Shell Programming and Scripting

:) ~ $ tui-conf-get -l /etc/default/grub
GRUB_TIMEOUT
GRUB_DISTRIBUTOR
GRUB_DEFAULT
GRUB_DISABLE_SUBMENU
GRUB_TERMINAL_OUTPUT
GRUB_CMDLINE_LINUX
GRUB_DISABLE_RECOVERY
GRUB_THEME
GRUB_GFXMODE
GRUB_GFXPAYLOAD_LINUX

✔ ~ $ tui-conf-get /etc/default/grub GRUB_CMDLINE_LINUX
rd.luks.uuid luks-<guid-string> vconsole.font latarcyrheb-sun16 rd.luks.uuid luks-<guid-string> $([ -x /usr/sbin/rhcrashkernel-param ] && /usr/sbin/rhcrashkernel-param || :)✔ ~ $ 

+ ~ $ tui-conf-get /etc/default/grub GRUB_THEME
/boot/grub2/themes/circled-nasa-horizon/theme.txt:) ~ $ 

✔ ~ $ sudo tui-conf-set /etc/default/grub GRUB_THEME /boot/grub2/themes/circled-nasa-capsule/theme.txt
:) ~ $ tui-conf-get /etc/default/grub GRUB_THEME
/boot/grub2/themes/circled-nasa-capsule/theme.txt+ ~ $

...
	[[ -z "$2" ]] && printf "$help_text" && exit $RET_HELP
	while getopts "ilh" name
	do 	case $name in
		i)	OPT="-i"
			;;
		l)	grep -v ^# "$2"|grep "="|sed s,"="," ",g|awk '{print $1}'
			exit 0
			;;
		h)	printf "$help_text"
			exit $RET_HELP
			;;
		esac
	done
	shift $(($OPTIND - 1))
	CONFFILE="$1"
	VARNAME="$2"
	[[ ! -f "$CONFFILE" ]]  && echo "$CONFFILE dont exist?" "$TUI_FAIL" && exit 1
#
#	Display & Action
#
	VALUE=$(grep $OPT "${VARNAME}=" "$CONFFILE"|grep -v ^#|sed s,'"','',g|sed s,'=',' ',g) > /dev/zero
	VALUE="${VALUE:${#VARNAME}+1}"
	printf "$VALUE"

#
# 	Preformat strings
#
	SEARCH="$(grep $OPT "${VARNAME}=" "$CONFFILE"|grep -v ^#|tr -d [:space:])"
	$SMALL && VARNAME="${VARNAME,,}"
	$CAPS  && VARNAME="${VARNAME^^}"
	printf  "$SEARCH"|grep -q "\"" && \
		REPLACE="$VARNAME=\"$VALUE\"" || \
		REPLACE="$VARNAME=$VALUE"
	# Set proper SED 'divider'
	SD=","
	if echo "$REPLACE"|grep -q "$SD"
	then 	# Coma was found
		SD="/"
		printf "$REPLACE"|grep ","|grep "$SD"|grep -q '\\' && SD="\\"	# backslash was found
		[[ ! "$SD" = "/" ]] && \
			printf "$REPLACE"|grep ","|grep "$SD"|grep -q "/" && SD="|"	# Forward slash was found
	fi
	# Troubles with VARIABLES due to leading '$'
	printf "$SEARCH"|grep -q "\$" && \
		SEARCH="$(printf "$SEARCH"|sed s,'\$','\\\$',g)" && \
		hadDollar=true
	# FORUM EDIT: This was required to escape dollar signes, so they are not 'executed' or read
#
#	Display & Action
#
	# Generate the command
	cmd="$(which sed) s${SD}'${SEARCH}'${SD}'${REPLACE}'${SD}g -i \"$CONFFILE\""
	# Save changes
	if ! grep -q "$VARNAME" "$CONFFILE"
	then	# Its not there yet, just append it
		printf "${REPLACE}\n" >> "$CONFFILE"
	elif $hadDollar
	then	# FORUM EDIT: This is required to remove the escaped dollar signed, so the dollar sign is saved and not its (the variables) value.
	eval "$cmd"
	else	$cmd
	fi
	#
	# Return true if replaced string was found
	# This is required, since using RET=$? returned true eventhough value was not saved...
	grep -q "$REPLACE" "$CONFFILE"

sed 's|["$/\|\@]|\\&|g'