我该如何使用Python在*nix系统中获取文件的权限掩码,例如644或755?
是否有相应的函数或类可以实现此功能?非常感谢!
我该如何使用Python在*nix系统中获取文件的权限掩码,例如644或755?
是否有相应的函数或类可以实现此功能?非常感谢!
os.stat
是围绕着系统调用接口 stat(2) 的一个包装器。
>>> import os
>>> from stat import *
>>> os.stat("test.txt") # returns 10-tupel, you really want the 0th element ...
posix.stat_result(st_mode=33188, st_ino=57197013, \
st_dev=234881026L, st_nlink=1, st_uid=501, st_gid=20, st_size=0, \
st_atime=1300354697, st_mtime=1300354697, st_ctime=1300354697)
>>> os.stat("test.txt")[ST_MODE] # this is an int, but we like octal ...
33188
>>> oct(os.stat("test.txt")[ST_MODE])
'0100644'
从这里开始,您将认识到典型的八进制权限。
S_IRWXU 00700 mask for file owner permissions
S_IRUSR 00400 owner has read permission
S_IWUSR 00200 owner has write permission
S_IXUSR 00100 owner has execute permission
S_IRWXG 00070 mask for group permissions
S_IRGRP 00040 group has read permission
S_IWGRP 00020 group has write permission
S_IXGRP 00010 group has execute permission
S_IRWXO 00007 mask for permissions for others (not in group)
S_IROTH 00004 others have read permission
S_IWOTH 00002 others have write permission
S_IXOTH 00001 others have execute permission
你只对低位的比特位感兴趣,因此你可以截掉其余的部分:
>>> oct(os.stat("test.txt")[ST_MODE])[-3:]
'644'
>>> # or better
>>> oct(os.stat("test.txt").st_mode & 0o777)
注意:上面的部分确定文件类型,例如:S_IFMT 0170000 bitmask for the file type bitfields
S_IFSOCK 0140000 socket
S_IFLNK 0120000 symbolic link
S_IFREG 0100000 regular file
S_IFBLK 0060000 block device
S_IFDIR 0040000 directory
S_IFCHR 0020000 character device
S_IFIFO 0010000 FIFO
S_ISUID 0004000 set UID bit
S_ISGID 0002000 set-group-ID bit (see below)
S_ISVTX 0001000 sticky bit (see below)
我认为这是获取文件权限位最清晰的方法:
stat.S_IMODE(os.lstat("file").st_mode)
如果该文件是符号链接,则使用 os.lstat()
将会给出链接本身的模式,而 os.stat()
将解引用该链接。因此,我认为 os.lstat()
是最常用的。stat.S_IMODE()
可以获取“文件的权限位,加上粘着位、设置组 ID 位和设置用户 ID 位”。
以下是一个示例情况,给定普通文件 "testfile" 和指向它的符号链接 "testlink:"
import stat
import os
print oct(stat.S_IMODE(os.lstat("testlink").st_mode))
print oct(stat.S_IMODE(os.stat("testlink").st_mode))
这个脚本对我输出以下结果:
0777
0666
os.access("test.dat",os.R_OK)
>>> True
#Execute permissions
os.access("test.dat",os.X_OK)
>>> False
#And Combinations thereof
os.access("test.dat",os.R_OK or os.X_OK)
>>> True
os.access("test.dat",os.R_OK and os.X_OK)
>>> False
oct(os.stat('file').st_mode)[4:]
os.access(path, mode)
方法会在允许访问路径时返回 True
,否则返回 False
。
可用的模式包括:
例如,检查文件 /tmp/test.sh 是否具有执行权限:
ls -l /tmp/temp.sh
-rw-r--r-- 1 * * 0 Mar 2 12:05 /tmp/temp.sh
os.access('/tmp/temp.sh',os.X_OK)
False
after changing the file permission to +x
chmod +x /tmp/temp.sh
ls -l /tmp/temp.sh
-rwxr-xr-x 1 * * 0 Mar 2 12:05 /tmp/temp.sh
os.access('/tmp/temp.sh',os.X_OK)
True
import os
import stat
mode = os.stat("path_of_directory").st_mode
if not ((mode & stat.S_IWUSR):
print('not writable by user')
if not ((mode & stat.S_IWUSR) and (mode & stat.S_IWGRP) and (mode & stat.S_IWOTH)):
print('not writable by all')
S_IRWXU 00700 mask for file owner permissions
S_IRUSR 00400 owner has read permission
S_IWUSR 00200 owner has write permission
S_IXUSR 00100 owner has execute permission
S_IRWXG 00070 mask for group permissions
S_IRGRP 00040 group has read permission
S_IWGRP 00020 group has write permission
S_IXGRP 00010 group has execute permission
S_IRWXO 00007 mask for permissions for others (not in group)
S_IROTH 00004 others have read permission
S_IWOTH 00002 others have write permission
S_IXOTH 00001 others have execute permission
我相信os模块内有很多基于文件的函数。如果你运行 os.stat(filename)
,你总是可以解释结果。
os.stat
类似于C库的stat函数(在Linux上使用man 2 stat查看信息)
stats = os.stat('file.txt')
print(stats.st_mode)
如果您想要,可以使用Popen运行Bash stat命令:
正常的Bash命令:
jlc@server:~/NetBeansProjects/LineReverse$ stat -c '%A %a %n' revline.c
-rw-rw-r-- 664 revline.c
然后使用Python:
>>> from subprocess import Popen, PIPE
>>> fname = 'revline.c'
>>> cmd = "stat -c '%A %a %n' " + fname
>>> out = Popen(cmd, shell=True, stdout=PIPE).communicate()[0].split()[1].decode()
>>> out
'664'
如果你觉得需要搜索目录,这里还有另一种方法:
>>> from os import popen
>>> cmd = "stat -c '%A %a %n' *"
>>> fname = 'revline.c'
>>> for i in popen(cmd):
... p, m, n = i.split()
... if n != fname:
... continue
... print(m)
break
...
664
>>>
oct(os.stat("test.txt").st_mode & 0777)
- ncoghlanST_MODE
在stat
模块中,你导入了吗? - Carson Myersos.stat
看起来返回的是一个命名元组,因此您可以使用点符号访问其值。>> os.stat('.bashrc').st_mode
33188
>> os.stat('.bashrc').st_uid
1000
因此无需import stat
。 - jerblack