contrib: shell scripts: add quotes around more variables

diff --git a/contrib/build-wine/sign.sh b/contrib/build-wine/sign.sh
index 51cc244..ecdd305 100755
--- a/contrib/build-wine/sign.sh
+++ b/contrib/build-wine/sign.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-here=$(dirname "$0")
+here="$(dirname "$0")"
 if [ -z "$WIN_SIGNING_PASSWORD" ]; then
     echo "password missing"
     exit 1
diff --git a/contrib/build-wine/unsign.sh b/contrib/build-wine/unsign.sh
index 380c6ba..3ec2516 100755
--- a/contrib/build-wine/unsign.sh
+++ b/contrib/build-wine/unsign.sh
@@ -5,9 +5,9 @@ set -e
 
 PROJECT_ROOT="$(dirname "$(readlink -e "$0")")/../.."
 CONTRIB="$PROJECT_ROOT/contrib"
-here=$(dirname "$0")
+here="$(dirname "$0")"
 test -n "$here" -a -d "$here" || exit
-cd $here
+cd "$here"
 
 if ! which osslsigncode > /dev/null 2>&1; then
     echo "Please install osslsigncode"
diff --git a/contrib/build_tools_util.sh b/contrib/build_tools_util.sh
index 10adbf7..2dd9b8b 100755
--- a/contrib/build_tools_util.sh
+++ b/contrib/build_tools_util.sh
@@ -35,7 +35,7 @@ function verify_signature() {
 
 function verify_hash() {
     local file=$1 expected_hash=$2
-    actual_hash=$(sha256sum $file | awk '{print $1}')
+    actual_hash=$(sha256sum "$file" | awk '{print $1}')
     if [ "$actual_hash" == "$expected_hash" ]; then
         return 0
     else
@@ -47,8 +47,8 @@ function verify_hash() {
 
 function download_if_not_exist() {
     local file_name=$1 url=$2
-    if [ ! -e $file_name ] ; then
-        wget -O $file_name "$url"
+    if [ ! -e "$file_name" ] ; then
+        wget -O "$file_name" "$url"
     fi
 }
 
diff --git a/contrib/freeze_containers_distro.sh b/contrib/freeze_containers_distro.sh
index f942079..132f817 100755
--- a/contrib/freeze_containers_distro.sh
+++ b/contrib/freeze_containers_distro.sh
@@ -9,7 +9,7 @@ DEBIAN_APPIMAGE_DISTRO="bullseye"  # should match build-linux/appimage Dockerfil
 DEBIAN_WINE_DISTRO="bookworm"    # should match build-wine Dockerfile base
 DEBIAN_ANDROID_DISTRO="bookworm" # should match android Dockerfile base
 
-contrib=$(dirname "$0")
+contrib="$(dirname "$0")"
 
 
 if [ ! -x /bin/wget ]; then
@@ -17,7 +17,7 @@ if [ ! -x /bin/wget ]; then
     exit 1
 fi
 
-DEBIAN_SNAPSHOT_LATEST=$(wget -O- ${DEBIAN_SNAPSHOT_BASE}$(date +"?year=%Y&month=%m") 2>/dev/null | grep "^<a href=\"20" | tail -1 | sed -e 's#[^"]*"\(.\{17,17\}\).*#\1#')
+DEBIAN_SNAPSHOT_LATEST=$(wget -O- "${DEBIAN_SNAPSHOT_BASE}$(date +"?year=%Y&month=%m")" 2>/dev/null | grep "^<a href=\"20" | tail -1 | sed -e 's#[^"]*"\(.\{17,17\}\).*#\1#')
 
 if [ "${DEBIAN_SNAPSHOT_LATEST}x" = "x" ]; then
     echo "could not find timestamp for debian packages"
@@ -32,15 +32,15 @@ wget -O /dev/null ${DEBIAN_SNAPSHOT} 2>/dev/null
 echo "Valid!"
 
 # build-linux
-echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main" >$contrib/build-linux/appimage/apt.sources.list
-echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main" >>$contrib/build-linux/appimage/apt.sources.list
+echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main" > "$contrib/build-linux/appimage/apt.sources.list"
+echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main" >> "$contrib/build-linux/appimage/apt.sources.list"
 
 # build-wine
-echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main" >$contrib/build-wine/apt.sources.list
-echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main" >>$contrib/build-wine/apt.sources.list
+echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main" > "$contrib/build-wine/apt.sources.list"
+echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main" >> "$contrib/build-wine/apt.sources.list"
 
 # android
-echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main" >$contrib/android/apt.sources.list
-echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main" >>$contrib/android/apt.sources.list
+echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main" > "$contrib/android/apt.sources.list"
+echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main" >> "$contrib/android/apt.sources.list"
 
 echo "updated APT sources to ${DEBIAN_SNAPSHOT}"
diff --git a/contrib/freeze_packages.sh b/contrib/freeze_packages.sh
index e295720..1a5dcc6 100755
--- a/contrib/freeze_packages.sh
+++ b/contrib/freeze_packages.sh
@@ -4,13 +4,13 @@
 set -e
 
 venv_dir=~/.electrum-venv
-contrib=$(dirname "$0")
+contrib="$(dirname "$0")"
 
 # note: we should not use a higher version of python than what the binaries bundle
 if [[ ! "$SYSTEM_PYTHON" ]] ; then
     SYSTEM_PYTHON=$(which python3.10) || printf ""
 else
-    SYSTEM_PYTHON=$(which $SYSTEM_PYTHON) || printf ""
+    SYSTEM_PYTHON=$(which "$SYSTEM_PYTHON") || printf ""
 fi
 if [[ ! "$SYSTEM_PYTHON" ]] ; then
     echo "Please specify which python to use in \$SYSTEM_PYTHON" && exit 1
@@ -18,15 +18,15 @@ fi
 
 which virtualenv > /dev/null 2>&1 || { echo "Please install virtualenv" && exit 1; }
 
