Decoding File Permissions

Now that you know about users and groups, it's time to decode the cryptic file permissions you've seen when using the ls command. This section describes how to decipher the permissions and where they come from.

Using file permission symbols

If you remember from Chapter 3, the ls command allows you to see the file permissions for files, directories, and devices on the Linux system:

 $ ls -l
 total 68
 -rw-rw-r-- 1 rich rich   50 2010-09-13 07:49 file1.gz
 -rw-rw-r-- 1 rich rich   23 2010-09-13 07:50 file2
 -rw-rw-r-- 1 rich rich   48 2010-09-13 07:56 file3
 -rw-rw-r-- 1 rich rich   34 2010-09-13 08:59 file4
 -rwxrwxr-x 1 rich rich 4882 2010-09-18 13:58 myprog
 -rw-rw-r-- 1 rich rich  237 2010-09-18 13:58 myprog.c
 drwxrwxr-x 2 rich rich 4096 2010-09-03 15:12 test1
 drwxrwxr-x 2 rich rich 4096 2010-09-03 15:12 test2
 $

The first field in the output listing is a code that describes the permissions for the files and directories. The first character in...