Understanding Linux Permission Sets - Revision history

Casey McBride at 00:08, 13 December 2010

2010-12-13T00:08:15Z

← Older revision		Revision as of 00:08, 13 December 2010
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	The Octal Method uses numbers to indicate what permissions should be assigned to each ownership type. The Read permission has a numeric value of 4. The ~~Writer~~ permission has a numeric value of 2. The Execute permission has a numeric value of 1. If you want all three permission to be available, you add 4+2+1 and get 7. If you want all ownership types (Owner, Group, and World) to have all permissions, you would use 777. Lets look at a few examples.		The Octal Method uses numbers to indicate what permissions should be assigned to each ownership type. The Read permission has a numeric value of 4. The Write permission has a numeric value of 2. The Execute permission has a numeric value of 1. If you want all three permission to be available, you add 4+2+1 and get 7. If you want all ownership types (Owner, Group, and World) to have all permissions, you would use 777. Lets look at a few examples.

	[[File:Octal.gif]]		[[File:Octal.gif]]
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	The octal number can be used to quickly change the permissions for all the owner types.		The octal number can be used to quickly change the permissions for all the owner types.

	chmod 777 LovePoem (This would give everyone read, write and execute permission to the LovePoem		chmod 777 LovePoem (This would give everyone read, write and execute permission to the LovePoem)

	chmod 740 LovePoem (The owner has rwx permission, Group has r-- permission, World has no permission.		chmod 740 LovePoem (The owner has rwx permission, Group has r-- permission, World has no permission)


			It is possible to change the SUID, SGID, and Sticky bit using the octal representation. When changing the SUID, SGID, or Sticky bit, a 4th number is used at the beginning of the octal set.

			chmod 1777 Music (This would turn on the sticky bit and everyone would have read, write and execute permission.)

			The permission set would look like drwxrwxrwt. The "t" at the end represents the sticky bit. The "d" at the beginning identifies it as a directory.

			chmod 6770 Music (This would turn on the SUID and SGID bits. The Owner and Group would have rwx permissions. The World would have no permissions.)

			The permission set would look like drwsrws---. The "s" shows the SUID and SGID are on.

Casey McBride at 23:25, 12 December 2010

2010-12-12T23:25:34Z

← Older revision		Revision as of 23:25, 12 December 2010
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	'''Read Write Execute'''		'''Read Write Execute'''


	The three permission (read, write, and execute) have slightly different meanings depending on what object they are applied to. The two most common objects are files and directories. Below you can see how the permissions vary when applied to these two objects.		The three permission (read, write, and execute) have slightly different meanings depending on what object they are applied to. The two most common objects are files and directories. Below you can see how the permissions vary when applied to these two objects.
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	[[File:Permissions2.jpg]]		[[File:Permissions2.jpg]]



	'''Identifying Permissions'''		'''Identifying Permissions'''

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	[[File:Breakout.gif]]		[[File:Breakout.gif]]

	When the owner (Dude) looks at these permissions, he notices that the World has the "r" permission ~~and~~ can ~~therefore~~ read his LovePoem. This is not cool, Dude needs to change that permission.		When the owner (Dude) looks at these permissions, he notices that the World has the "r" permission for his LovePoem. This means the everyone can read his LovePoem. This is not cool, Dude needs to change that permission.



	'''Changing Permissions'''		'''Changing Permissions (Symbolic Method)'''

			The objects permissions can be changed using the chmod command. The symbolic method will be discussed here in basic permissions. There is also an octal method for changing permissions. That method will be discussed later in the advanced permissions. When using the symbolic method you identify which ownership group you want to change (u = Ultimate Owner, g = group, and o = others/world). Next, you use a "+" or "-" to add or remove the permission. Use r,w, or x to indicate which permission you want to add or remove. Lastly, enter the name of the file or directory you want to change.

	The objects permissions can be changed using the chmod command. The symbolic method will be discussed here in basic permissions. There is also an octal method for changing permissions. That method will be discussed later in the advanced permissions. When using the symbolic method you identify which ownership group you want to change (u = Ultimate Owner, g = group, and o = others/world). Next, you use a "+" or "-" to add or remove the permission. Identify which permission (r,w,x) you want to add or remove. Lastly, the name of the file or directory you want to change.

	So, Dude just figured out that the World has permission to read his LovePoem. He wants the World (o) to not have permission (-) to read (r) his LovePoem. So Dude enters the following chmod command to remove the permission.		So, Dude just figured out that the World has permission to read his LovePoem. He wants the World (o) to not have permission (-) to read (r) his LovePoem. So Dude enters the following chmod command to remove the permission.
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	Excellent Dude!		Excellent Dude!


