Fix issues found with shellcheck

thebookofcolors

@@ -10,19 +10,19 @@ random_rgb_color_pair() {
 	red="$(random_channel_strength)"
 	green="$(random_channel_strength)"
 	blue="$(random_channel_strength)"
-	printf "$red;$green;$blue|$((255 - $red));$((255 - green));$((255 - blue))"
+	printf "%s;%s;%s|$((255 - red));$((255 - green));$((255 - blue))" "$red" "$green" "$blue"
 }
 
 thebookofcolors() {
 	colors=$(random_rgb_color_pair)
-	foreground="$(echo $colors | cut -d '|' -f 1)"
-	background="$(echo $colors | cut -d '|' -f 2)"
-	printf "\e[38;2;${foreground}m"
-	printf "\e[48;2;${background}m"
+	foreground="$(echo "$colors" | cut -d '|' -f 1)"
+	background="$(echo "$colors" | cut -d '|' -f 2)"
+	printf "\e[38;2;%sm" "$foreground"
+	printf "\e[48;2;%sm" "$background"
 	if test -z "$1"; then
 		printf "The Book of Colors"
 	else
-		printf "$1"
+		printf "%s" "$1"
 	fi
 	printf "\e[0m"
 }
@@ -33,7 +33,7 @@ newline() {
 		return
 	fi
 
-	for i in $(seq 1 $1); do
+	for i in $(seq 1 "$1"); do
 		printf "\n"
 	done
 }
@@ -45,7 +45,7 @@ title() {
 	fi
 
 	printf "\e[1;4;37m"
-	printf "$1"
+	printf "%s" "$1"
 	printf "\e[0m\n"
 }
 
@@ -56,7 +56,7 @@ subtitle() {
 	fi
 
 	printf "\e[4;37m"
-	printf "$1"
+	printf "%s" "$1"
 	printf "\e[0m"
 	if test -z "$2"; then printf "\n"; fi
 }
@@ -72,7 +72,7 @@ italic() {
 	fi
 
 	printf "\e[3;37m"
-	printf "$1"
+	printf "%s" "$1"
 	printf "\e[0m"
 }
 
@@ -229,7 +229,7 @@ section_8bit_colors() {
 
 	subtitle "A Table of Available Colors"
 	for i in $(seq 0 255); do
-		if test "$(echo $i % 8 | bc)" = "0" -a "$i" != "0"; then
+		if test "$(echo "$i" % 8 | bc)" = "0" -a "$i" != "0"; then
 			printf "\n"
 		fi
 
@@ -464,7 +464,7 @@ section_strikethrough() {
 section_using_escape_sequences_in_shell_prompt() {
 	title "Using Escape Sequences in Shell Prompts"
 
-	printf "When using these sequences in a Bash prompt (e.g. $PS1), it's possible for issues to arise because of Bash \"miscounting\" the number of characters in the prompt string.\n"
+	printf "When using these sequences in a Bash prompt (e.g. \$PS1), it's possible for issues to arise because of Bash \"miscounting\" the number of characters in the prompt string.\n"
 	printf "This is often the source of difficult-to-debug (or describe) issues with the terminal, such as characters being moved around or overwritten seemingly at random.\n"
 	newline
 
@@ -481,7 +481,7 @@ section_table_of_all_sgr_commands() {
 	newline
 
 	for i in $(seq 0 107); do
-		if test "$(echo $i % 10 | bc)" = "0" -a "$i" != "0"; then
+		if test "$(echo "$i" % 10 | bc)" = "0" -a "$i" != "0"; then
 			printf "\n"
 		fi
 
@@ -582,7 +582,7 @@ main() {
 	newline
 }
 
-name="$(basename $0)"
+name="$(basename "$0")"
 if test "$name" = "thebookofcolors"; then
 	main | less -R
 fi