UNIX permision flags

They are grouped in thre basic sets

• {u}User who created the file.
• {g}Group group to which the file belongs
• {o}Other access for anyone else.

The ls -l or find . -ls commands display the permision bits for files as

• File type
  • {-} Regular file
  • {d} Directory
  • {l} Symbolic link
• Three characters indecating user permison bits
• Three characters indecating group permison bits
• Three characters indecating other permison bits

There are 3 basic access rights,and one extended that can be set on each "file" though there exact meaning depends on whetherthey are applied to a regular file or a directory.

• Regular files
  • {r}Read
  • {w}Write,update,truncate
  • {x}execute
• Directories
• {r}Read
• {w}Create/Delete files
• {x}Scan for subdirectories

  Extended rights

  {s}/{S} Sticky/Set id bit can be applied to user, group, or other set though its use/meaning differs.

  Regular file user/group set

  Only valid for comiled native code. Programme will be executed with efecitive UID/GID set to that of the file the rest of the group membership will be inherited from the user who is running the program.

  Directory group bit

  Afects file creation, as long as the user has the group of the directory as one of the groups in there group set all files they create in this directory wil be created as the same group as the directory, ratherthan being created as the user primary group {Normaly staff}.

  Directory other bit

  If set only the owner of the directory or the owners of the files within may delete files