	Next, Dude notices that his LinuxScript doesn't have execute permission. Every first year Linux student knows that scripts need execute permission to work. So, Dude wants all the owners (a) to have permission (+) to execute (x) the LinuxScript.		Next, Dude notices that his LinuxScript doesn't have execute permission. Every first year Linux student knows that scripts need execute permission to work. So, Dude wants all the owners (a) to have permission (+) to execute (x) the LinuxScript.
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	'''Group Permissions'''		'''Group Permissions'''


	In our current example Dude is both the owner and the group for all the files and directories. In order to allow specific groups to have access to specific things, Dude needs to add some groups and assign those groups to the objects he wants them to have access to. Dude want to add three groups: Teacher, Girlfriend, and Students. He does this with the groupadd command.		In our current example Dude is both the owner and the group for all the files and directories. In order to allow specific groups to have access to specific things, Dude needs to add some groups and assign those groups to the objects he wants them to have access to. Dude want to add three groups: Teacher, Girlfriend, and Students. He does this with the groupadd command.
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	[[File:Stickybit.gif]]		[[File:Stickybit.gif]]

	Notice that a "t" has replaced the "x" at the end of the permission string on the Music directory. So chill Dudette.		Notice that a "t" has replaced the "x" at the end of the permission string on the Music directory.

			So chill Dudette.



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	SGID (Set Group ID)
			'''SGID (Set Group ID)'''

	If the SGID bit is set, the permissions for a program or script will run at the Groups permission level. This is similar to the SUID but at the group level. If the SGID is set on a directory, any new file created in that directory will inherit the group ownership of that directory.		If the SGID bit is set, the permissions for a program or script will run at the Groups permission level. This is similar to the SUID but at the group level. If the SGID is set on a directory, any new file created in that directory will inherit the group ownership of that directory.
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	Duuuude.... Lets go surf'n now!		Duuuude.... Lets go surf'n now!



			'''Changing Permissions (The Octal Method)'''


			The Octal Method uses numbers to indicate what permissions should be assigned to each ownership type. The Read permission has a numeric value of 4. The Writer permission has a numeric value of 2. The Execute permission has a numeric value of 1. If you want all three permission to be available, you add 4+2+1 and get 7. If you want all ownership types (Owner, Group, and World) to have all permissions, you would use 777. Lets look at a few examples.

			[[File:Octal.gif]]


			The octal number can be used to quickly change the permissions for all the owner types.

			chmod 777 LovePoem (This would give everyone read, write and execute permission to the LovePoem

			chmod 740 LovePoem (The owner has rwx permission, Group has r-- permission, World has no permission.

Casey McBride at 21:53, 12 December 2010

2010-12-12T21:53:27Z

← Older revision		Revision as of 21:53, 12 December 2010
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	== Understanding Permission Sets ==		== '''Understanding Permission Sets''' ==




	It’s all about control. Who gets to do what? In Linux, every file and directory has a set of permissions assigned to it. The permissions identifies “who can do what”. There are three categories of "who" (owner, group, and world). Each of these ownership types is given or denied three permissions. The three permissions are (read, write, and execute).		It’s all about control. Who gets to do what? In Linux, every file and directory has a set of permissions assigned to it. The permissions identifies “who can do what”. There are three categories of "who" (owner, group, and world). Each of these ownership types is given or denied three permissions. The three permissions are (read, write, and execute).



	~~Basics~~
	~~Permissions (Read, Write, Execute)~~
	~~Ownership (Owner, Group, World)~~
	~~Identifying Permissions ls –l~~
	~~File Types (Normal, Directory)~~
	~~Changing permissions.(Symbolic)~~
	~~Group permissions (groupadd, chgrp)~~
	~~Advanced~~
	~~Permissions (SUID, SGID, Sticky bit)~~
	~~Ownership (Root, sudo)~~
	~~Defaults Permissions~~
	~~File Types~~
	~~Changing permissions (Octal)~~
	~~Managing permissions~~
	~~Finding special permissions~~

			== '''Basic Permissions''' ==



	'''~~Basic Permissions~~'''		'''Read Write Execute'''


