some sytem scripts

shell_scripts/lessons/TRICKS.md

@@ -50,4 +50,48 @@ Useful Cmds:
 List size of folders
 $ du -sh *
 
+Print calendar:
+$ cal
 
+Writing and creating a file:
+$ cat > NEWFILE
+
+--- write here ---
+^D
+
+
+De-bug Shell Script
+-------------------
+
+Use -v and -x option:
+$ sh option SCRIPT
+$ bash option SCRIPT
+
+
+Local and Global Variables
+-------------------------
+
+Whenever you type:
+$ /bin/bash
+You start a new shell where the previous variables will be forgotten (local variables). To make variables global, you can do:
+$ export VARIABLE-NAME
+Before changing shell.
+
+
+Conditional Execution
+---------------------
+
+The control operators are && (AND) and || (OR).
+$ rm myf && echo "File is removed successfully" || echo "File is not removed"
+
+
+Functions
+---------
+
+$ SayHello()
+{
+   echo "Hello $LOGNAME, Have nice computing"
+   return
+}
+To execute this SayHello() function just type it name as follows:
+$ SayHello

shell_scripts/lessons/average_number.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+
+avg=0
+temp_total=0
+number_of_args=$#
+
+#
+# First see the sufficient cmd args
+#
+if [ $# -lt 2 ] ; then
+   echo -e "Opps! I need atleast 2 command line args\n"
+   echo -e "Syntax: $0: number1 number2 ... numberN\n"
+   echo -e "Example:$0 5 4\n\t$0 56 66 34"
+   exit 1
+fi
+
+#
+# now calculate the average of numbers given on command line as cmd args
+#
+
+for i in $*
+do
+
+   #  addition of all the numbers on cmd args
+   temp_total=`expr $temp_total + $i`
+
+done
+
+avg=`expr $temp_total / $number_of_args`
+echo "Average of all number is $avg"

shell_scripts/lessons/case_loop_example.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+# script to test case statement
+
+if [ -z $1 ]
+  then
+  r="*** unknown ***"
+elif [ -n $1 ]
+  then
+  r=$1
+fi
+
+case $r in
+  "car") echo "car rental";;
+  "van") echo "van rental";;
+  "jeep") echo "jeep rental";;
+  *) echo "Sorry I have no $r !";;
+esac

shell_scripts/lessons/cheesboard.sh

@@ -5,7 +5,7 @@ for (( i = 1; i <= 9; i++ ))
 do
   for (( j = 1; j <= 9; j++))
   do
-    tot=`expr $i + $j`
+    tot=`expr $i + $j` # notice that these tot must have no space to =
     tmp=`expr $tot % 2`
     if [ $tmp -eq 0 ]; then
       echo -e -n "\033[47m  "

shell_scripts/lessons/factorial.sh

@@ -0,0 +1,18 @@
+#! /bin/bash
+
+n=0
+on=0
+fact=1
+
+echo -n "Enter number to find factorial : "
+read n
+
+on=$n
+
+while [ $n -ge  1 ]
+do
+  fact=`expr $fact \* $n`
+  n=`expr $n - 1`
+done
+
+echo "Factorial for $on is $fact"

shell_scripts/lessons/file_descriptors.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# from > & destination
+
+if [ $# -ne 2 ]
+  then
+  echo "Error!" 1>&2
+  echo "Usae: $0 number1 number2"
+  exit 1
+fi
+ans=`expr $1 + $2`
+echo "Sum = $ans"

shell_scripts/lessons/getopts.sh

@@ -0,0 +1,59 @@
+#!/bin/sh
+
+
+
+# Usage: ./geotopts.sh -n -a -s -w -d
+#
+#
+# help_ani() To print help
+#
+help_ani()
+{
+  echo "Usage: $0 -n -a -s -w -d"
+  echo "Options: These are optional argument"
+  echo " -n name of animal"
+  echo " -a age of animal"
+  echo " -s sex of animal "
+  echo " -w weight of animal"
+  echo " -d demo values (if any of the above options are used "
+  echo " their values are not taken)"
+  exit 1
+}
+#
+#Start main procedure
+#
+#
+#Set default value for variable
+#
+isdef=0
+na=Moti
+age="2 Months" # may be 60 days, as U like it!
+sex=Male
+weight=3Kg
+#
+#if no argument
+#
+if [ $# -lt 1 ]; then
+  help_ani
+fi
+while getopts n:a:s:w:d opt
+do
+  case "$opt" in
+    n) na="$OPTARG";;
+    a) age="$OPTARG";;
+    s) sex="$OPTARG";;
+    w) weight="$OPTARG";;
+    d) isdef=1;;
+    \?) help_ani;;
+  esac
+done
+if [ $isdef -eq 0 ]
+then
+  echo "Animal Name: $na, Age: $age, Sex: $sex, Weight: $weight (user define mode)"
+else
+  na="Pluto Dog"
+  age=3
+  sex=Male
+  weight=20kg
+  echo "Animal Name: $na, Age: $age, Sex: $sex, Weight: $weight (demo mode)"
+fi

