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ADVANCED TECHNICAL RESOURCES

UNIX, LINUX & OS X File Permissions

To view permission information for all files and directories inside the current working directory, open a new terminal and type: ls -l

Here is an example of the output:
drwxr-xr-x 6 user group 204 Dec 30 06:37 images
-rw-r--r-- 1 user group 5754 May 20 2005 index.html
-rw-r--r-- 1 user group 9482 Jan 16 16:29 mypage.html

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To view permission information for a particular file (for example:myfile.txt) type: ls -l myfile.txt

Here is an example of the output:
-rw-r--r-- 1 user group 9482 Jan 16 16:29 myfile.txt

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Here is a quick reference and diagram of what "-rwxrw-r--" means:
"r" means: read permission
"w" means: write permission
"x" means: execute permission

Type	Description
-	FIle type: " - " means a file. " d " means a directory
rwx	Read, write and execute permissions for members of the owner of the file
rw-	Read, write and execute permissions for members of the group owning the file
r--	Read, write and execute permissions for all other users

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Changing file and folder permissions

Use the following commands to change file or folder permissions:
chmod (change file modes)
chown (change file owner)
chgrp (change file group owner)

The following letters represent
" u " - user/owner
" g " - group owner
" o " - all other users
" a " - for all: user/owner, group owner and all other users
" r " - read permission
" w " - write permission
" x " - execute permission

Examples of replacing and setting new permissions

(Note: Do not use space between any of the statements.
Example DO NOT TYPE: u = rwx)

Examples of adding or taking away permissions from the current permissions

# chmod u+w filename
# chmod u+w directoryname
# chmod -R u+w directoryname

# chmod g+w filename
# chmod g+w directoryname
# chmod -R g+w directoryname

# chmod o-r filename
# chmod o-r directoryname
# chmod -R o-r directoryname

Modifying multiple permissions examples:

* chmod u+w,g+x,o-r filename
* chmod ug+rwx filename
* chmod ugo+rwx filename
* chmod u+w,g+x,o-r directoryname
* chmod ug+rwx directoryname
* chmod ugo+rwx directoryname
* chmod -R u+w,g+x,o-r directoryname
* chmod -R ug+w,o-r directoryname
* chmod -R ugo+rwx directoryname
* "-R" - means recursively change permissions of directories and their contents.

Examples of changing user/owner:

* chown username filename
* chown -R username directoryname

Examples of changing user/owner:

* chown username filename
* chown -R username directoryname

Examples of changing user/owner:

* chgrp groupname filename
* chgrp -R groupname directoryname

"-R" - means recursively change permissions of directories and their contents.

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Here is some more examples:
chmod u=rwx,g=rw,o=rx myfile.txt
Now view the result:
ls -l myfile.txt
-rwxrw-r-x 1 user group 9482 Jan 16 16:29 myfile.txt

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chmod -R u=rwx,g=rx,o=r directoryname
Now view the result:
ls -l directoryname
drwxr-xr-- 6 user group 204 Dec 30 06:37 images
-rwxr-xr-- 1 user group 5754 May 20 2005 index.html
-rwxr-xr-- 1 user group 9482 Jan 16 16:29 mypage.html

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chown -R www directoryname
Now view the result:
ls -l directoryname
drwxr-xr-- 6 www group 204 Dec 30 06:37 images
-rwxr-xr-- 1 www group 5754 May 20 2005 index.html
-rwxr-xr-- 1 www group 9482 Jan 16 16:29 mypage.html

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chgrp -R www directoryname
Now view the result:
ls -l directoryname
drwxr-xr-- 6 www www 204 Dec 30 06:37 images
-rwxr-xr-- 1 www www 5754 May 20 2005 index.html
-rwxr-xr-- 1 www www 9482 Jan 16 16:29 mypage.html

To read additional information on Linux common commands and linux permissions, user the below resources:
File Systems Comparison - Maximum Characters
UNIX & OS X Commands References
UNIX & OS X File Permissions
More Unix Commands
Unix/Linux IP & Firewall Configuration, etc.
MySQL Administration
Linux rsync
Linux Intalling and Updating with YUM
Linux backing up with Cron and rsync
MySQL Backing Up using MySQLDump and rsync