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www/eps/hpr2679/hpr2679_bash13_ex2.sh

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+#!/bin/bash
+
+# =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~
+# IP Address parsing revisited
+# =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~ =~
+#
+# An IP address looks like this:
+#       192.168.0.5
+# Four groups of 1-3 numbers in the range 0..255 separated by dots.
+#
+re='^([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})$'
+
+#
+# The address is expected as the only argument
+#
+if [[ $# -ne 1 ]]; then
+    echo "Usage: $0 IP_address"
+    exit 1
+fi
+
+#
+# Validate against the regex
+#
+if [[ $1 =~ $re ]]; then
+    #
+    # Look at the components and check they are all in range
+    #
+    errs=0
+    problems=
+    for i in {1..4}; do
+        d="${BASH_REMATCH[$i]}"
+        if [[ $d -lt 0 || $d -gt 255 ]]; then
+            ((errs++))
+            problems+="$d "
+        fi
+    done
+
+    #
+    # Report any problems found
+    #
+    if [[ $errs -gt 0 ]]; then
+        problems="${problems:0:-1}"
+        echo "$1 is not a valid IP address; contains ${problems// /, }"
+        exit 1
+    fi
+
+    echo "$1 is a valid IP address"
+else
+    echo "$1 is not a valid IP address"
+fi