====== Dialog Boxes ======
\\
There are multiple dialog boxes tools. Choice mainly depend on features you need.
Very light, go with Whiptail. More advanced (file explorer, date/time, file editor, forms, etc), but still simple, go with Dialog. Advanced (like GUI with multiple windows, menu, etc), go with Newt.

===== Whiptail =====

Whiptail is used directly from bash.

Example is better than words sometime:

<code bash>
while true; do

  choice=$(whiptail --title "Choose dialog to open" --menu "Please choose a dialog to open" 0 0 0 \
  "1" "inputbox" \
  "2" "yesno" \
  "3" "msgbox" \
  "4" "passwordbox" \
  "5" "gauge" \
  "6" "textbox" \
  "7" "exit" 3>&1 1>&2 2>&3)

  case "$choice" in
    1)
       inputboxresult=$(whiptail --inputbox "This is an inputbox" --title "inputbox" 0 0 3>&1 1>&2 2>&3)
       echo $inputboxresult
       ;;
    2)
       whiptail  --yesno "This is a yesno box" --title "yesno" 0 0
       echo $?
       ;;
    3)
       whiptail  --msgbox "This is a msgbox" --title "msgbox" 0 0
       echo $?
       ;;
    4)
       passwordboxresult=$(whiptail --passwordbox "This is a passwordbox" --title "passwordbox" 0 0 3>&1 1>&2 2>&3)
       echo $passwordboxresult
       ;;
    5)
       (
cat <<EOF
XXX
10
This is step one...
XXX
EOF
touch myfile > /dev/null
sleep 1s
cat <<EOF
XXX
70
This is step two...
XXX
EOF
touch myfile > /dev/null
sleep 1s
cat <<EOF
XXX
100
This is step three...
XXX
EOF
sleep 1
) | whiptail --gauge "Please wait..." 6 50 0
       ;;
    6)
       echo "hello" > /tmp/myfile
       echo "world" >> /tmp/myfile
       echo "!" >> /tmp/myfile
       whiptail --textbox --scrolltext /tmp/myfile 20 0
       echo $?
       ;;
    7)
       break
       ;;
  esac

done
</code>

Good documentation:

https://en.wikibooks.org/wiki/Bash_Shell_Scripting/Whiptail

===== Dialog =====

Dialog is used directly from bash. On most distributions, you need to install dialog (yum install dialog).
Dialog syntax is very close to Whiptail.

Example is better than words sometime:

<code bash>

while true; do

  choice=$(dialog --backtitle "My dialog example" --title "Choose dialog to open" --menu "Please choose a dialog to open" 0 50 0 \
  "1" "inputbox" \
  "2" "yesno" \
  "3" "msgbox" \
  "4" "passwordbox" \
  "5" "gauge" \
  "6" "textbox" \
  "7" "exit" 3>&1 1>&2 2>&3)

  case "$choice" in
    1)
       inputboxresult=$(dialog --backtitle "My dialog example" --title "inputbox" --inputbox "This is an inputbox" 8 50 3>&1 1>&2 2>&3)
       echo $inputboxresult
       ;;
    2)
       dialog --ascii-lines --backtitle "My dialog example" --title "yesno" --yesno "This is a yesno box" 6 50
       echo $?
       ;;
    3)
       dialog --colors --backtitle "My dialog example" --title "msgbox" --msgbox "This \Zb\Z1is a msg\Znbox" 6 50
       echo $?
       ;;
    4)
       passwordboxresult=$(dialog --backtitle "My dialog example" --title "passwordbox" --passwordbox "This is a passwordbox" 8 50 3>&1 1>&2 2>&3)
       echo $passwordboxresult
       ;;
    5)
       (
cat <<EOF
XXX
10
This is step one...
XXX
EOF
touch myfile > /dev/null
sleep 1s
cat <<EOF
XXX
70
This is step two...
XXX
EOF
touch myfile > /dev/null
sleep 1s
cat <<EOF
XXX
100
This is step three...
XXX
EOF
sleep 1
) | dialog --backtitle "My dialog example" --gauge "Please wait..." 7 50 0
       ;;
    6)
       echo "hello" > /tmp/myfile
       echo "world" >> /tmp/myfile
       echo "!" >> /tmp/myfile
       dialog --backtitle "My dialog example" --textbox /tmp/myfile 20 0
       echo $?
       ;;
    7)
       break
       ;;
  esac

done
</code>

Note: if you get strange characters instead of lines and you are using putty on windows, use --ascci-lines for each dialog command, or before opening ssh, go into putty configuration, then in Connection -> Data, change Terminalt-type string from xterm to linux. Ensure also that in Window -> Translation, UTF-8 is used.

Good documentation:

http://www.unixcl.com/2009/12/linux-dialog-utility-short-tutorial.html

===== Newt =====

Newt is based on C language, but is very powerfull.

First install some packages (here on centos):

<code>yum install newt newt-devel slang-devel</code>

Then an ugly example would be:

<code C>
#include <newt.h>
#include <stdlib.h>
#include <stdio.h>

int main(void) {

void * result;
    struct partition * curr;
    newtInit();
    newtCls();

    newtDrawRootText(0, 0, "My manager");
    newtDrawRootText(4, 4, "This is a test manager");
    newtDrawRootText(4, 6, "All actions done here are logged in /var/log/manager.log");

    newtComponent win1, form, b1, b2, listbox;
    win1 = newtOpenWindow(10, 10, 80, 30, "Button Sample");
    b1 = newtButton(10, 9, "Ok");
    b2 = newtButton(22, 9, "Cancel");
    listbox= newtListbox(10,15,2, NEWT_FLAG_RETURNEXIT);
    newtListboxAppendEntry(listbox, "do nothing" , "1");
    newtListboxAppendEntry(listbox, "touch file" , "2");
    form = newtForm(NULL, NULL, 0);
    newtFormAddComponents(form, b1, b2, listbox, NULL);
    newtRunForm(form);
    result = newtListboxGetCurrent(listbox);


    newtFormDestroy(form);
    newtPopWindow();

    newtFinished();
    const char * toto=result;
    printf("%c\n",*toto);
    printf("%p\n",result);
    if ( toto == "2" )
    {int status = system("touch /tmp/testr");}
}
</code>

To build it:

<code>gcc -o test.out test.c -lnewt</code>

Full documentation can be found at: http://gnewt.sourceforge.net/tutorial.html\\
To get more informations on functions: https://sourcecodebrowser.com/newt/0.52.10/listbox_8c.html