How do I create a terminal-based GUI?

The screenshot in the question looks like whiptail (a functionally-reduced program imitating dialog, using newt rather than ncurses). The way the title and buttons are rendered is built into each program, making them look different.

Here is a script which duplicates the original screenshot, for either whiptail or dialog:

#!/bin/sh : ${DIALOG:=dialog} case "$DIALOG" in *dialog*) OPTS="$OPTS --cr-wrap" high=10 ;; *whiptail*) high=12 ;; esac rows=$(stty size | cut -d' ' -f1) [ -z "$rows" ] && rows=$high [ $rows -gt $high ] && rows=$high cols=$(stty size | cut -d' ' -f2) $DIALOG --backtitle "Package configuration" \ --title "Configuring sun-java6-jre" \ $OPTS \ --yesno '\nIn order to install this package, you must accept the license terms, the "Operating System Distributor License for Java" (DLJ), v1.1. Not accepting will cancel the installation.\n\nDo you accept the DLJ license terms?' $rows $((cols - 5)) 

and for comparison, screenshot with whiptail:

and with dialog:

Besides the different appearance of the title and buttons, dialog uses different colors by default (though that is configurable—see screenshots), and it uses fewer lines on the screen.

dialog (and whiptail) use libraries for managing the display of lines, colors, etc. But you may also see newt used in Red Hat anaconda program as a shared library called from python (with the same appearance). Along the same lines, the kernel configuration program started as a (cut-down) copy of dialog, and then evolved into features using a shared library (without the original lxdialog program) much like the way newt is used from python.

From bash — you could use either dialog or whiptail for the most commonly-used features. Someone wrote a wrapper for those (in perl) to allow scripts to more readily use either those or a few others, but you're better off using dialog directly since the perl module is essentially common-denominator.

The dialog sources include examples of all of the widgets along with most of the command-line options:

cdialog (ComeOn Dialog!) version 1.3-20160424 Copyright 2000-2015,2016 Thomas E. Dickey This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * Display dialog boxes from shell scripts * Usage: cdialog <options> { --and-widget <options> } where options are "common" options, followed by "box" options Special options: [--create-rc "file"] Common options: [--ascii-lines] [--aspect <ratio>] [--backtitle <backtitle>] [--beep] [--beep-after] [--begin <y> <x>] [--cancel-label <str>] [--clear] [--colors] [--column-separator <str>] [--cr-wrap] [--date-format <str>] [--default-button <str>] [--default-item <str>] [--defaultno] [--exit-label <str>] [--extra-button] [--extra-label <str>] [--help-button] [--help-label <str>] [--help-status] [--help-tags] [--hfile <str>] [--hline <str>] [--ignore] [--input-fd <fd>] [--insecure] [--item-help] [--keep-tite] [--keep-window] [--last-key] [--max-input <n>] [--no-cancel] [--no-collapse] [--no-cr-wrap] [--no-items] [--no-kill] [--no-label <str>] [--no-lines] [--no-mouse] [--no-nl-expand] [--no-ok] [--no-shadow] [--no-tags] [--nook] [--ok-label <str>] [--output-fd <fd>] [--output-separator <str>] [--print-maxsize] [--print-size] [--print-version] [--quoted] [--scrollbar] [--separate-output] [--separate-widget <str>] [--shadow] [--single-quoted] [--size-err] [--sleep <secs>] [--stderr] [--stdout] [--tab-correct] [--tab-len <n>] [--time-format <str>] [--timeout <secs>] [--title <title>] [--trace <file>] [--trim] [--version] [--visit-items] [--week-start <str>] [--yes-label <str>] Box options: --buildlist <text> <height> <width> <list-height> <tag1> <item1> <status1>... --calendar <text> <height> <width> <day> <month> <year> --checklist <text> <height> <width> <list height> <tag1> <item1> <status1>... --dselect <directory> <height> <width> --editbox <file> <height> <width> --form <text> <height> <width> <form height> <label1> <l_y1> <l_x1> <item1> <i_y1> <i_x1> <flen1> <ilen1>... --fselect <filepath> <height> <width> --gauge <text> <height> <width> [<percent>] --infobox <text> <height> <width> --inputbox <text> <height> <width> [<init>] --inputmenu <text> <height> <width> <menu height> <tag1> <item1>... --menu <text> <height> <width> <menu height> <tag1> <item1>... --mixedform <text> <height> <width> <form height> <label1> <l_y1> <l_x1> <item1> <i_y1> <i_x1> <flen1> <ilen1> <itype>... --mixedgauge <text> <height> <width> <percent> <tag1> <item1>... --msgbox <text> <height> <width> --passwordbox <text> <height> <width> [<init>] --passwordform <text> <height> <width> <form height> <label1> <l_y1> <l_x1> <item1> <i_y1> <i_x1> <flen1> <ilen1>... --pause <text> <height> <width> <seconds> --prgbox <text> <command> <height> <width> --programbox <text> <height> <width> --progressbox <text> <height> <width> --radiolist <text> <height> <width> <list height> <tag1> <item1> <status1>... --rangebox <text> <height> <width> <min-value> <max-value> <default-value> --tailbox <file> <height> <width> --tailboxbg <file> <height> <width> --textbox <file> <height> <width> --timebox <text> <height> <width> <hour> <minute> <second> --treeview <text> <height> <width> <list-height> <tag1> <item1> <status1> <depth1>... --yesno <text> <height> <width> Auto-size with height and width = 0. Maximize with height and width = -1. Global-auto-size if also menu_height/list_height = 0. 

Further reading:

• dialog
• ncurses
• Anaconda/Features/NoLoader
• How to create GUIs (such as menuconfig) with lxdialog

I believe the package you are looking for is ncurses.

Wikipedia describes ncurses as follows:

ncurses (new curses) is a programming library providing an API that allows the programmer to write text-based user interfaces in a terminal-independent manner. It is a toolkit for developing "GUI-like" application software that runs under a terminal emulator

It is widely used, for example, in the menuconfig kernel configuration tool:

Since you are using bash, you can use Bash Simple Curses (as mentioned by Runium in the comment below).

zenity

zenity --file-selection --directory 

.

# var means variable var\ =$( zenity --entry \ --title="title" \ --text="text" \ --entry-text="entry text" \ ) \ && echo "$var" 

password=$(zenity --password) 

file="$(zenity --file-selection)" 

# ls is a command to list files in a directory ls $(zenity --file-selection --directory) 

# Help

zenity --help 

zenity --help-general 

zenity --help-entry 

other graphical user interfaces (gui)

dialog 

dialog \ --backtitle "backtitle" \ --title "title" \ --yesno \ "bla bla bla...\n\n Do you accept?" \ 0 -1 echo $? 

stops further execution of the script , breaks it . the command echo $? , will never happen