myhomework

alive2.sh

+#!/bin/bash
+# alive2.sh
+
+expand_ip_range() {
+  IFS='-' read -r start end <<< "$1"
+  IFS='.' read -r i1 i2 i3 i4 <<< "$start"
+  IFS='.' read -r _ _ _ e4 <<< "$end"
+  for ip in $(seq $i4 $e4); do
+    echo $i1.$i2.$i3.$ip
+  done
+}
+
+for ip in $(expand_ip_range $1); do
+  ping -c2 $ip &> /dev/null
+  if [ $? = 0 ]; then
+    echo "$ip is UP"
+  else
+    echo "$ip is DOWN"
+  fi
+done

ex2.txt

+mkdir ~/newfolder
+
+for i in {1..10}; do
+  for j in {a..z}; do
+    touch ~/newfolder/file${i}_${j}
+  done
+done
+
+echo "hello Linux" | tee ~/newfolder/*_x
+
+
+for letter in {a..z}; do
+  mkdir ~/newfolder/$letter
+  mv ~/newfolder/*_$letter ~/newfolder/$letter/
+done
+
+
+rm ~/newfolder/*3* ~/newfolder/*4*

shell.sh

+#!/bin/bash
+
+oldword=$1
+newword=$2
+extension=$3
+
+find . -type f - name "*.$extension" -exec sed -i ""s/$oldword/$newword/g" {} +