![]() Remember that even if DAC makes a file publicly readable, a user must still have appropriate MAC clearance to see the file. A file that is set to be readable by any user on the system is called publicly readable. The individual groups can tailor their working set of files by using file permissions and Access Control Lists to share some files. ![]() On a large system with several groups, MAC labels do not provide the complete coverage desired. Complete discussion of Access Control Lists is found in the section titled “Access Control Lists.” Use the ls -D command to view the Access Control List for the file. The plus sign (+) at the end of the permission string indicates that an Access Control List is in effect for this file. The third series of spaces provides for all other users on the system and is called the public permissions. Through careful use of group read and write permissions, you can create a set of source files that are owned by one person, but any group member can work on them. All members of group grp can share a pool of files that are individually owned. Then any member of the group grp could read or execute the file, but he or she could not change it or remove it. If permissions for this file were slightly different, like this: The second series of three spaces describes permissions for the owner's group. The characters rwx indicate that the owner of the file, owner, has read, write, and execute permission on this file. The file is not a directory, so the first space is blank. Here is an example of a long listing for a file: The first series of three places in the permissions field describes the permissions for the owner of the file. For more complete information, consult the ls(1) reference page or the /usr/include/sys/stat.h file. If the file is a block special device file, a “b” appears in the space, and if the file is a character special device file, a “c” appears there. If it is a directory, a “d” appears in that space. If there is a dash in that place, the file in question is an ordinary file. However, in the leftmost place, the contents of that space describes whether the file is a file, directory, or special device file. ![]() ![]() A dash in any place means that no permission is granted and the actions associated with that permission are denied. Starting at the left, the first character is a dash. If you get a long listing of a directory, you see that the permissions field looks like this: -rw-r-r- Each character is separately significant in the permissions listing. The three relative groups are the owner of the file, the owner's group, and every other user. Execute permission allows you to run the file as a command from your shell prompt. Write permission allows you to make changes to or remove a file. Read permission allows you to look at the contents of a file. Adding the -D command line option to ls displays the Access Control List for the file or directory as well. Along with the permission information, the ls -l command lists the owners of the files and the size of the files and the date they were last modified. The command shows you more information about the files in the directory than an ordinary listing. To get a long listing, type ls -lĪt your system prompt in any directory. They are denoted as “r” for read, “w” for write, and “x” for execute in long listings of files. The three categories of permissions are read, write, and execute. Trusted IRIX/CMW divides permissions into three categories, and users into three relative groups.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |