style: Improve readability by adding quotes and consistent spacing in builder script

Author: dogi

builder

@@ -4,13 +4,13 @@ source lib.sh
 # Raspbian
 RASPBIAN_TORRENT_URL=downloads.raspberrypi.org/raspios_arm64/images/raspios_arm64-2024-11-19/2024-11-19-raspios-bookworm-arm64.img.xz.torrent
 RASPBIAN_SHA256=ea6e68c48d14c3d78af5471c0b288bbf6522fdd775241f74d8295d106d344300
-RASPBIAN_IMAGE_FILE=$(basename $RASPBIAN_TORRENT_URL | sed -e "s/.xz.torrent//g")
+RASPBIAN_IMAGE_FILE=$(basename "$RASPBIAN_TORRENT_URL" | sed -e 's/.xz.torrent//g')
 EXTRA_IMAGE_SIZE=1978MB
 MINIMAL_SPACE_LEFT=111111
 
 missing_deps=()
 for prog in kpartx wget gpg parted qemu-arm-static aria2c jq curl; do
-    if ! type $prog &>/dev/null ; then
+    if ! type "$prog" &>/dev/null; then
         missing_deps+=( "$prog" )
     fi
 done
@@ -47,9 +47,9 @@ function _decompress_image {
 function _disable_daemons {
     # Prevent services from being started inside the chroot.
     POLICY_RC_D=mnt/img_root/usr/sbin/policy-rc.d
-    echo "#!/bin/sh" >> $POLICY_RC_D
-    echo "exit 101"  >> $POLICY_RC_D
-    chmod +x $POLICY_RC_D
+    echo "#!/bin/sh" >> "$POLICY_RC_D"
+    echo "exit 101"  >> "$POLICY_RC_D"
+    chmod +x "$POLICY_RC_D"
 }
 
 function _enable_daemons {
@@ -60,16 +60,16 @@ function _enable_daemons {
 function _disable_ld_preload {
     cfg=mnt/img_root/etc/ld.so.preload
 
-    if grep -q '^[^#]' $cfg; then
-        sed -i -e 's/^/#/' $cfg || die "Could not disable ld.so.preload"
+    if grep -q '^[^#]' "$cfg"; then
+        sed -i -e 's/^/#/' "$cfg" || die "Could not disable ld.so.preload"
     fi
 }
 
 function _enable_ld_preload {
     cfg=mnt/img_root/etc/ld.so.preload
 
-    if grep -q '^#' $cfg; then
-        sed -i -e 's/^#//' $cfg || die "Could not enable ld.so.preload"
+    if grep -q '^#' "$cfg"; then
+        sed -i -e 's/^#//' "$cfg" || die "Could not enable ld.so.preload"
     fi
 }