请教shell的一个问题

ricky_pc

( /usr/sbin/sshd -\? 2>&1 | grep -q OpenSSH ) 2>/dev/null || exit 0
和
if [ "$(stat -c %d/%i /)" = "$(stat -Lc %d/%i /proc/1/root 2>/dev/null)" ];
这两条分别是什么意思？

第一条中间的那个-\?以及第二条中的%d%i /具体是什么作用？

希望有高手能指导一下。不甚感激！

waker

1. 
   
2. The valid format sequences for files (without --file-system):
   
3. 
   
4. %a
   
5.     Access rights in octal
   
6. %A
   
7.     Access rights in human readable form
   
8. %b
   
9.     Number of blocks allocated (see %B)
   
10. %B
    
11.     The size in bytes of each block reported by %b
    
12. %C
    
13.     SELinux security context string
    
14. %d
    
15.     Device number in decimal
    
16. %D
    
17.     Device number in hex
    
18. %f
    
19.     Raw mode in hex
    
20. %F
    
21.     File type
    
22. %g
    
23.     Group ID of owner
    
24. %G
    
25.     Group name of owner
    
26. %h
    
27.     Number of hard links
    
28. %i
    
29.     Inode number
    
30. %n
    
31.     File name
    
32. %N
    
33.     Quoted file name with dereference if symbolic link
    
34. %o
    
35.     I/O block size
    
36. %s
    
37.     Total size, in bytes
    
38. %t
    
39.     Major device type in hex
    
40. %T
    
41.     Minor device type in hex
    
42. %u
    
43.     User ID of owner
    
44. %U
    
45.     User name of owner
    
46. %x
    
47.     Time of last access
    
48. %X
    
49.     Time of last access as seconds since Epoch
    
50. %y
    
51.     Time of last modification
    
52. %Y
    
53.     Time of last modification as seconds since Epoch
    
54. %z
    
55.     Time of last change
    
56. %Z
    
57.     Time of last change as seconds since Epoch
    
58. 
    
59. Valid format sequences for file systems:
    
60. 
    
61. %a
    
62.     Free blocks available to non-superuser
    
63. %b
    
64.     Total data blocks in file system
    
65. %c
    
66.     Total file nodes in file system
    
67. %d
    
68.     Free file nodes in file system
    
69. %f
    
70.     Free blocks in file system
    
71. %C
    
72.     SELinux security context string
    
73. %i
    
74.     File System ID in hex
    
75. %l
    
76.     Maximum length of filenames
    
77. %n
    
78.     File name
    
79. %s
    
80.     Block size (for faster transfers)
    
81. %S
    
82.     Fundamental block size (for block counts)
    
83. %t
    
84.     Type in hex
    
85. %T
    
86.     Type in human readable form
    
87. 
    
88. NOTE: your shell may have its own version of stat, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports.

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L_kernel

前面的这个

1. /usr/sbin/sshd -\? 2>&1

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很怪异，从来没有看过这种方式的命令选项。
后面那个

1. $(stat -c %d/%i /)

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指定输出信息的格式，输出包含/目录的文件系统信息。

ricky_pc

回复 3# L_kernel
这个是Ubuntu下面ssh的一个启动脚本。


   

iblicf

第一个就是个转义符号而已，，，sshd -? |grep -q OpenSSH

( /usr/sbin/sshd -\? 2>&1 | grep -q OpenSSH ) 2>/dev/null || exit 0 如果不是 OpenSSH 就退出