umask 命令。单独运行 umask 命令可提供在创建文件或文件夹时分配的默认权限。
[root@host ~]# umask
0022
[root@host ~]#要更改这些值，我们将使用以下命令。
[root@host ~]# umask ###
[root@host ~]# umask 022第一个命令中的 ### 符号用于代替实际的八进制数。
下面，我们可以看到八进制的翻译值以及它们之间的关系。
因此，当我们运行 ls 命令时，八进制或符号权限值显示在输出的开头。
[root@host ~]# ls
drwxr-xr-x 2 root root 4096 Apr 21 12:54 test/
-rw-r--r-- 1 root root 0 Apr 21 12:53 test.txt示例
正如之前所说，如果未更改默认设置，则使用访问模式 666 创建文件，使用 777 创建目录。在此示例中：
用于普通用户的默认 umask 002。使用此掩码，默认目录权限为 775，默认文件权限为 664。
root 用户的默认 umask 为 022，进入目录的默认权限为 755，默认文件权限为 644。
对于目录，基本权限为 （rwxrwxrwx） 0777，对于文件，基本权限为 0666 （rw-rw-rw）。
总之
umask 为 022 时，只能写入数据，但任何人都可以读取数据。
umask 为 077 适用于完全私有的系统。如果 umask 设置为 077，则其他用户无法读取或写入您的数据。
当与同一组中的其他用户共享数据时，umask 002 是很好的。您的群组成员可以创建和修改数据文件;组外的用户可以读取数据文件，但不能修改数据文件。将 umask 设置为 007 以完全排除非组成员的用户。
以下示例说明了 umask 如何影响 Linux 系统上的文件和目录的权限。首先，使用 ls 命令记下当前 shell 中文件和目录的默认 umask 权限：
让我们看看如果将 umask 设置为 0 会发生什么：$ umask$ ls -l$ touch nixcraft.txt$ mkdir app1$ ls -l
$ umask 0$ ls -l$ touch cyberciti.biz.txt$ mkdir myapp1$ ls -l
cyberciti.biz.txt 文件权限，用于其他更改，从 read 到 read and write。myapp1 目录权限，用于从 read 和 execute 更改为 read、write 和 execute。
接下来，设置 umask 077 在 shell 提示符处键入以下 umask 命令：
使用 mkdir 命令创建一个新目录，并使用 touch 命令创建一个新文件，如下所示：
使用 ls 命令列出文件详细信息，包括权限：
以下是我在 umask 设置为 077 时看到的内容：$ umask 077``$ mkdir dir1$ touch file``$ ls -ld dir1 file
drwx------ 2 vivek vivek 4096 2011-03-04 02:05 dir1
-rw------- 1 vivek vivek 0 2011-03-04 02:05 fileUmask代码
/* Copyright (C) 1991,1992,1995-2004,2005,2006 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/*
* POSIX Standard: 5.6 File Characteristics <sys/stat.h>
*/
#ifndef _SYS_STAT_H
#define _SYS_STAT_H 1
#include <features.h>
#include <bits/types.h> /* For __mode_t and __dev_t. */
#if defined __USE_XOPEN || defined __USE_MISC
# if defined __USE_XOPEN || defined __USE_XOPEN2K
# define __need_time_t
# endif
# ifdef __USE_MISC
# define __need_timespec
# endif
# include <time.h> /* For time_t resp. timespec. */
#endif
#if defined __USE_XOPEN || defined __USE_XOPEN2K
/* The Single Unix specification says that some more types are
available here. */
# ifndef __dev_t_defined
typedef __dev_t dev_t;
# define __dev_t_defined
# endif
# ifndef __gid_t_defined
typedef __gid_t gid_t;
# define __gid_t_defined
# endif
# ifndef __ino_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __ino_t ino_t;
# else
typedef __ino64_t ino_t;
# endif
# define __ino_t_defined
# endif
# ifndef __mode_t_defined
typedef __mode_t mode_t;
# define __mode_t_defined
# endif
# ifndef __nlink_t_defined
typedef __nlink_t nlink_t;
# define __nlink_t_defined
# endif
# ifndef __off_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __off_t off_t;
# else
typedef __off64_t off_t;
# endif
# define __off_t_defined
# endif
# ifndef __uid_t_defined
typedef __uid_t uid_t;
# define __uid_t_defined
# endif
#endif /* X/Open */
#ifdef __USE_UNIX98
# ifndef __blkcnt_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __blkcnt_t blkcnt_t;
# else
typedef __blkcnt64_t blkcnt_t;
