new

LDP/guide/docbook/abs-guide/echo-params.sh

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+#!/bin/bash
+# echo-params.sh
+
+# Call this script with a few command line parameters.
+# For example:
+#     sh echo-params.sh first second third fourth fifth
+
+params=$#              # Number of command-line parameters.
+param=1                # Start at first command-line param.
+
+while [ "$param" -le "$params" ]
+do
+  echo -n "Command line parameter "
+  echo -n \$$param     #  Gives only the *name* of variable.
+#         ^^^          #  $1, $2, $3, etc.
+                       #  Why?
+                       #  \$ escapes the first "$"
+                       #+ so it echoes literally,
+                       #+ and $param dereferences "$param" . . .
+                       #+ . . . as expected.
+  echo -n " = "
+  eval echo \$$param   #  Gives the *value* of variable.
+# ^^^^      ^^^        #  The "eval" forces the *evaluation*
+                       #+ of \$$
+                       #+ as an indirect variable reference.
+
+(( param ++ ))         # On to the next.
+done
+
+exit $?
+
+# =================================================
+
+$ sh echo-params.sh first second third fourth fifth
+Command line parameter $1 = first
+Command line parameter $2 = second
+Command line parameter $3 = third
+Command line parameter $4 = fourth
+Command line parameter $5 = fifth

LDP/guide/docbook/abs-guide/ip.sh

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+#!/bin/bash
+# Script by Juan Nicolas Ruiz
+# Used with his kind permission.
+
+# Setting up (and stopping) a GRE tunnel.
+
+
+# --- start-tunnel.sh ---
+
+LOCAL_IP="192.168.1.17"
+REMOTE_IP="10.0.5.33"
+OTHER_IFACE="192.168.0.100"
+REMOTE_NET="192.168.3.0/24"
+
+/sbin/ip tunnel add netb mode gre remote $REMOTE_IP \
+  local $LOCAL_IP ttl 255
+/sbin/ip addr add $OTHER_IFACE dev netb
+/sbin/ip link set netb up
+/sbin/ip route add $REMOTE_NET dev netb
+
+exit 0  #############################################
+
+# --- stop-tunnel.sh ---
+
+REMOTE_NET="192.168.3.0/24"
+
+/sbin/ip route del $REMOTE_NET dev netb
+/sbin/ip link set netb down
+/sbin/ip tunnel del netb
+
+exit 0