dialog --title "Linux Dialog Utility Infobox" --backtitle "Linux Shell Script\
Tutorial" --infobox "This is dialog box called infobox, which is used \
to show some information on screen. Press any key. . . " 7 50
-------------------------- output
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
-------------------------- input
 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.$$
--------------------------
#How to create small menu using dialog
#
dialog --backtitle "Linux Shell Script Tutorial " --title "Main\
Menu" --menu "Move using [UP] [DOWN],[Enter] to\
Select" 15 50 3\
Date/time "Shows Date and Time"\
Calendar "To see calendar "\
Editor "To start vi editor " 2>/tmp/menuitem.$$

menuitem=`cat /tmp/menuitem.$$`

opt=$?

case $menuitem in
Date/time) date;;
Calendar) cal;;
Editor) vi;;
esac
--------------------------	remove files (including names with spaces)
find /home -type f -name "*.txt" -print0 | xargs -0 rm -f

------------------	testing for command-line parameters

case "$1" in
"") echo "Usage: ${0##*/} <filename>"; exit 65;;  # No command-line parameters,
                                                  # or first parameter empty.
# Note that ${0##*/} is ${var##pattern} param substitution. Net result is $0.

-*) FILENAME=./$1;;   # If filename passed as argument ($1) starts with a dash,
                      # replace it with ./$1
                      # so further commands don't interpret it as an option.

* ) FILENAME=$1;;     # Otherwise, $1.
esac
------------------	
# Using command substitution to generate a "case" variable.

case $( arch ) in   # "arch" returns machine architecture.
i386 ) echo "80386-based machine";;
i486 ) echo "80486-based machine";;
i586 ) echo "Pentium-based machine";;
i686 ) echo "Pentium2+-based machine";;
*    ) echo "Other type of machine";;
esac

exit 0
------------------
match_string ()
{
  MATCH=0
  NOMATCH=90
  PARAMS=2     # Function requires 2 arguments.
  BAD_PARAMS=91

  [ $# -eq $PARAMS ] || return $BAD_PARAMS

  case "$1" in
  "$2") return $MATCH;;
  *   ) return $NOMATCH;;
  esac

}
a=one
b=two
c=three
d=two

match_string $a     # wrong number of parameters
echo $?             # 91
match_string $a $b  # no match
echo $?             # 90
match_string $b $d  # match
echo $?             # 0

exit 0
------------------
# isalpha.sh: Using a "case" structure to filter a string.

SUCCESS=0
FAILURE=-1

isalpha ()  # Tests whether *first character* of input string is alphabetic.
{
if [ -z "$1" ]                # No argument passed?
then
  return $FAILURE
fi

case "$1" in
[a-zA-Z]*) return $SUCCESS;;  # Begins with a letter?
*        ) return $FAILURE;;
esac
}             # Compare this with "isalpha ()" function in C.

isalpha2 ()   # Tests whether *entire string* is alphabetic.
{
  [ $# -eq 1 ] || return $FAILURE

  case $1 in
  *[!a-zA-Z]*|"") return $FAILURE;;
               *) return $SUCCESS;;
  esac
}

isdigit ()    # Tests whether *entire string* is numerical.
{             # In other words, tests for integer variable.
  [ $# -eq 1 ] || return $FAILURE

  case $1 in
  *[!0-9]*|"") return $FAILURE;;
            *) return $SUCCESS;;
  esac
}

check_var ()  # Front-end to isalpha ().
{
if isalpha "$@"
then
  echo "\"$*\" begins with an alpha character."
  if isalpha2 "$@"
  then        # No point in testing if first char is non-alpha.
    echo "\"$*\" contains only alpha characters."
  else
    echo "\"$*\" contains at least one non-alpha character."
  fi  
else
  echo "\"$*\" begins with a non-alpha character."
              # Also "non-alpha" if no argument passed.
fi

echo

}

digit_check ()  # Front-end to isdigit ().
{
if isdigit "$@"
then
  echo "\"$*\" contains only digits [0 - 9]."
else
  echo "\"$*\" has at least one non-digit character."
fi

echo

}

a=23skidoo
b=H3llo
c=-What?
d=What?
e=`echo $b`   # Command substitution.
f=AbcDef
g=27234
h=27a34
i=27.34

check_var $a
check_var $b
check_var $c
check_var $d
check_var $e
check_var $f
check_var     # No argument passed, so what happens?
#
digit_check $g
digit_check $h
digit_check $i


exit 0
------------------

------------------
------------------