# endif
# define __blkcnt_t_defined
# endif
# ifndef __blksize_t_defined
typedef __blksize_t blksize_t;
# define __blksize_t_defined
# endif
#endif /* Unix98 */
__BEGIN_DECLS
#include <bits/stat.h>
#if defined __USE_BSD || defined __USE_MISC || defined __USE_XOPEN
# define S_IFMT __S_IFMT
# define S_IFDIR __S_IFDIR
# define S_IFCHR __S_IFCHR
# define S_IFBLK __S_IFBLK
# define S_IFREG __S_IFREG
# ifdef __S_IFIFO
# define S_IFIFO __S_IFIFO
# endif
# ifdef __S_IFLNK
# define S_IFLNK __S_IFLNK
# endif
# if (defined __USE_BSD || defined __USE_MISC || defined __USE_UNIX98) \
&& defined __S_IFSOCK
# define S_IFSOCK __S_IFSOCK
# endif
#endif
/* Test macros for file types. */
#define __S_ISTYPE(mode, mask) (((mode) & __S_IFMT) == (mask))
#define S_ISDIR(mode) __S_ISTYPE((mode), __S_IFDIR)
#define S_ISCHR(mode) __S_ISTYPE((mode), __S_IFCHR)
#define S_ISBLK(mode) __S_ISTYPE((mode), __S_IFBLK)
#define S_ISREG(mode) __S_ISTYPE((mode), __S_IFREG)
#ifdef __S_IFIFO
# define S_ISFIFO(mode) __S_ISTYPE((mode), __S_IFIFO)
#endif
#ifdef __S_IFLNK
# define S_ISLNK(mode) __S_ISTYPE((mode), __S_IFLNK)
#endif
#if defined __USE_BSD && !defined __S_IFLNK
# define S_ISLNK(mode) 0
#endif
#if (defined __USE_BSD || defined __USE_UNIX98) \
&& defined __S_IFSOCK
# define S_ISSOCK(mode) __S_ISTYPE((mode), __S_IFSOCK)
#endif
/* These are from POSIX.1b. If the objects are not implemented using separate
distinct file types, the macros always will evaluate to zero. Unlike the
other S_* macros the following three take a pointer to a `struct stat'
object as the argument. */
#ifdef __USE_POSIX199309
# define S_TYPEISMQ(buf) __S_TYPEISMQ(buf)
# define S_TYPEISSEM(buf) __S_TYPEISSEM(buf)
# define S_TYPEISSHM(buf) __S_TYPEISSHM(buf)
#endif
/* Protection bits. */
#define S_ISUID __S_ISUID /* Set user ID on execution. */
#define S_ISGID __S_ISGID /* Set group ID on execution. */
#if defined __USE_BSD || defined __USE_MISC || defined __USE_XOPEN
/* Save swapped text after use (sticky bit). This is pretty well obsolete. */
# define S_ISVTX __S_ISVTX
#endif
#define S_IRUSR __S_IREAD /* Read by owner. */
#define S_IWUSR __S_IWRITE /* Write by owner. */
#define S_IXUSR __S_IEXEC /* Execute by owner. */
/* Read, write, and execute by owner. */
#define S_IRWXU (__S_IREAD|__S_IWRITE|__S_IEXEC)
#if defined __USE_MISC && defined __USE_BSD
# define S_IREAD S_IRUSR
# define S_IWRITE S_IWUSR
# define S_IEXEC S_IXUSR
#endif
#define S_IRGRP (S_IRUSR >> 3) /* Read by group. */
#define S_IWGRP (S_IWUSR >> 3) /* Write by group. */
#define S_IXGRP (S_IXUSR >> 3) /* Execute by group. */
/* Read, write, and execute by group. */
#define S_IRWXG (S_IRWXU >> 3)
#define S_IROTH (S_IRGRP >> 3) /* Read by others. */
#define S_IWOTH (S_IWGRP >> 3) /* Write by others. */
#define S_IXOTH (S_IXGRP >> 3) /* Execute by others. */
/* Read, write, and execute by others. */
#define S_IRWXO (S_IRWXG >> 3)
