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Permissions are
broken up into four groups, each group is comprised of bits (a binary
1 or 0) that actually set the permissions and control who can read,
write and execute files or directories.The
permissions on a file might look like this:
The first bit indicates
whether this is a file (-) or directory (d)
Bits 2,3,4 display
owner permissions. Linux understands this concept of ownership-
whoever creates a file owns it. This set of permissions defines
what the owner (or user) of the file or directory can do with it.
Bits 5,6,7 display
group permissions. Administrators create and assign users to groups,
a convenient way of granting identical permissions to multiple users
at once. This is handy when several people are working on a project
together and need access to the same files. This grouping of permissions
is applied to users that are in the same group as the owner.
Bits 8,9,10
display other permissions. These permissions are applied to users
that are not covered by the rest of the permissions. This is also
referred to as public or world permissions.
The following
table describes the permission groupings:
|
Name
of bit or bit set
|
Indication
|
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file
type (first bit)
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- indicates that this is a file, d indicates directory
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owner
permissions (next three bits)
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shows
the type of access the owner of the file has.
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group
permissions (second set of three bits)
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shows
the type of access users in the same group have.
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other
permissions (last set of bits)
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shows the permissions everyone else has.
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Note:
A dash in the owner, group or other permissions indicates no permission.
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