diff --git a/contrib/devtools/gen-manpages.sh b/contrib/devtools/gen-manpages.sh
index fb9496b54..607c40181 100755
--- a/contrib/devtools/gen-manpages.sh
+++ b/contrib/devtools/gen-manpages.sh
@@ -14,8 +14,8 @@ ZCASHTX=${ZCASHTX:-$SRCDIR/zcash-tx}
 
 # The autodetected version git tag can screw up manpage output a little bit
 read -r -a ZECVERSTR <<< "$($ZCASHCLI --version | head -n1 | awk '{ print $NF }')"
-read -r -a ZECVER <<< "$(echo $ZECVERSTR | awk -F- '{ OFS="-"; NF--; print $0; }')"
-read -r -a ZECCOMMIT <<< "$(echo $ZECVERSTR | awk -F- '{ print $NF }')"
+read -r -a ZECVER <<< "$(echo ${ZECVERSTR[0]} | awk -F- '{ OFS="-"; NF--; print $0; }')"
+read -r -a ZECCOMMIT <<< "$(echo ${ZECVERSTR[0]} | awk -F- '{ print $NF }')"
 
 # Create a footer file with copyright content.
 # This gets autodetected fine for zcashd if --version-string is not set,
@@ -26,14 +26,14 @@ grep -v "Bitcoin Core Developers" footer.h2m >footer-no-bitcoin-copyright.h2m
 
 for cmd in $ZCASHD $ZCASHCLI $ZCASHTX; do
   cmdname="${cmd##*/}"
-  help2man -N --version-string=$ZECVER --include=footer.h2m -o ${MANDIR}/${cmdname}.1 ${cmd}
-  sed -i "s/\\\-$ZECCOMMIT//g" ${MANDIR}/${cmdname}.1
+  help2man -N --version-string=${ZECVER[0]} --include=footer.h2m -o ${MANDIR}/${cmdname}.1 ${cmd}
+  sed -i "s/\\\-${ZECCOMMIT[0]}//g" ${MANDIR}/${cmdname}.1
 done
 
 for cmd in $ZCASHD_WALLET_TOOL; do
   cmdname="${cmd##*/}"
-  help2man -N --version-string=$ZECVER --include=footer-no-bitcoin-copyright.h2m -o ${MANDIR}/${cmdname}.1 ${cmd}
-  sed -i "s/\\\-$ZECCOMMIT//g" ${MANDIR}/${cmdname}.1
+  help2man -N --version-string=${ZECVER[0]} --include=footer-no-bitcoin-copyright.h2m -o ${MANDIR}/${cmdname}.1 ${cmd}
+  sed -i "s/\\\-${ZECCOMMIT[0]}//g" ${MANDIR}/${cmdname}.1
 done
 
 rm -f footer.h2m
diff --git a/contrib/devtools/update-clang-hashes.sh b/contrib/devtools/update-clang-hashes.sh
index 586df3b24..0e64360bb 100755
--- a/contrib/devtools/update-clang-hashes.sh
+++ b/contrib/devtools/update-clang-hashes.sh
@@ -7,9 +7,8 @@ SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
 CLANG_PACKAGE="$SCRIPT_DIR/../../depends/packages/native_clang.mk"
 LIBCXX_PACKAGE="$SCRIPT_DIR/../../depends/packages/libcxx.mk"
 
-CLANG_MAJOR_VERSION=$( cat $CLANG_PACKAGE | grep -oP "_major_version=\K.*" )
-CLANG_VERSION=$( cat $CLANG_PACKAGE | grep -v _major_version | grep -oP "_version=\K.*" )
-LIBCXX_MSYS2_VERSION=$( cat $LIBCXX_PACKAGE | grep -oP "_msys2_version=\K.*" )
+CLANG_VERSION=$( grep -v _major_version $CLANG_PACKAGE | grep -oP "_version=\K.*" )
+LIBCXX_MSYS2_VERSION=$( grep -oP "_msys2_version=\K.*" $LIBCXX_PACKAGE )
 
