Instructions for setting group-writable permissions

Last Updated 2019-05-31 by Adam Lu

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Individual Files

• To change a file’s permission to group writable, use one of the following:

  # Change a directory or file that you created to be group writable
  chmod g+w [fileOrDirPath]
    
  # Change a directory or file that someone else created to be group writable
  sudo chmod g+w [fileOrDirPath]
    
  # Change a directory you created and all files within it to be group writable
  chmod -R g+w [dirPath]
    
  # Change a directory someone else created and all files within it to be group writable
  sudo chmod -R g+w [dirPath]
    
  # An alias Adam made for all users on fishfish
  chmodRgw [fileOrDirPath]
  

  Caution: It is not advisable to change permission recursively to 775, because that would make a lot of files erroneously executable. By default, files are created with the permissions 644 and directories are created with the permissions 755. Using g+w would change file permissions to 664 and directory permissions to 775, respectively, as desired.

Global settings

• For Unix in general, add this line to either the file ~/.bashrc (to set this for yourself only) or the file /etc/bash.bashrc (to set this for all users on the machine):

  umask 002
  

  This means that write permissions are removed for everyone else but not for group. In comparison, the default umask value is 022, which would remove write permissions for both group and everyone else.

• For Samba, edit the Samba configuration file /etc/samba/smb.conf:

  • Under [global] (the Global settings section), add this parameter

    inherit permissions = yes
    

    This is a tip from a reply here.

  • Under each individual file share (e.g., [shareX]), add the parameters:

    directory mode = 775
    create mode = 775
    

    Note that you can also do this on Webmin by clicking on the share name, then File Permissions, then change New Unix file mode to 775 and New Unix directory mode to 775 (these are masks).