	The three permission (read, write, and execute) have slightly different meanings depending on what object they are applied to. The two most common objects are files and directories. Below you can see how the permissions vary when applied to these two objects.		The three permission (read, write, and execute) have slightly different meanings depending on what object they are applied to. The two most common objects are files and directories. Below you can see how the permissions vary when applied to these two objects.
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	[[File:file_folder.gif]]		[[File:file_folder.gif]]



	'''Ownership'''		'''Ownership'''
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	[[File:Permissions2.jpg]]		[[File:Permissions2.jpg]]



	'''Identifying Permissions'''		'''Identifying Permissions'''
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	When the owner (Dude) looks at these permissions, he notices that the World has the "r" permission and can therefore read his LovePoem. This is not cool, Dude needs to change that permission.		When the owner (Dude) looks at these permissions, he notices that the World has the "r" permission and can therefore read his LovePoem. This is not cool, Dude needs to change that permission.



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	[[File:groupadd.gif]]		[[File:groupadd.gif]]


	Next, Dude adds these groups to his files and directory using the chgrp command.		Next, Dude adds these groups to his files and directory using the chgrp command.

	[[File:chgrp.gif]]		[[File:chgrp.gif]]


	Dude wants Students (g) to have permission (+) to add music files (w) to the Music directory.		Dude wants Students (g) to have permission (+) to add music files (w) to the Music directory.
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	== Advanced Permissions ==		== Advanced Permissions ==

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	Although the Sticky bit has had different uses over time. Currently it is used to protect files from being deleted by non-owners. If the sticky bit is used on a directory the files in that directory can only be deleted by the owner of the file, the owner of the directory, or root.		Although the Sticky bit has had different uses over time. Currently it is used to protect files from being deleted by non-owners. If the sticky bit is used on a directory the files in that directory can only be deleted by the owner of the file, the owner of the directory, or root.


	So Dude has added three friend to the Student Group (Sand, Surf, and Dudette). All three friends have been adding music to the Music directory. But Dudette doesn't like the Beach Boys, so she has been deleting some of Surf's Beach Boy songs. To prevent Dudette from continueing to delete other peoples music. Dude uses the chmod command to add (+) the Sitcky bit (t) to the Music directory.		So Dude has added three friend to the Student Group (Sand, Surf, and Dudette). All three friends have been adding music to the Music directory. But Dudette doesn't like the Beach Boys, so she has been deleting some of Surf's Beach Boy songs. To prevent Dudette from continueing to delete other peoples music. Dude uses the chmod command to add (+) the Sitcky bit (t) to the Music directory.
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	Notice that a "t" has replaced the "x" at the end of the permission string on the Music directory. So chill Dudette.		Notice that a "t" has replaced the "x" at the end of the permission string on the Music directory. So chill Dudette.



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	[[File:SurfsUpScript.gif]]		[[File:SurfsUpScript.gif]]

	Notice the "rws" has replaced "rwx" in the owners permission set. Now when anyone runs the SurfUpScript, it will run with the owner's permissions. Surf'n Safari Dude!		Notice the "rws" has replaced "rwx" in the owners permission set. Now when anyone runs the SurfUpScript, it will run with the owner's permissions.

			Surf'n Safari Dude!



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	If the SGID bit is set, the permissions for a program or script will run at the Groups permission level. This is similar to the SUID but at the group level. If the SGID is set on a directory, any new file created in that directory will inherit the group ownership of that directory.		If the SGID bit is set, the permissions for a program or script will run at the Groups permission level. This is similar to the SUID but at the group level. If the SGID is set on a directory, any new file created in that directory will inherit the group ownership of that directory.


	Dude goes into the music directory and sees that his friends (Surf, Sand, and Dudette) have all added a song in the Music Directory. By default the Group for each song is the same as the owner who created it.		Dude goes into the music directory and sees that his friends (Surf, Sand, and Dudette) have all added a song in the Music Directory. By default the Group for each song is the same as the owner who created it.

	[[File:Music.gif]]		[[File:Music.gif]]


	Dude wants the default group to be Students when anyone adds a song to the Music folder. Dude enables the SGID bit to accomplish this. Dude adds (+) the SGID (s) to the Music directory that he is currently in (../Music).		Dude wants the default group to be Students when anyone adds a song to the Music folder. Dude enables the SGID bit to accomplish this. Dude adds (+) the SGID (s) to the Music directory that he is currently in (../Music).
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	Because Dude is in the Music directory, it shows up as the first line with the name (.). You can see that the group permission has changed from rwx to rws. The (s) indicates that the SGID is enabled. So now when anyone adds a song to the Music folder, the default group will be Students.		Because Dude is in the Music directory, it shows up as the first line with the name (.). You can see that the group permission has changed from rwx to rws. The (s) indicates that the SGID is enabled. So now when anyone adds a song to the Music folder, the default group will be Students.