 update_clang_hash() {
     url="https://github.com/llvm/llvm-project/releases/download/llvmorg-$CLANG_VERSION/clang+llvm-$CLANG_VERSION-$1.tar.xz"
diff --git a/contrib/devtools/update-rust-hashes.sh b/contrib/devtools/update-rust-hashes.sh
index ad036bebf..2073439ff 100755
--- a/contrib/devtools/update-rust-hashes.sh
+++ b/contrib/devtools/update-rust-hashes.sh
@@ -5,7 +5,7 @@ export LC_ALL=C
 SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
 RUST_PACKAGE="$SCRIPT_DIR/../../depends/packages/native_rust.mk"
 
-RUST_VERSION=$( cat $RUST_PACKAGE | grep -oP "_version=\K.*" )
+RUST_VERSION=$( grep -oP "_version=\K.*" $RUST_PACKAGE )
 
 update_hash() {
     url="https://static.rust-lang.org/dist/$1-$RUST_VERSION-$2.tar.gz"
diff --git a/test/lint/lint-cargo-patches.sh b/test/lint/lint-cargo-patches.sh
index 742dbb392..eef5798ba 100755
--- a/test/lint/lint-cargo-patches.sh
+++ b/test/lint/lint-cargo-patches.sh
@@ -13,7 +13,7 @@ CARGO_TOML="$REPOBASE/Cargo.toml"
 CONFIG_FILE="$REPOBASE/.cargo/config.offline"
 
 CARGO_TOML_PATCH_PREFIX="[patch.crates-io]"
-let CARGO_TOML_PATCH_START=$(grep -Fn "$CARGO_TOML_PATCH_PREFIX" $CARGO_TOML | cut -d: -f1)+1
+(( CARGO_TOML_PATCH_START=$(grep -Fn "$CARGO_TOML_PATCH_PREFIX" $CARGO_TOML | cut -d: -f1)+1 ))
 if [ "$CARGO_TOML_PATCH_START" -eq 1 ]; then
     # We have no patched dependencies to lint.
     exit
diff --git a/zcutil/afl/afl-build.sh b/zcutil/afl/afl-build.sh
index 9cf1e7e34..7562518c5 100755
--- a/zcutil/afl/afl-build.sh
+++ b/zcutil/afl/afl-build.sh
@@ -6,7 +6,8 @@ set -eu -o pipefail
 AFL_HARDEN=1
 CONFIGURE_FLAGS="--enable-tests=no --enable-fuzz-main"
 ZCUTIL=$(realpath "./zcutil")
-export AFL_LOG_DIR="$(pwd)"
+AFL_LOG_DIR="$(pwd)"
+export AFL_LOG_DIR
 
 for d in src/fuzzing/*/ ; do
     fuzz_cases+="$(basename "$d"), "
@@ -79,7 +80,7 @@ while (( "$#" )); do
             ZCUTIL=$(realpath "$2")
             shift 2
         ;;
-        -*|--*=)
+        -?|--*=)
             echo "Error: Unsupported flag $1" >&2
             help
             exit 1
diff --git a/zcutil/afl/afl-get.sh b/zcutil/afl/afl-get.sh
index 4e349414c..93740b66a 100755
--- a/zcutil/afl/afl-get.sh
+++ b/zcutil/afl/afl-get.sh
@@ -39,7 +39,7 @@ while (( "$#" )); do
             help
             exit 0
         ;;
-        -*|--*=)
+        -?|--*=)
             echo "Error: Unsupported flag $1" >&2
             help
             exit 1
diff --git a/zcutil/afl/afl-getbuildrun.sh b/zcutil/afl/afl-getbuildrun.sh
index 028ee6419..1c762751f 100755
--- a/zcutil/afl/afl-getbuildrun.sh
+++ b/zcutil/afl/afl-getbuildrun.sh
@@ -11,7 +11,8 @@ FUZZ_OPTIONS_STRING="Options are: ${fuzz_cases::-2}"
 
