From 11818aeee42717a9ce5ca1b4ac7bde4a646f1306 Mon Sep 17 00:00:00 2001
From: Ian Kelling <ian@iankelling.org>
Date: Thu, 19 Jan 2017 02:30:46 -0800
Subject: [PATCH] even better documentation

---
 newns | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/newns b/newns
index 31f1b52..d6a1b08 100755
--- a/newns
+++ b/newns
@@ -37,7 +37,7 @@ fi
 
 usage() {
     cat <<EOF
-usage: ${0##*/} [OPTS] start|stop NETNS_NAME
+usage: ${0##*/} [OPTS] start|stop NS_NAME
 Setup new or systemd created network namespace with nat and mount namespace
 
 -c, --create    Create network namespace. For running outside systemd private net.
@@ -54,7 +54,7 @@ Also create a named mount namespace under /root/mount_namespaces, so we
 can alter some system config for this namespace. Subsequent systemd
 command lines would be prefixed with:
 
-/usr/bin/nsenter --mount=/root/mount_namespaces/NETNS_NAME
+/usr/bin/nsenter --mount=/root/mount_namespaces/NS_NAME
 
 Note, this means that they can't run as unpriveledged users, but once
 systemd 233 comes out, it will have a bind mount option from within unit
@@ -69,7 +69,7 @@ in a directory adjacent to the absolute, resolved directory this file is
 in.
 
 Background: "ip netns new ..." also does a mount namespace, then bind
-mounts each file/dir in /etc/netns/NETNS_NAME to /etc/NETNS_NAME. Note,
+mounts each file/dir in /etc/netns/NS_NAME to /etc/NS_NAME. Note,
 for openvpn having it's own resolv.conf by using it's user script which
 calls resolvconf, this doesn't help much. What we actually want to do is
 copy /run/resolvconf somehwere then bind mount it on top of
@@ -82,7 +82,7 @@ EOF
 }
 
 
-## begin arg parsing ##
+#### begin arg parsing ####
 create=false
 temp=$(getopt -l help,create hc "$@") || usage 1
 eval set -- "$temp"
@@ -99,11 +99,10 @@ if (( $# != 2 )); then
 fi
 
 action=$1
-nn=$2 # network namespace / namespace name
-## end arg parsing ##
-
-## begin sanity checking ##
+nn=$2 # namespace name
+#### end arg parsing ####
 
+#### begin sanity checking ####
 install_error=false
 if ! type -p ip &>/dev/null; then
     echo "please install the iproute2 package"
@@ -116,8 +115,7 @@ fi
 if $install_error; then
     exit 1
 fi
-
-##   end sanity checking ##
+####   end sanity checking ####
 
 
 v0=veth0-$nn
@@ -128,10 +126,10 @@ if ! $create && [[ $(readlink /proc/self/ns/net) == "$(readlink /proc/1/ns/net)"
     create=true
 fi
 
+# make the default network namespace be named
 target=/run/netns/default
 if [[ ! -e $target && ! -L $target ]]; then
     mkdir -p /run/netns
-    # make the default network namespace be named
     ln -s /proc/1/ns/net $target
 fi
 
@@ -146,7 +144,7 @@ fi
 dexec() { ip netns exec default "$@"; }
 
 
-# head -n1 is defensive. Not sure if there is some weird feature
+# background: head -n1 is defensive. Not sure if there is some weird feature
 # for 2 routes to be 0/0.
 gateway_if=$(ipd route list exact 0/0 | head -n1| sed -r 's/.*\s(\S+)\s*$/\1/')
 nat() { dexec iptables -t nat $1 POSTROUTING -o $gateway_if -j MASQUERADE \
@@ -168,13 +166,13 @@ find_network() {
 }
 
 start() {
-
     find_network
     if ! $found; then
         echo "$0: error: no open network found"
         exit 1
     fi
 
+    #### begin mount namespace setup ####
     mkdir -p /root/mount_namespaces
     if ! mountpoint /root/mount_namespaces >/dev/null; then
         mount --bind /root/mount_namespaces /root/mount_namespaces
@@ -186,6 +184,7 @@ start() {
     if ! mountpoint /root/mount_namespaces/$nn >/dev/null; then
         unshare --mount=/root/mount_namespaces/$nn
     fi
+    ####   end mount namespace setup ####
 
 
     if $create; then
@@ -193,8 +192,6 @@ start() {
         ip -n $nn link set dev lo up
     fi
 
-
-
     echo 1 | dexec dd of=/proc/sys/net/ipv4/ip_forward 2>/dev/null
 
     _errcatch_cleanup=stop
-- 
2.30.2