	Surf, Sand, and Dudette each added a new song to the music folder:		Surf, Sand, and Dudette each added a new song to the music folder:

	[[File:Music2.gif]]		[[File:Music2.gif]]


	Dude sees that the new songs are getting the group Students but he wants all the existing songs in the folder to have the group Students also. Dude can use the chgrp command with the recursive option (-R) to accomplish this.		Dude sees that the new songs are getting the group Students but he wants all the existing songs in the folder to have the group Students also. Dude can use the chgrp command with the recursive option (-R) to accomplish this.

Casey McBride at 21:38, 12 December 2010

2010-12-12T21:38:36Z

← Older revision		Revision as of 21:38, 12 December 2010
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	Dude goes into the music directory and sees that his friends (Surf, Sand, and Dudette) have all added a song in the Music Directory. By default the Group for each song is the same as the owner who created it.		Dude goes into the music directory and sees that his friends (Surf, Sand, and Dudette) have all added a song in the Music Directory. By default the Group for each song is the same as the owner who created it.

	[[File:Music,gif]]		[[File:Music.gif]]

	Dude wants the default group to be Students when anyone adds a song to the Music folder. Dude enables the SGID bit to accomplish this. Dude adds (+) the SGID (s) to the Music directory that he is currently in (../Music).		Dude wants the default group to be Students when anyone adds a song to the Music folder. Dude enables the SGID bit to accomplish this. Dude adds (+) the SGID (s) to the Music directory that he is currently in (../Music).

Casey McBride at 21:32, 12 December 2010

2010-12-12T21:32:11Z

← Older revision		Revision as of 21:32, 12 December 2010
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	'''Identifying Permissions'''		'''Identifying Permissions'''

	~~You~~ find out what permissions are being applied to the current objects ~~with~~ the ls -l command. ~~The permission string is at the beginning of the object.~~		To find out what permissions are being applied to the current objects, you use the ls -l command.

	Example:		Example:
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	[[File:ls_-l.gif]]		[[File:ls_-l.gif]]

	The first digit in each line of output identifies the type of object ~~it is~~. The two most common types are - and d . Type "-" represents a normal data file, like a text file, music file, graphics file, etc. The "d" represents a directory. The next nine characters are the permission sets.		The first digit in each line of output identifies the type of object. The two most common types are "-" and "d". Type "-" represents a normal data file, like a text file, music file, graphics file, etc. The "d" represents a directory. The next nine characters are the three permission sets.

	[[File:Breakout.gif]]		[[File:Breakout.gif]]

	When the owner (Dude) looks at these permissions he notices that the World has the "r" permission and can therefore read his LovePoem. This is not cool, Dude needs to change that permission.		When the owner (Dude) looks at these permissions, he notices that the World has the "r" permission and can therefore read his LovePoem. This is not cool, Dude needs to change that permission.


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	Next, Dude adds these groups to his files and directory using the chgrp command.		Next, Dude adds these groups to his files and directory using the chgrp command.

	[[File:~~chrgp~~.gif]]		[[File:chgrp.gif]]

	Dude wants Students (g) to have permission (+) to add music files (w) to the Music directory.		Dude wants Students (g) to have permission (+) to add music files (w) to the Music directory.
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	'''Sticky bit (mainly for directories)'''		'''Sticky bit - mainly for directories'''

	Although the Sticky bit has had different uses over time. Currently it is used to protect files from being deleted by non-owners. If the sticky bit is used on a directory the files in that directory can only be deleted by the owner of the file, the owner of the directory, or root.		Although the Sticky bit has had different uses over time. Currently it is used to protect files from being deleted by non-owners. If the sticky bit is used on a directory the files in that directory can only be deleted by the owner of the file, the owner of the directory, or root.
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	[[File:Stickybit.gif]]		[[File:Stickybit.gif]]

	Notice that a "t" has replaced the "x" at the end of the permission string on the Music Directory. So ~~chill~~ Dudette.		Notice that a "t" has replaced the "x" at the end of the permission string on the Music directory. So chill Dudette.


			'''SUID (Set User ID) - Mainly used on scripts'''

			If the SUID bit is set, the script will run with the owner's permissions even when it is run by another user.


