Changing default access permissions

You will need to understand how to set file access permissions numerically before reading this section.

Every time you create a file or a directory, its access permissions are set to a predetermined value. This value is modified by the file-creation mode mask.

To display the value of this mask enter the command:

   umask

This will produce something like:

   077

Sometimes the 0 (zero) is omitted. The values might be different on your system.

Without the mask the system would set permissions of 666 for files and 777 for directories when first created. The values in the mask are logically ANDed with the complement of this value to give the value for access permissions for the files and directories created by you.

For example:

    777     (system value for directories)
   &700     (complement of the umask)
    ---
    700     (access permission of rwx------)

To change your default access permissions you use the command:

    umask nnn

Each "n" is a number from 0 to 7. The umask specifies which permissions bits to clear when creating files or directories.

• Tip ...
• Examples
• Summary of umask permissions

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