Factor xunshare/xnsenter into lib.sh and use it in topo-square as well

.gitignore

 A
 B
 C
+D

namespace_demo/lib.sh

+# lib.sh is library of common shell functions for topo-*
+
+# `xunshare <dir> ...`  -- unshare net/mount/... namespaces to be referenced by dir
+xunshare() {
+    ref=$1
+    shift
+    rm -rf "$ref"
+    mkdir "$ref"
+    touch $ref/mnt $ref/net
+    unshare --mount=$ref/mnt --net=$ref/net "$@"
+}
+
+# `xnsenter <dir> ...`  -- nsenter net/mount/... namespaces to be referenced by dir
+xnsenter() {
+    ref=$1
+    shift
+    nsenter --mount=$ref/mnt --net=$ref/net --wd=. "$@"
+}

namespace_demo/topo-B-A-C.sh

@@ -13,25 +13,9 @@
 #
 # Based on https://github.com/troglobit/smcroute/tree/master/test
 
-rm -rf A B C
-mkdir A B C
-PID=$$
-
-# `xunshare <dir> ...`  -- unshare net/mount/... namespaces to be referenced by dir
-xunshare() {
-    ref=$1
-    shift
-    touch $ref/mnt $ref/net
-    unshare --mount=$ref/mnt --net=$ref/net "$@"
-}
-
-# `xnsenter <dir> ...`  -- nsenter net/mount/... namespaces to be referenced by dir
-xnsenter() {
-    ref=$1
-    shift
-    nsenter --mount=$ref/mnt --net=$ref/net --wd=. "$@"
-}
+. lib.sh
 
+PID=$$
 
 # B-br0-A
 xunshare B -- ip link set lo up

namespace_demo/topo-square.sh

@@ -19,25 +19,25 @@
 #
 #
 # should be run under unshare -mrun .
-# use nsenter --net={A,B,C,D} to enter into network namespace of A/B/C/D.
+# use xnsenter {A,B,C,D} to enter into namespaces of A/B/C/D.
 #
 # Based on https://github.com/troglobit/smcroute/tree/master/test
 
-rm -f A B C D
-touch A B C D
+. lib.sh
+
 PID=$$
 
 # A-br0-B
-unshare --net=B --mount=B -- ip link set lo up
-nsenter --net=B -- ip link add ba type veth peer BA
-nsenter --net=B -- ip link set BA netns $PID
-nsenter --net=B -- ip link set ba up
+xunshare B -- ip link set lo up
+xnsenter B -- ip link add ba type veth peer BA
+xnsenter B -- ip link set BA netns $PID
+xnsenter B -- ip link set ba up
 ip link set BA up
 
-unshare --net=A -- ip link set lo up
-nsenter --net=A -- ip link add ab type veth peer AB
-nsenter --net=A -- ip link set AB netns $PID
-nsenter --net=A -- ip link set ab up
+xunshare A -- ip link set lo up
+xnsenter A -- ip link add ab type veth peer AB
+xnsenter A -- ip link set AB netns $PID
+xnsenter A -- ip link set ab up
 ip link set AB up
 
 ip link add br0 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -46,15 +46,15 @@ ip link set AB master br0
 ip link set br0 up
 
 # A-br1-C
-nsenter --net=A -- ip link add ac type veth peer AC
-nsenter --net=A -- ip link set AC netns $PID
-nsenter --net=A -- ip link set ac up
+xnsenter A -- ip link add ac type veth peer AC
+xnsenter A -- ip link set AC netns $PID
+xnsenter A -- ip link set ac up
 ip link set AC up
 
-unshare --net=C -- ip link set lo up
-nsenter --net=C -- ip link add ca type veth peer CA
-nsenter --net=C -- ip link set CA netns $PID
-nsenter --net=C -- ip link set ca up
+xunshare C -- ip link set lo up
+xnsenter C -- ip link add ca type veth peer CA
+xnsenter C -- ip link set CA netns $PID
+xnsenter C -- ip link set ca up
 ip link set CA up
 
 ip link add br1 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -63,15 +63,15 @@ ip link set AC master br1
 ip link set br1 up
 
 # C-br2-D
-nsenter --net=C -- ip link add cd type veth peer CD
-nsenter --net=C -- ip link set CD netns $PID
-nsenter --net=C -- ip link set cd up
+xnsenter C -- ip link add cd type veth peer CD
+xnsenter C -- ip link set CD netns $PID
+xnsenter C -- ip link set cd up
 ip link set CD up
 