shell_scripts/lessons/hex_converter_real_numbers.sh

@@ -0,0 +1,10 @@
+#! /bin/bash
+
+n=0
+hex=0
+echo "Decimal to hexadecimal converter:"
+echo -n "Enter number in decimal format : "
+read n
+hex=`echo "obase=16;ibase=10; $n" | bc`
+echo "$n is equivalent \"$hex\" in hexadecimal"
+

shell_scripts/lessons/menu_fancy.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+#
+#         dialog --title {title} --backtitle {backtitle} {Box options}
+#        where Box options can be any one of following
+#       --yesno      {text}  {height} {width}
+#       --msgbox     {text}  {height} {width}
+#       --infobox    {text}  {height} {width}
+#       --inputbox   {text}  {height} {width} [{init}]
+#       --textbox    {file}  {height} {width}
+#      --menu       {text}  {height} {width} {menu} {height} {tag1} item1}...
+#
+#
+
+dialog \
+--title "Hello $LOGNAME" \
+--backtitle "Linux Shell Script - Bytegirl Tutorial" \
+--msgbox "This is dialog box called infobox, which is used \
+to show some information on screen, Thanks to Savio Lam and\
+Stuart Herbert to give us this utility. Press any key. . . " \
+9 50 ; read
+
+
+
+dialog --title "Alert : Delete File" --backtitle "Linux Shell Script\
+Tutorial" --yesno "\nDo you want to delete '/usr/letters/jobapplication'\
+file" 7 60
+sel=$?
+case $sel in
+   0) echo "User select to delete file";;
+   1) echo "User select not to delete file";;
+   255) echo "Canceled by user by pressing [ESC] key";;
+esac
+
+
+
+$ cat > dia4
+dialog --title "Inputbox - To take input from you" --backtitle "Linux Shell\
+Script Tutorial" --inputbox "Enter your name please" 8 60 2>/tmp/input.$$
+
+sel=$?
+
+na=`cat /tmp/input.$$`
+case $sel in
+  0) echo "Hello $na" ;;
+  1) echo "Cancel is Press" ;;
+  255) echo "[ESCAPE] key pressed" ;;
+esac
+
+rm -f /tmp/input.$$

shell_scripts/lessons/real_numbers.sh

@@ -0,0 +1,26 @@
+#! /bin/bash
+
+
+a=0
+b=0
+number_of_args=$#
+
+#
+# First see the sufficient cmd args
+#
+if [ $# -lt 2 ] ; then
+   echo -e "Opps! I need atleast 2 command line args\n"
+   echo -e "Syntax: $0: number1 number2 ... numberN\n"
+   echo -e "Example:$0 5 4\n\t$0 56 66 34"
+   exit 1
+fi
+
+#
+# now calculate the average of numbers given on command line as cmd args
+#
+
+a=$1
+b=$2
+
+c=`echo $a + $b | bc`
+echo "$a + $b = $c"

shell_scripts/lessons/red_hello_world.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+
+clear
+echo -e "\033[1m Hello World"
+ # bold effect
+echo -e "\033[5m Blink"
+       # blink effect
+echo -e "\033[0m Hello World"
+ # back to noraml
+
+echo -e "\033[31m Hello World"
+ # Red color
+echo -e "\033[32m Hello World"
+ # Green color
+echo -e "\033[33m Hello World"
+ # See remaing on screen
+echo -e "\033[34m Hello World"
+echo -e "\033[35m Hello World"
+echo -e "\033[36m Hello World"
+
+echo -e -n "\033[0m "
+  # back to noraml
+
+echo -e "\033[41m Hello World"
+echo -e "\033[42m Hello World"
+echo -e "\033[43m Hello World"
+echo -e "\033[44m Hello World"
+echo -e "\033[45m Hello World"
+echo -e "\033[46m Hello World"
+
+
+echo -e "\033[0m Hello World"

shell_scripts/lessons/while_loop_example.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# script to test while statement
+
+if [ $# -eq 0 ] # note the spaces
+then
+  echo "Error, missing argument!"
+exit 1
+fi
+n=$1
+i=1
+while [ $i -le 10 ]
+do
+  echo "$n * $i = `expr $i \* $n`"
+  i=`expr $i + 1`
+done