			Dude wrote the SurfsUpScipt. The SurfsUpSript randomly chooses an excuse from the ExcuseDatabase and sends an ExcuseEmail to all his teachers, explaining why he will miss class today. Dude's girlfriend (Dudette) wants to use the script to send her teachers the ExcuseEmail but it fails with permission errors. The script needs administrative permissions to run. There's no way Dude is going to give Dudette administrative permissions on the system; she would delete Dudette2, 3, and 4 from Dude's database. Dude needs to add (+) SUID permission (s) to the SurfsUpScript. That way, when Dudette runs the SurfUpScipt, the permissions will automatically be at Dude's (the owner's) permission level.

			[[File:SurfsUpScript.gif]]

			Notice the "rws" has replaced "rwx" in the owners permission set. Now when anyone runs the SurfUpScript, it will run with the owner's permissions. Surf'n Safari Dude!


			SGID (Set Group ID)

			If the SGID bit is set, the permissions for a program or script will run at the Groups permission level. This is similar to the SUID but at the group level. If the SGID is set on a directory, any new file created in that directory will inherit the group ownership of that directory.

			Dude goes into the music directory and sees that his friends (Surf, Sand, and Dudette) have all added a song in the Music Directory. By default the Group for each song is the same as the owner who created it.

			[[File:Music,gif]]

			Dude wants the default group to be Students when anyone adds a song to the Music folder. Dude enables the SGID bit to accomplish this. Dude adds (+) the SGID (s) to the Music directory that he is currently in (../Music).

			[[File:GUID.gif]]

			Because Dude is in the Music directory, it shows up as the first line with the name (.). You can see that the group permission has changed from rwx to rws. The (s) indicates that the SGID is enabled. So now when anyone adds a song to the Music folder, the default group will be Students.

			Surf, Sand, and Dudette each added a new song to the music folder:

			[[File:Music2.gif]]

			Dude sees that the new songs are getting the group Students but he wants all the existing songs in the folder to have the group Students also. Dude can use the chgrp command with the recursive option (-R) to accomplish this.

			[[File:Music3.gif]]

			Duuuude.... Lets go surf'n now!

Casey McBride at 20:31, 12 December 2010

2010-12-12T20:31:04Z

@@ Line 41: / Line 41: @@
 Permission Sets provide security to your files and directories.  You can either give or not give permissions.  Permission Sets are made up of three triplets, each of which contains three characters.  These three characters are "r" for read, "w" for write, and "x" for execute.  A dash taking the place of any of those characters in the triplet means that the permission is denied.  The first set of triplets represents the owner's(user's) permissions.  The second set of triplets represents the group's permissions.  The third set of triplets dictate the permissions for everyone else.
-[[File:Permissions.jpg]]
+[[File:Permissions2.jpg]]
-There are actually ten positions in a Permission Set.  The tenth position is in
+'''Identifying Permissions'''
-front of the rest.  It tells you the type of file that it is.  It can be a dash(regular
-file), a "b"(block device), a "c"(character device), a "d"(directory), an "l"(link), or
+You find out what permissions are being applied to the current objects with the ls -l command.  The permission string is at the beginning of the object.
-many others.
-[[File:Look_of_permissions.jpg]]
+== Advanced Permissions ==

Casey McBride at 19:21, 12 December 2010

2010-12-12T19:21:33Z

← Older revision		Revision as of 19:21, 12 December 2010
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	Permission Sets provide security to your files and directories. You can either give or not give permissions. Permission Sets are made up of three triplets, each of which contains three characters. These three characters are "r" for read, "w" for write, and "x" for execute. A dash taking the place of any of those characters in the triplet means that the permission is denied. The first set of triplets represents the owner's(user's) permissions. The second set of triplets represents the group's permissions. The third set of triplets dictate the permissions for everyone else.		Permission Sets provide security to your files and directories. You can either give or not give permissions. Permission Sets are made up of three triplets, each of which contains three characters. These three characters are "r" for read, "w" for write, and "x" for execute. A dash taking the place of any of those characters in the triplet means that the permission is denied. The first set of triplets represents the owner's(user's) permissions. The second set of triplets represents the group's permissions. The third set of triplets dictate the permissions for everyone else.

