Introduction Show
When creating a new file or directory, Linux applies the default set of permissions. The In this tutorial, you will learn what umask is, how it works, and how to use it to set up file and directory permissions for individual users or groups. Prerequisites
Umask OverviewThe term umask refers to two things: 1. The Linux 2. A user-defined permissions ‘mask’. A user can choose how to restrict permissions by using a permissions mask. A
permission mask interacts with the default system permissions and changes them. The How Does Umask Work?The There are three categories of permissions for every file and folder in Linux:
Use the following command to review permissions for the home folder:
Each line of the output starts with a 10-character string detailing permissions. Breaking down the highlighted entry, this string consists of the following elements:
The umask Command SyntaxUsing the The
Where:
Symbolic and Numeric umask ValuesAs we mentioned in the example above, umask can be displayed as a numeric (octal) or symbolic value. A mask can have the following numeric, and the corresponding symbolic, values:
How to Calculate Umask ValuesLinux uses the following default mask and permission values:
This shows us that the final permission value is the result of subtracting the umask value form the default permission value (777 or 666). For example, if you want to change the folder permission value from 777 (read, write, and execute for all) to 444 (read for all), you need to apply a umask value of 333, since:
How to Set and Update the Default Umask ValueUse the following syntax to apply a new
Where:
Setting Up a Symbolic Umask ValueSet a new umask value by using symbolic values with the following syntax:
Where:
Note: Never use space after comas when setting up a symbolic mask value. There are also other operators you can use:
Setting Up a Numeric Umask ValueOnce you calculate the required umask numeric value, set it up by using:
Where:
Difference Between umask and chmodThe chmod command in Linux works in a similar way to the The difference between Conclusion After following this tutorial, you should be able to review and change umask using symbolic or numeric values. Make sure you also take a look at our Linux command cheat sheet for more commonly used Linux commands. Which of the following umask settings does not allow execute permission to be set by default on directory files?With a umask value of 112, what is the default permission assigned to newly created regular file?
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. What does umask 007 mean for a directory?With umask 007, directories will have permission 770 and new files will have permission 660. The net effect is that new DataStage files and directories (primarily files created for new jobs in the project directories) will no longer be public readable.
What does umask 022 mean?A umask of 022 allows only you to write data, but anyone can read data. A umask of 077 is good for a completely private system. No other user can read or write your data if umask is set to 077. A umask of 002 is good when you share data with other users in the same group.
What does umask 777 mean?umask 777. disallow read, write, and execute permission for all (probably not useful because even owner cannot read files created with this mask!) umask 000. allow read, write, and execute permission for all (potential security risk)
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