#ifdef __USE_BSD
/* Macros for common mode bit masks. */
# define ACCESSPERMS (S_IRWXU|S_IRWXG|S_IRWXO) /* 0777 */
# define ALLPERMS (S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO)/* 07777 */
# define DEFFILEMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)/* 0666*/
# define S_BLKSIZE 512 /* Block size for `st_blocks'. */
#endif
#ifndef __USE_FILE_OFFSET64
/* Get file attributes for FILE and put them in BUF. */
extern int stat (__const char *__restrict __file,
struct stat *__restrict __buf) __THROW __nonnull ((1, 2));
/* Get file attributes for the file, device, pipe, or socket
that file descriptor FD is open on and put them in BUF. */
extern int fstat (int __fd, struct stat *__buf) __THROW __nonnull ((2));
#else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (stat, (__const char *__restrict __file,
struct stat *__restrict __buf), stat64)
__nonnull ((1, 2));
extern int __REDIRECT_NTH (fstat, (int __fd, struct stat *__buf), fstat64)
__nonnull ((2));
# else
# define stat stat64
# define fstat fstat64
# endif
#endif
#ifdef __USE_LARGEFILE64
extern int stat64 (__const char *__restrict __file,
struct stat64 *__restrict __buf) __THROW __nonnull ((1, 2));
extern int fstat64 (int __fd, struct stat64 *__buf) __THROW __nonnull ((2));
#endif
#ifdef __USE_ATFILE
/* Similar to stat, get the attributes for FILE and put them in BUF.
Relative path names are interpreted relative to FD unless FD is
AT_FDCWD. */
# ifndef __USE_FILE_OFFSET64
extern int fstatat (int __fd, __const char *__restrict __file,
struct stat *__restrict __buf, int __flag)
__THROW __nonnull ((2, 3));
# else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (fstatat, (int __fd, __const char *__restrict __file,
struct stat *__restrict __buf,
int __flag),
fstatat64) __nonnull ((2, 3));
# else
# define fstatat fstatat64
# endif
# endif
extern int fstatat64 (int __fd, __const char *__restrict __file,
struct stat64 *__restrict __buf, int __flag)
__THROW __nonnull ((2, 3));
#endif
#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
# ifndef __USE_FILE_OFFSET64
/* Get file attributes about FILE and put them in BUF.
If FILE is a symbolic link, do not follow it. */
extern int lstat (__const char *__restrict __file,
struct stat *__restrict __buf) __THROW __nonnull ((1, 2));
# else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (lstat,
(__const char *__restrict __file,
struct stat *__restrict __buf), lstat64)
__nonnull ((1, 2));
# else
# define lstat lstat64
# endif
# endif
# ifdef __USE_LARGEFILE64
extern int lstat64 (__const char *__restrict __file,
struct stat64 *__restrict __buf)
__THROW __nonnull ((1, 2));
# endif
#endif
/* Set file access permissions for FILE to MODE.
If FILE is a symbolic link, this affects its target instead. */
extern int chmod (__const char *__file, __mode_t __mode)
__THROW __nonnull ((1));
#ifdef __USE_BSD
/* Set file access permissions for FILE to MODE.