	[[File:~~Permissions2~~.jpg]]		[[File:Permissions.jpg]]

	There are actually ten positions in a Permission Set. The tenth position is in		There are actually ten positions in a Permission Set. The tenth position is in

Casey McBride at 19:16, 12 December 2010

2010-12-12T19:16:44Z

← Older revision		Revision as of 19:16, 12 December 2010
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	Permission Sets provide security to your files and directories. You can either give or not give permissions. Permission Sets are made up of three triplets, each of which contains three characters. These three characters are "r" for read, "w" for write, and "x" for execute. A dash taking the place of any of those characters in the triplet means that the permission is denied. The first set of triplets represents the owner's(user's) permissions. The second set of triplets represents the group's permissions. The third set of triplets dictate the permissions for everyone else.		Permission Sets provide security to your files and directories. You can either give or not give permissions. Permission Sets are made up of three triplets, each of which contains three characters. These three characters are "r" for read, "w" for write, and "x" for execute. A dash taking the place of any of those characters in the triplet means that the permission is denied. The first set of triplets represents the owner's(user's) permissions. The second set of triplets represents the group's permissions. The third set of triplets dictate the permissions for everyone else.

	[[File:~~Permissions~~.jpg]]		[[File:Permissions2.jpg]]

	There are actually ten positions in a Permission Set. The tenth position is in		There are actually ten positions in a Permission Set. The tenth position is in

Casey McBride at 19:14, 12 December 2010

2010-12-12T19:14:41Z

← Older revision		Revision as of 19:14, 12 December 2010
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	== Understanding Permission Sets ==		== Understanding Permission Sets ==



			It’s all about control. Who gets to do what? In Linux, every file and directory has a set of permissions assigned to it. The permissions identifies “who can do what”. There are three categories of "who" (owner, group, and world). Each of these ownership types is given or denied three permissions. The three permissions are (read, write, and execute).


	It’s all about control. Who gets to do what? In Linux, every file and directory has a set of permissions assigned to it. The permissions identifies “who can do what”. There are three categories of "who" (owner, group, and world). Each of these ownership types is given or denied three permissions. The three permissions are (read, write, and execute).

	Basics		Basics
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	Finding special permissions		Finding special permissions

	Basic Permissions (~~Read~~, ~~Write~~, ~~Execute~~)

			'''Basic Permissions'''

			The three permission (read, write, and execute) have slightly different meanings depending on what object they are applied to. The two most common objects are files and directories. Below you can see how the permissions vary when applied to these two objects.

			[[File:file_folder.gif]]


	The ~~permissions have slightly different meanings depending on what~~ object ~~they are applied to~~. ~~The two most common objects are files and directories~~. ~~Below you can see how~~ the ~~permissions change when applied~~ to ~~a file or directory~~.		'''Ownership'''

	~~[[File:FileVSfolder~~.~~pdf]]~~		There are three types of ownership:
			*Owner - this is the ultimate user. The creator or current owner of the object. Also known as user.
			*Group - this is an assigned membership. You need to be a member of the group to get it.
			*World - this is everyone else. All the other guys. Also known as other.

	Permission Sets provide security to your files and directories ~~so you~~ can either		Permission Sets provide security to your files and directories. You can either give or not give permissions. Permission Sets are made up of three triplets, each of which contains three characters. These three characters are "r" for read, "w" for write, and "x" for execute. A dash taking the place of any of those characters in the triplet means that the permission is denied. The first set of triplets represents the owner's(user's) permissions. The second set of triplets represents the group's permissions. The third set of triplets dictate the permissions for everyone else.
	give, or not give~~, permission to users to read, modify, or run those files and~~
	~~directories~~. Permission Sets are made up of three triplets, each of which contains
	three characters. These three characters are "R" ~~meaning~~ read, "W" ~~meaning~~ write,
	and "X" ~~meaning~~ execute. A dash taking the place of any of those characters in the
	triplet means that the ~~owner, group, or other user(neither the owner nor included in~~
	~~a group),~~ is denied ~~that certain permission~~. The first set of triplets ~~dictate~~ the
	~~permissions to the files owners~~(~~users~~). The second set of triplets ~~dictate~~ the
	permissions ~~for the group assigned to the file~~. The third set of triplets dictate
	the permissions for everyone else.

	[[File:Permissions.jpg]]		[[File:Permissions.jpg]]

Casey McBride at 16:19, 12 December 2010

2010-12-12T16:19:32Z

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-'''Understanding Permission Sets'''
 It’s all about control.  Who gets to do what?  In Linux, every file and directory has a set of permissions assigned to it.  The permissions identifies “who can do what”.  There are three categories of "who" (owner, group, and world).  Each of these ownership types is given or denied three permissions.  The three permissions are (read, write, and execute).
 Permission Sets provide security to your files and directories so you can either
 give, or not give, permission to users to read, modify, or run those files and