The Unix Shell. Permissions

Transcription

1 The Unix Shell Copyright Software Carpentry 2010 This work is licensed under the Creative Commons Attribution License See for more information.

2 shell

3 shell pwd, mkdir, cp,...

4 shell pwd, mkdir, cp,... *

5 shell pwd, mkdir, cp,... * >,

6 shell pwd, mkdir, cp,... * >, Who can see what?

7 shell pwd, mkdir, cp,... * >, Who can see what? change

8 shell pwd, mkdir, cp,... * >, Who can see what? change run

9 Simplified version of Unix permissions

10 Simplified version of Unix permissions Windows uses similar concepts

11 Simplified version of Unix permissions Windows uses similar concepts but there is no exact translation between the two

12 user

13 user Has unique user name and user ID

14 user Has unique user name and user ID User name is text: "imhotep", "larry", "vlad",

15 user Has unique user name and user ID User name is text: "imhotep", "larry", "vlad", User ID is numeric (easier for computer to store)

16 user group

17 user group Has unique group name and group ID

18 user group Has unique group name and group ID User can belongs to zero or more groups

19 user group Has unique group name and group ID User can belongs to zero or more groups List is usually stored in /etc/group

20 user group all

21 user group all Everyone else

22 user group all Has user and group IDs

23 read user group all

24 read user group all write

25 read user group all write execute

26 user group all read write execute

27 File's owner can read and write it user group all read write execute

28 File's owner can read and write it Others in group can read user group all read write execute

29 File's can read and write it Others in group can read That's all user group all read write execute

30 $ cd labs $ ls safety.txt setup waiver.txt $

31 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $

32 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ means "executable"

33 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $

34 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ name

35 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ last modified

36 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ size (in bytes)

37 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ group owner

38 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ user owner

39 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ don't care (for now)

40 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ permissions

41 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x

42 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x file type

43 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x file type '-' for regular

44 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x file type '-' for regular 'd' for directory

45 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x user owner permissions

46 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x group owner permissions

47 $ cd labs $ ls safety.txt setup waiver.txt $ ls -F safety.txt setup* waiver.txt $ ls -l $ -rwxr-xr-x everyone else's permissions

48 $ ls -a -l drwxr-xr-x 1 vlad bio :55. drwxr-xr-x 1 vlad bio :11.. -rw-rw-r-- 1 vlad bio :22 safety -rwxr-xr-x 1 vlad bio :04 setup -rw-rw-r-- 1 vlad bio :23 waiver $

49 $ ls -a -l drwxr-xr-x 1 vlad bio :55. drwxr-xr-x 1 vlad bio :11.. -rw-rw-r-- 1 vlad bio :22 safety -rwxr-xr-x 1 vlad bio :04 setup -rw-rw-r-- 1 vlad bio :23 waiver $

50 $ ls -a -l drwxr-xr-x 1 vlad bio :55. drwxr-xr-x 1 vlad bio :11.. -rw-rw-r-- 1 vlad bio :22 safety -rwxr-xr-x 1 vlad bio :04 setup -rw-rw-r-- 1 vlad bio :23 waiver $

51 What does "execute" mean for directories?

52 What does "execute" mean for directories? Gives the right to traverse the directory

53 What does "execute" mean for directories? Gives the right to traverse the directory vlad venus mars pluto

54 What does "execute" mean for directories? Gives the right to traverse the directory vlad venus mars pluto notes notes notes

55 What does "execute" mean for directories? Gives the right to traverse the directory vlad venus mars pluto notes notes notes

56 What does "execute" mean for directories? Gives the right to traverse the directory vlad r-x venus mars pluto notes notes notes

57 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes r-x venus mars pluto notes notes notes

58 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes r-x venus mars pluto notes notes notes

59 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes r-- venus mars pluto notes notes notes

60 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes r-- $ ls mars mars/notes venus mars pluto notes notes notes

61 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes --x $ ls mars mars/notes venus mars pluto notes notes notes

62 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes $ ls mars mars/notes --x $ ls pluto venus mars pluto notes notes notes

63 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes --x $ ls mars mars/notes $ ls pluto venus mars pluto $ ls pluto/notes notes notes notes

64 What does "execute" mean for directories? Gives the right to traverse the directory vlad $ ls venus venus/notes --x $ ls mars mars/notes $ ls pluto venus mars pluto $ ls pluto/notes notes notes notes

65 Change permission with chmod (change mode)

66 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final.

67 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. Everyone can read it

68 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. Everyone can read it Modify it

69 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. Everyone can read it Modify it Try to run it (which probably doesn't make sense)

70 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $

71 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ User (u) has read-write (rw)

72 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ ls -l final.grd -rw-rwxrwx 1 vlad bio :19 final. $

73 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ ls -l final.grd -rw-rwxrwx 1 vlad bio :19 final. $ chmod g=r final.grd; ls -l final.grd -rw-r--rw- 1 vlad bio :19 final. $

74 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ ls -l final.grd -rw-rwxrwx 1 vlad bio :19 final. $ chmod g=r final.grd; ls -l final.grd -rw-r--rw- 1 vlad bio :19 final. $ Use ';' to put multiple commands on a single line

75 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ ls -l final.grd -rw-rwxrwx 1 vlad bio :19 final. $ chmod g=r final.grd; ls -l final.grd -rw-r--rw- 1 vlad bio :19 final. $ chmod a= final.grd; ls -l final.grd -rw-r vlad bio :20 final.

76 Change permission with chmod (change mode) $ ls -l final.grd -rwxrwxrwx 1 vlad bio :30 final. $ chmod u=rw final.grd $ ls -l final.grd -rw-rwxrwx 1 vlad bio :19 final. $ chmod g=r final.grd; ls -l final.grd -rw-r--rw- 1 vlad bio :19 final. $ chmod a= final.grd; ls -l final.grd -rw-r vlad bio :20 final. No permissions at all

77 Again, things are different on Windows

78 Again, things are different on Windows defined by Access Control Lists (ACLs)

79 Again, things are different on Windows defined by Access Control Lists (ACLs) A list of (who, what) pairs

80 Again, things are different on Windows defined by Access Control Lists (ACLs) A list of (who, what) pairs More flexible

81 Again, things are different on Windows defined by Access Control Lists (ACLs) A list of (who, what) pairs More flexible but more complex to administer and understand

82 Again, things are different on Windows defined by Access Control Lists (ACLs) A list of (who, what) pairs More flexible but more complex to administer and understand Some flavors of Unix provide ACLs, but hardly anyone uses them

83 Create your own commands

84 Create your own commands $ cat > smallest

85 Create your own commands $ cat > smallest No input file specified, so read from keyboard

86 Create your own commands $ cat > smallest Send output to a file called smallest

87 Create your own commands $ cat > smallest wc -l *.pdb sort head -1

88 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $

89 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ Ctrl-D means "end of input" in Unix

90 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ Ctrl-D means "end of input" in Unix Ctrl-Z does the same thing in Windows

91 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $

92 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $ Give the user owner permission to run this file

93 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $./smallest

94 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $./smallest Put./ at the front to be sure of running the smallest that it's this directory

95 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $./smallest 9 methane.pdb $

96 Create your own commands $ cat > smallest wc -l *.pdb sort head -1 ^D $ chmod u+x smallest $./smallest 9 methane.pdb $ Try doing that with a desktop full of GUIs

97 created by Greg Wilson August 2010 Copyright Software Carpentry 2010 This work is licensed under the Creative Commons Attribution License See for more information.