If FILE is a symbolic link, this affects the link itself
rather than its target. */
extern int lchmod (__const char *__file, __mode_t __mode)
__THROW __nonnull ((1));
#endif
/* Set file access permissions of the file FD is open on to MODE. */
#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern int fchmod (int __fd, __mode_t __mode) __THROW;
#endif
#ifdef __USE_ATFILE
/* Set file access permissions of FILE relative to
the directory FD is open on. */
extern int fchmodat (int __fd, __const char *__file, __mode_t mode, int __flag)
__THROW __nonnull ((2)) __wur;
#endif /* Use ATFILE. */
/* Set the file creation mask of the current process to MASK,
and return the old creation mask. */
extern __mode_t umask (__mode_t __mask) __THROW;
#ifdef __USE_GNU
/* Get the current `umask' value without changing it.
This function is only available under the GNU Hurd. */
extern __mode_t getumask (void) __THROW;
#endif
/* Create a new directory named PATH, with permission bits MODE. */
extern int mkdir (__const char *__path, __mode_t __mode)
__THROW __nonnull ((1));
#ifdef __USE_ATFILE
/* Like mkdir, create a new directory with permission bits MODE. But
interpret relative PATH names relative to the directory associated
with FD. */
extern int mkdirat (int __fd, __const char *__path, __mode_t __mode)
__THROW __nonnull ((2));
#endif
/* Create a device file named PATH, with permission and special bits MODE
and device number DEV (which can be constructed from major and minor
device numbers with the `makedev' macro above). */
#if defined __USE_MISC || defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern int mknod (__const char *__path, __mode_t __mode, __dev_t __dev)
__THROW __nonnull ((1));
#endif
#ifdef __USE_ATFILE
/* Like mknod, create a new device file with permission bits MODE and
device number DEV. But interpret relative PATH names relative to
the directory associated with FD. */
extern int mknodat (int __fd, __const char *__path, __mode_t __mode,
__dev_t __dev) __THROW __nonnull ((2));
#endif
/* Create a new FIFO named PATH, with permission bits MODE. */
extern int mkfifo (__const char *__path, __mode_t __mode)
__THROW __nonnull ((1));
#ifdef __USE_ATFILE
/* Like mkfifo, create a new FIFO with permission bits MODE. But
interpret relative PATH names relative to the directory associated
with FD. */
extern int mkfifoat (int __fd, __const char *__path, __mode_t __mode)
__THROW __nonnull ((2));
#endif
/* To allow the `struct stat' structure and the file type `mode_t'
bits to vary without changing shared library major version number,
the `stat' family of functions and `mknod' are in fact inline
wrappers around calls to `xstat', `fxstat', `lxstat', and `xmknod',
which all take a leading version-number argument designating the
data structure and bits used. <bits/stat.h> defines _STAT_VER with
the version number corresponding to `struct stat' as defined in
that file; and _MKNOD_VER with the version number corresponding to
the S_IF* macros defined therein. It is arranged that when not
inlined these function are always statically linked; that way a
dynamically-linked executable always encodes the version number
corresponding to the data structures it uses, so the `x' functions
in the shared library can adapt without needing to recompile all
callers. */
#ifndef _STAT_VER
# define _STAT_VER 0
#endif
#ifndef _MKNOD_VER
# define _MKNOD_VER 0
#endif
/* Wrappers for stat and mknod system calls. */
#ifndef __USE_FILE_OFFSET64
extern int __fxstat (int __ver, int __fildes, struct stat *__stat_buf)
__THROW __nonnull ((3));
extern int __xstat (int __ver, __const char *__filename,
struct stat *__stat_buf) __THROW __nonnull ((2, 3));
extern int __lxstat (int __ver, __const char *__filename,
