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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

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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)

• chmod u=rwx filename
• chmod u=rwx directoryname
• chmod -R u=rwx directoryname


• chmod g=rx filename
• chmod g=rx directoryname
• chmod -R g=rx directoryname


• chmod o=r filename
• chmod o=r directoryname
• chmod -R o=r directoryname


• chmod u=rwx,g=rx,o=r filename
• chmod u=rwx,g=rx,o=r directoryname
• chmod -R u=rwx,g=rx,o=r directoryname
• "-R" - means recursively change permissions of directories and their contents.
• chmod a=rwx filename
• "a" - for all: user/owner, group owner and all other users.

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:

• chgrp groupname filename
• chgrp -R groupname directoryname

Examples of changing user/owner:

• chown username:groupname filename
• chown -R username: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

---

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

---

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

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