View source for Top Chmod Command Examples for Beginners

==Top Chmod Command Examples for Beginners==

Let us review how to use symbolic representation with chmod.

Following are the symbolic representation of three different roles:

u is for user,
g is for group,
and o is for others.
Following are the symbolic representation of three different permissions:

r is for read permission,
w is for write permission,
x is for execute permission.
Following are few examples on how to use the symbolic representation on chmod.

===Add single permission to a file/directory===
Changing permission to a single set. + symbol means adding permission. For example, do the following to give execute permission for the user irrespective of anything else:

 $ chmod u+x filename
===Add multiple permission to a file/directory===
Use comma to separate the multiple permission sets as shown below.

 $ chmod u+r,g+x filename
===Remove permission from a file/directory===
Following example removes read and write permission for the user.

 $ chmod u-rx filename
===Change permission for all roles on a file/directory===
Following example assigns execute privilege to user, group and others (basically anybody can execute this file).

 $ chmod a+x filename
===Make permission for a file same as another file (using reference)===
If you want to change a file permission same as another file, use the reference option as shown below. In this example, file2’s permission will be set exactly same as file1’s permission.

 $ chmod --reference=file1 file2
===Apply the permission to all the files under a directory recursively===
Use option -R to change the permission recursively as shown below.

 $ chmod -R 755 directory-name/
===Change execute permission only on the directories (files are not affected)===
On a particular directory if you have multiple sub-directories and files, the following command will assign execute permission only to all the sub-directories in the current directory (not the files in the current directory).

 $ chmod u+X *
Note: If the files has execute permission already for either the group or others, the above command will assign the execute permission to the user