struct stat *__stat_buf) __THROW __nonnull ((2, 3));
extern int __fxstatat (int __ver, int __fildes, __const char *__filename,
struct stat *__stat_buf, int __flag)
__THROW __nonnull ((3, 4));
#else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (__fxstat, (int __ver, int __fildes,
struct stat *__stat_buf), __fxstat64)
__nonnull ((3));
extern int __REDIRECT_NTH (__xstat, (int __ver, __const char *__filename,
struct stat *__stat_buf), __xstat64)
__nonnull ((2, 3));
extern int __REDIRECT_NTH (__lxstat, (int __ver, __const char *__filename,
struct stat *__stat_buf), __lxstat64)
__nonnull ((2, 3));
extern int __REDIRECT_NTH (__fxstatat, (int __ver, int __fildes,
__const char *__filename,
struct stat *__stat_buf, int __flag),
__fxstatat64) __nonnull ((3, 4));
# else
# define __fxstat __fxstat64
# define __xstat __xstat64
# define __lxstat __lxstat64
# endif
#endif
#ifdef __USE_LARGEFILE64
extern int __fxstat64 (int __ver, int __fildes, struct stat64 *__stat_buf)
__THROW __nonnull ((3));
extern int __xstat64 (int __ver, __const char *__filename,
struct stat64 *__stat_buf) __THROW __nonnull ((2, 3));
extern int __lxstat64 (int __ver, __const char *__filename,
struct stat64 *__stat_buf) __THROW __nonnull ((2, 3));
extern int __fxstatat64 (int __ver, int __fildes, __const char *__filename,
struct stat64 *__stat_buf, int __flag)
__THROW __nonnull ((3, 4));
#endif
extern int __xmknod (int __ver, __const char *__path, __mode_t __mode,
__dev_t *__dev) __THROW __nonnull ((2, 4));
extern int __xmknodat (int __ver, int __fd, __const char *__path,
__mode_t __mode, __dev_t *__dev)
__THROW __nonnull ((3, 5));
#if defined __GNUC__ && __GNUC__ >= 2
/* Inlined versions of the real stat and mknod functions. */
extern __inline__ int
__NTH (stat (__const char *__path, struct stat *__statbuf))
{
return __xstat (_STAT_VER, __path, __statbuf);
}
# if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern __inline__ int
__NTH (lstat (__const char *__path, struct stat *__statbuf))
{
return __lxstat (_STAT_VER, __path, __statbuf);
}
# endif
extern __inline__ int
__NTH (fstat (int __fd, struct stat *__statbuf))
{
return __fxstat (_STAT_VER, __fd, __statbuf);
}
# ifdef __USE_ATFILE
extern __inline__ int
__NTH (fstatat (int __fd, __const char *__filename, struct stat *__statbuf,
int __flag))
{
return __fxstatat (_STAT_VER, __fd, __filename, __statbuf, __flag);
}
# endif
# if defined __USE_MISC || defined __USE_BSD
extern __inline__ int
__NTH (mknod (__const char *__path, __mode_t __mode, __dev_t __dev))
{
return __xmknod (_MKNOD_VER, __path, __mode, &__dev);
}
# endif
# ifdef __USE_ATFILE
extern __inline__ int
__NTH (mknodat (int __fd, __const char *__path, __mode_t __mode,
__dev_t __dev))
{
return __xmknodat (_MKNOD_VER, __fd, __path, __mode, &__dev);
}
# endif
# if defined __USE_LARGEFILE64 \
&& (! defined __USE_FILE_OFFSET64 \
|| (defined __REDIRECT_NTH && defined __OPTIMIZE__))
extern __inline__ int
__NTH (stat64 (__const char *__path, struct stat64 *__statbuf))
{
return __xstat64 (_STAT_VER, __path, __statbuf);
}
# if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern __inline__ int
__NTH (lstat64 (__const char *__path, struct stat64 *__statbuf))
{
return __lxstat64 (_STAT_VER, __path, __statbuf);
}
# endif
extern __inline__ int
__NTH (fstat64 (int __fd, struct stat64 *__statbuf))
{
return __fxstat64 (_STAT_VER, __fd, __statbuf);
}
# ifdef __USE_GNU
extern __inline__ int
__NTH (fstatat64 (int __fd, __const char *__filename, struct stat64 *__statbuf,
int __flag))
{
return __fxstatat64 (_STAT_VER, __fd, __filename, __statbuf, __flag);
}
# endif
# endif
#endif
__END_DECLS
问题来了
1：我们在Linux下执行umask命令后可以看到0022，第一个0是特殊权限，特殊权限又是什么呢？
2：Windows下的NFS权限有没有Umask这么一个说法？还是仅仅基于ACL来控制呢？