Thus, an application must explicitly allow sharing when it opens a file; otherwise it has exclusive read, write, and delete access to the file until closed other types of access, such as those to retrieve the attributes of a file are allowed. For a file opened with shared access, applications may then use byte-range locking to control access to specific regions of the file. Such byte-range locks specify a region of the file offset and length and the type of lock shared or exclusive.
There are two permissions, one for reading and one for writing, and they are managed independently. This is not a bug since the documented behavior coincides with the actual behavior and there is no good reason to require a different behavior.
Having write permissions without read permissions doesn't make much sense for regular files. It does make sense for various special files. Some systems allow append-only files. This is useful for log files, for example.
It can make sense to allow many users to create log entries, but not to allow them to erase or overwrite existing entries hence: A program may be allowed to write to a named pipe without being allowed to read from it. Some devices are write-only.
For example, a sound output device connected to a loudspeaker but no microphone should have write permission but no read permission. There are various special filesystems where reading or writing to a file has an immediate effect instead of retrieving or adding data to storage.
If that command doesn't provide any feedback, the special file is made write-only.Digital Forensics with Open Source Tools is the definitive book on investigating and analyzing computer systems and media using open source tools.
The book is a technical procedural guide, and explains the use of open source tools on Mac, Linux and Windows systems as a platform . To best share with multiple users who should be able to write in /var/www, it should be assigned a common group.
For example the default group for web content on Ubuntu and Debian is www-data. Make sure all the users who need write access to /var/www are in this group. There are four categories (System, Owner, Group, and World) and four types of access permissions (Read, Write, Execute and Delete).
The categories are not mutually disjoint: World includes Group which in turn includes Owner. func Getegid ¶ func Getegid() int Getegid returns the numeric effective group id of the caller. On Windows, it returns func Getenv ¶ func Getenv(key string) string. Getenv retrieves the value of the environment variable named by the key.
Using ACL to Give Read/Write Access to User on Directory Important: To use this method, ensure that your Linux filesystem type (such as Ext3 and Ext4, NTFS, BTRFS) support ACLs. 1. Full read/write access to NTFS and HFS+ volumes! Microsoft NTFS for Linux by Paragon Software is a unique combination of drivers for the NTFS and HFS+ file systems accessible from a Linux environment.