-unshare --net=D -- ip link set lo up
-nsenter --net=D -- ip link add dc type veth peer DC
-nsenter --net=D -- ip link set DC netns $PID
-nsenter --net=D -- ip link set dc up
+xunshare D -- ip link set lo up
+xnsenter D -- ip link add dc type veth peer DC
+xnsenter D -- ip link set DC netns $PID
+xnsenter D -- ip link set dc up
 ip link set DC up
 
 ip link add br2 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -80,14 +80,14 @@ ip link set DC master br2
 ip link set br2 up
 
 # B-br3-D
-nsenter --net=B -- ip link add bd type veth peer BD
-nsenter --net=B -- ip link set BD netns $PID
-nsenter --net=B -- ip link set bd up
+xnsenter B -- ip link add bd type veth peer BD
+xnsenter B -- ip link set BD netns $PID
+xnsenter B -- ip link set bd up
 ip link set BD up
 
-nsenter --net=D -- ip link add db type veth peer DB
-nsenter --net=D -- ip link set DB netns $PID
-nsenter --net=D -- ip link set db up
+xnsenter D -- ip link add db type veth peer DB
+xnsenter D -- ip link set DB netns $PID
+xnsenter D -- ip link set db up
 ip link set DB up
 
 ip link add br3 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -96,21 +96,21 @@ ip link set DB master br3
 ip link set br3 up
 
 # addresses
-nsenter --net=B -- ip addr add 10.0.0.1/24 dev ba
-nsenter --net=A -- ip addr add 10.0.0.2/24 dev ab
-nsenter --net=C -- ip addr add 20.0.0.1/24 dev ca
-nsenter --net=A -- ip addr add 20.0.0.2/24 dev ac
-nsenter --net=B -- ip addr add 30.0.0.1/24 dev bd
-nsenter --net=D -- ip addr add 30.0.0.2/24 dev db
-nsenter --net=C -- ip addr add 40.0.0.1/24 dev cd
-nsenter --net=D -- ip addr add 40.0.0.2/24 dev dc
+xnsenter B -- ip addr add 10.0.0.1/24 dev ba
+xnsenter A -- ip addr add 10.0.0.2/24 dev ab
+xnsenter C -- ip addr add 20.0.0.1/24 dev ca
+xnsenter A -- ip addr add 20.0.0.2/24 dev ac
+xnsenter B -- ip addr add 30.0.0.1/24 dev bd
+xnsenter D -- ip addr add 30.0.0.2/24 dev db
+xnsenter C -- ip addr add 40.0.0.1/24 dev cd
+xnsenter D -- ip addr add 40.0.0.2/24 dev dc
 
 # multicast routing
-#nsenter --net=B -- ip route add 224.0.0.0/4 dev b1
-#nsenter --net=C -- ip route add 224.0.0.0/4 dev c1
+#xnsenter B -- ip route add 224.0.0.0/4 dev b1
+#xnsenter C -- ip route add 224.0.0.0/4 dev c1
 #
-#nsenter --net=A -- ip route add    224.0.0.0/4 dev a1   # NOTE on A 224.0.0.0/4 is routed
-#nsenter --net=A -- ip route append 224.0.0.0/4 dev a2   # to _both_ a1 and a2
+#xnsenter A -- ip route add    224.0.0.0/4 dev a1   # NOTE on A 224.0.0.0/4 is routed
+#xnsenter A -- ip route append 224.0.0.0/4 dev a2   # to _both_ a1 and a2
 
 
 
@@ -121,13 +121,13 @@ sed -e 's/IF0/ca/g' -e 's/IF1/cd/g' pim-dm.yaml.tmpl > pim-dm_C.yaml
 sed -e 's/IF0/dc/g' -e 's/IF1/db/g' pim-dm.yaml.tmpl > pim-dm_D.yaml
 
 # we need to mount private /var/run in each namespace so that pim-dm can be started
-#nsenter --net=A -- pim-dm -config pim-dm_A.yaml &
-#nsenter --net=B -- pim-dm -config pim-dm_B.yaml &
-#nsenter --net=C -- pim-dm -config pim-dm_C.yaml &
-#nsenter --net=D -- pim-dm -config pim-dm_D.yaml &
+#xnsenter A -- pim-dm -config pim-dm_A.yaml &
+#xnsenter B -- pim-dm -config pim-dm_B.yaml &
+#xnsenter C -- pim-dm -config pim-dm_C.yaml &
+#xnsenter D -- pim-dm -config pim-dm_D.yaml &
 
 # open terminals in A B C D for play
-nsenter --net=A -- xfce4-terminal --title=A &
-nsenter --net=B -- xfce4-terminal --title=B &
-nsenter --net=C -- xfce4-terminal --title=C &
-nsenter --net=D -- xfce4-terminal --title=D &
+xnsenter A -- xfce4-terminal --title=A &
+xnsenter B -- xfce4-terminal --title=B &
+xnsenter C -- xfce4-terminal --title=C &
+xnsenter D -- xfce4-terminal --title=D &