Bash - How to make each menu selections in 1 line instead of multiple selections in 1 line

Question

Im making a tool script for my theme has 6 options: 1) Check theme update 2) Reinstall theme 3) Install font 4) Install wallpaper 5) Check tool update 6) Quit

Here is the code

clear
echo "==========================="
echo "Tool for theme"
echo "==========================="

function check_update {
echo "checking theme update"
}

function reinstall_theme {
echo "Reinstalling"
echo "==========================="
}

function font {
echo "Installing font"
}

function wall {
echo "Installing wallpaper"
}

function check_update_tool {
echo "Checking tool update"
}

all_done=0
while (( !all_done )); do
options=("Check theme update" "Reinstall theme" "Install font" "Install wallpaper" "Check tool update" "Quit")

echo "Choose an option: "
select opt in "${options[@]}"; do
case $REPLY in
1) check_update; break ;;
2) reinstall_theme; break ;;
3) font; break ;;
4) wall; break ;;
5) check_update_tool; break ;;
6) all_done=1; break ;;
*) echo "Invalid option" ;;
esac
done
done

echo "Exiting"
sleep 2

But when I run it, the selections of menu mess up

==================
Tool for theme
==================
Choose an option:
1) Check theme update 2) Reinstall theme  3) Install font
4) Install Wallpaper     5) Check tool update      6) Quit

But what I want is

===============
Tool for theme
===============
Choose an option:
1) Check theme update
2) Reinstall theme
3) Install font
4) Install wallpaper
5) Check tool update
6) Quit

So how can I fix the menu?

Answer 1

You can set the COLUMNS variable to limit the width of the display, e.g., if you set it to 12, it will format your example into a single column:

COLUMNS=12
select opt in "${options[@]}"; do
case $REPLY in
1) check_update; break ;;
2) reinstall_theme; break ;;
3) font; break ;;
4) wall; break ;;
5) check_update_tool; break ;;
6) all_done=1; break ;;
*) echo "Invalid option" ;;
esac

produces

===========================
Tool for theme
===========================
Choose an option: 
1) Check theme update
2) Reinstall theme
3) Install font
4) Install wallpaper
5) Check tool update
6) Quit
#? 

The bash manual describes COLUMNS:

Used by the select command to determine the terminal width when printing selection lists. Automatically set if the checkwinsize option is enabled (see The Shopt Builtin), or in an interactive shell upon receipt of a SIGWINCH.

Besides seeing the feature in the manual page, it helps to read the source code to get the complete story. This variable is used in the select_query function, with the comment

/* Print the elements of LIST, one per line, preceded by an index from 1 to
   LIST_LEN.  Then display PROMPT and wait for the user to enter a number.
   If the number is between 1 and LIST_LEN, return that selection.  If EOF
   is read, return a null string.  If a blank line is entered, or an invalid
   number is entered, the loop is executed again. */

and later, in the select_query function

  t = get_string_value ("COLUMNS");
  COLS =  (t && *t) ? atoi (t) : 80;

If you give a reasonable value, atoi gives reasonable results (even zero in this case would be plausible, since that is less than 80 columns, and would be returned by atoi if you set COLUMNS to a nonnumeric value). If there's no value, (i.e. COLUMNS=""), bash uses 80 columns.

Further reading:

• atoi - convert a string to an integer

  The call atoi(str) shall be equivalent to:
  (int) strtol(str, (char **)NULL, 10)

• strtol, strtoll - convert a string to a long integer

  If no conversion could be performed, 0 shall be returned