namespaces.7: Include manual page references in the summary table of namespace types

Make the page more compact by removing the stub subsections that
list the manual pages for the namespace types. And while we're
here, add an explanation of the table columns.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/namespaces.7 b/man7/namespaces.7
index 0f0665b7a80447ba50cc0834444431b85cb62772..76eece8b05832c547a58db7cc5154646d75d0929 100644 (file)
--- a/man7/namespaces.7
+++ b/man7/namespaces.7
@@ -35,24 +35,45 @@ Changes to the global resource are visible to other processes
 that are members of the namespace, but are invisible to other processes.
 One use of namespaces is to implement containers.
 .PP
-Linux provides the following namespaces:
-.TS
-lB lB lB
-l lB l.
-Namespace      Constant        Isolates
-Cgroup CLONE_NEWCGROUP Cgroup root directory
-IPC    CLONE_NEWIPC    System V IPC, POSIX message queues
-Network        CLONE_NEWNET    Network devices, stacks, ports, etc.
-Mount  CLONE_NEWNS     Mount points
-PID    CLONE_NEWPID    Process IDs
-User   CLONE_NEWUSER   User and group IDs
-UTS    CLONE_NEWUTS    Hostname and NIS domain name
-.TE
-.PP
-This page describes the various namespaces and the associated
+This page provides pointers to information on the various namespace types,
+describes the associated
 .I /proc
 files, and summarizes the APIs for working with namespaces.
 .\"
+.SS Namespace types
+.PP
+The following table shows the namespace types available on Linux.
+The second column of the table shows the flag value that is used to specify
+the namespace type in various APIs.
+The third column identifies the manual page that provides details
+on the namespace type.
+The last column is a summary of the resources that are isolated by
+the namespace type.
+.TS
+lB lB lB lB
+l1 lB1 l1 l.
+Namespace      Flag    Page    Isolates
+Cgroup CLONE_NEWCGROUP \fBcgroup_namespaces\fP(7)      Cgroup root directory
+IPC    CLONE_NEWIPC    \fBipc_namespaces\fP(7) T{
+System V IPC,
+.br
+POSIX message queues
+T}
+Network        CLONE_NEWNET    \fBnetwork_namespaces\fP(7)     T{
+Network devices,
+.br
+stacks, ports, etc.
+T}
+Mount  CLONE_NEWNS     \fBmount_namespaces\fP(7)       Mount points
+PID    CLONE_NEWPID    \fBpid_namespaces\fP(7) Process IDs
+User   CLONE_NEWUSER   \fBuser_namespaces\fP(7)        User and group IDs
+UTS    CLONE_NEWUTS    \fButs_namespaces\fP(7) T{
+Hostname and NIS
+.br
+domain name
+T}
+.TE
+.\"
 .\" ==================== The namespaces API ====================
 .\"
 .SS The namespaces API
@@ -319,49 +340,6 @@ for the creator UID in the ancestor namespace is not exceeded.
 The aforementioned point ensures that creating a new user namespace
 cannot be used as a means to escape the limits in force
 in the current user namespace.
-.RE
-.\"
-.\" ==================== Cgroup namespaces ====================
-.\"
-.SS Cgroup namespaces (CLONE_NEWCGROUP)
-See
-.BR cgroup_namespaces (7).
-.\"
-.\" ==================== IPC namespaces ====================
-.\"
-.SS IPC namespaces (CLONE_NEWIPC)
-See
-.BR ipc_namespaces (7).
-.\"
-.\" ==================== Network namespaces ====================
-.\"
-.SS Network namespaces (CLONE_NEWNET)
-See
-.BR network_namespaces (7).
-.\"
-.\" ==================== Mount namespaces ====================
-.\"
-.SS Mount namespaces (CLONE_NEWNS)
-See
-.BR mount_namespaces (7).
-.\"
-.\" ==================== PID namespaces ====================
-.\"
-.SS PID namespaces (CLONE_NEWPID)
-See
-.BR pid_namespaces (7).
-.\"
-.\" ==================== User namespaces ====================
-.\"
-.SS User namespaces (CLONE_NEWUSER)
-See
-.BR user_namespaces (7).
-.\"
-.\" ==================== UTS namespaces ====================
-.\"
-.SS UTS namespaces (CLONE_NEWUTS)
-See
-.BR uts_namespaces (7).
 .\"
 .SS Namespace lifetime
 Absent any other factors,