-${SYSTEM_PYTHON} -m hashin -h > /dev/null 2>&1 || { ${SYSTEM_PYTHON} -m pip install hashin; }
+"${SYSTEM_PYTHON}" -m hashin -h > /dev/null 2>&1 || { "${SYSTEM_PYTHON}" -m pip install hashin; }
 
 for suffix in '' '-hw' '-binaries' '-binaries-mac' '-build-wine' '-build-mac' '-build-base' '-build-appimage' '-build-android'; do
     reqfile="requirements${suffix}.txt"
 
     rm -rf "$venv_dir"
-    virtualenv -p ${SYSTEM_PYTHON} $venv_dir
+    virtualenv -p "${SYSTEM_PYTHON}" "$venv_dir"
 
-    source $venv_dir/bin/activate
+    source "$venv_dir/bin/activate"
 
     echo "Installing dependencies... (${reqfile})"
 
@@ -42,7 +42,7 @@ for suffix in '' '-hw' '-binaries' '-binaries-mac' '-build-wine' '-build-mac' '-
 
     requirements=$(pip freeze --all)
 
-    restricted=$(echo $requirements | ${SYSTEM_PYTHON} $contrib/deterministic-build/find_restricted_dependencies.py)
+    restricted=$(echo $requirements | ${SYSTEM_PYTHON} "$contrib/deterministic-build/find_restricted_dependencies.py")
     if [ ! -z "$restricted" ]; then
         python -m pip install $restricted
         requirements=$(pip freeze --all)
diff --git a/contrib/make_libsecp256k1.sh b/contrib/make_libsecp256k1.sh
index 3d8d916..8b194c9 100755
--- a/contrib/make_libsecp256k1.sh
+++ b/contrib/make_libsecp256k1.sh
@@ -21,7 +21,7 @@ LIBSECP_VERSION="a660a4976efe880bae7982ee410b9e0dc59ac983"
 
 set -e
 
-. $(dirname "$0")/build_tools_util.sh || (echo "Could not source build_tools_util.sh" && exit 1)
+. "$(dirname "$0")/build_tools_util.sh" || (echo "Could not source build_tools_util.sh" && exit 1)
 
 here="$(dirname "$(realpath "$0" 2> /dev/null || grealpath "$0")")"
 CONTRIB="$here"
diff --git a/contrib/make_libusb.sh b/contrib/make_libusb.sh
index f796622..4666cae 100755
--- a/contrib/make_libusb.sh
+++ b/contrib/make_libusb.sh
@@ -5,7 +5,7 @@ LIBUSB_VERSION="d52e355daa09f17ce64819122cb067b8a2ee0d4b"
 
 set -e
 
-. $(dirname "$0")/build_tools_util.sh || (echo "Could not source build_tools_util.sh" && exit 1)
+. "$(dirname "$0")/build_tools_util.sh" || (echo "Could not source build_tools_util.sh" && exit 1)
 
 here="$(dirname "$(realpath "$0" 2> /dev/null || grealpath "$0")")"
 CONTRIB="$here"
diff --git a/contrib/make_zbar.sh b/contrib/make_zbar.sh
index e4cd184..e286f30 100755
--- a/contrib/make_zbar.sh
+++ b/contrib/make_zbar.sh
@@ -15,7 +15,7 @@ ZBAR_VERSION="bb05ec54eec57f8397cb13fb9161372a281a1219"
 
 set -e
 
-. $(dirname "$0")/build_tools_util.sh || (echo "Could not source build_tools_util.sh" && exit 1)
+. "$(dirname "$0")/build_tools_util.sh" || (echo "Could not source build_tools_util.sh" && exit 1)
 
 here="$(dirname "$(realpath "$0" 2> /dev/null || grealpath "$0")")"
 CONTRIB="$here"
diff --git a/contrib/osx/make_osx.sh b/contrib/osx/make_osx.sh
index 80dd707..5f20324 100755
--- a/contrib/osx/make_osx.sh
+++ b/contrib/osx/make_osx.sh
@@ -55,8 +55,8 @@ break_legacy_easy_install
 # This helps to avoid older versions of pip-installed dependencies interfering with the build.
 VENV_DIR="$CONTRIB_OSX/build-venv"
 rm -rf "$VENV_DIR"
-python3 -m venv $VENV_DIR
-source $VENV_DIR/bin/activate
+python3 -m venv "$VENV_DIR"
+source "$VENV_DIR/bin/activate"
 
 # don't add debug info to compiled C files (e.g. when pip calls setuptools/wheel calls gcc)
 # see https://github.com/pypa/pip/issues/6505#issuecomment-526613584
diff --git a/contrib/release.sh b/contrib/release.sh
index 931fbf1..1119f78 100755
--- a/contrib/release.sh
+++ b/contrib/release.sh
@@ -311,7 +311,7 @@ else
     test -f "$PROJECT_ROOT/dist/$apk3"       || fail "apk3 not found among built files"
     test -f "$PROJECT_ROOT/dist/$dmg"        || fail "dmg not found among built files"
 
-    if [ $REV != $VERSION ]; then
+    if [ "$REV" != "$VERSION" ]; then
         fail "versions differ, not uploading"
     fi
 
diff --git a/electrum-env b/electrum-env
index a10a698..0cd7436 100755
--- a/electrum-env
+++ b/electrum-env
@@ -13,7 +13,7 @@
 
 set -e
 
-cd $(dirname $0)
+cd "$(dirname "$0")"
 if [ -e ./env/bin/activate ]; then  # existing venv
     source ./env/bin/activate
 else  # create new venv