ls -l outputs a 10 symbol UNIX string of information popularly known as permission string. e.g.
-rw-rw-r-- 1 userName groupName 13200650 Dec 13 21:23 fileName
The first character of permission string or mode string, known as the file descriptor, indicates the file type and the remaining nine taken in groups of three indicate the permissions for the file concerned, where:
- the first group of three characters (after the first character among the 10) indicate owner's permissions,
- the second group of three designate permissions for the group,
- the last group of three designate permissions for others (or the world).
Here, in above example the first character/symbol the "-" indicates a normal file.
While in the following examples,
crw-rw-rw- 1 root root 1, 3 Dec 29 20:58 /dev/null
crw-rw-rw- 1 root root 1, 5 Jan 13 20:56 /dev/zero
the permission strings' first character is "c" and like stated above, it is a file-type indicator which indicates a character device.
Apart from the
c some other file descriptors are:
d -> directory
l -> symbolic link
s -> Unix socket
b -> block device
p -> pipeline
D -> Door