Use -r with every `read` (according to ShellCheck)

99bottles.sh

     #
     local oneBottle=false   # 'true' if this line affects the following line
     local line              # every line
-    while read line; do
+    while read -r line; do
         line="${line/one more bottles/one more bottle}"
         case "$line" in
             *"one of those bottles"*)   line="$(
     # Fix capitalization of each line on stdin
     #
     local line      # every line
-    while read line; do
+    while read -r line; do
         echo -n "${line:0:1}" | tr '[:lower:]' '[:upper:]'
         echo "${line#?}"
     done
     # Add punctuation to each line on stdin
     #
     local line      # every line
-    while read line; do
+    while read -r line; do
         case "${line}" in
             [Ii]f*)     echo "${line},";;
             '')         echo;;
     local first     # first word of a line
     local rest      # remainder of a line
     local syl       # number of syllables in the first word
-    while read first rest; do
+    while read -r first rest; do
         case "$rest" in
             *beer*)
                 first=${first/zero/no}