 required_options_count=0
 
-export AFL_INSTALL_DIR=$(realpath "./afl-temp")
+AFL_INSTALL_DIR=$(realpath "./afl-temp")
+export AFL_INSTALL_DIR
 
 function help {
     cat <<EOF
@@ -47,7 +48,7 @@ while (( "$#" )); do
             help
             exit 0
         ;;
-        -*|--*=)
+        -?|--*=)
             echo "Error: Unsupported flag $1" >&2
             help
             exit 1
diff --git a/zcutil/afl/afl-run.sh b/zcutil/afl/afl-run.sh
index e6872d9c2..600e383bf 100755
--- a/zcutil/afl/afl-run.sh
+++ b/zcutil/afl/afl-run.sh
@@ -46,7 +46,7 @@ while (( "$#" )); do
             help
             exit 0
         ;;
-        -*|--*=)
+        -?|--*=)
             echo "Error: Unsupported flag $1" >&2
             help
             exit 1
diff --git a/zcutil/build.sh b/zcutil/build.sh
index 8423a375c..3a7c32192 100755
--- a/zcutil/build.sh
+++ b/zcutil/build.sh
@@ -23,7 +23,7 @@ cd "$(dirname "$("$READLINK" -f "$0")")/.."
 # Allow user overrides to $MAKE. Typical usage for users who need it:
 #   MAKE=gmake ./zcutil/build.sh -j$(nproc)
 if [ -z "${MAKE-}" ]; then
-    MAKE=make
+    MAKE="make"
 fi
 
 # Allow overrides to $BUILD and $HOST for porters. Most users will not need it.
diff --git a/zcutil/cleanup-tags.sh b/zcutil/cleanup-tags.sh
index cc1c970e7..806e81b24 100755
--- a/zcutil/cleanup-tags.sh
+++ b/zcutil/cleanup-tags.sh
@@ -20,7 +20,7 @@ for nonzctag in $(git ls-remote origin \
                  )
 do
     git push origin ":refs/tags/${nonzctag}" &
-    i="$(expr "$i" + 1)"
+    i=$((i + 1))
     [ "$i" -ge "$MAXJOBS" ] && wait -n
 done
 
diff --git a/zcutil/fetch-params.sh b/zcutil/fetch-params.sh
index 69d2e964d..b60fecb63 100755
--- a/zcutil/fetch-params.sh
+++ b/zcutil/fetch-params.sh
@@ -35,7 +35,7 @@ ZC_DISABLE_CURL="${ZC_DISABLE_CURL:-}"
 LOCKFILE=/tmp/fetch_params.lock
 
 fetch_wget() {
-    if [ -z "$WGETCMD" ] || ! [ -z "$ZC_DISABLE_WGET" ]; then
+    if [ -z "$WGETCMD" ] || [ -n "$ZC_DISABLE_WGET" ]; then
         return 1
     fi
 
@@ -53,7 +53,7 @@ EOF
 }
 
 fetch_ipfs() {
-    if [ -z "$IPFSCMD" ] || ! [ -z "$ZC_DISABLE_IPFS" ]; then
+    if [ -z "$IPFSCMD" ] || [ -n "$ZC_DISABLE_IPFS" ]; then
         return 1
     fi
 
@@ -66,7 +66,7 @@ EOF
 }
 
 fetch_curl() {
-    if [ -z "$CURLCMD" ] || ! [ -z "$ZC_DISABLE_CURL" ]; then
+    if [ -z "$CURLCMD" ] || [ -n "$ZC_DISABLE_CURL" ]; then
         return 1
     fi
 
diff --git a/zcutil/libfuzzer/libfuzzer-build.sh b/zcutil/libfuzzer/libfuzzer-build.sh
index 9ad59b88a..b6379f5ec 100755
--- a/zcutil/libfuzzer/libfuzzer-build.sh
+++ b/zcutil/libfuzzer/libfuzzer-build.sh
@@ -22,12 +22,12 @@ usage() {
     echo "Where fuzzer is an entry in ./src/fuzzing/*, the default sanitizer"
     echo "is \"address\" and default instrument is ( \"^.*/src/$\" )."
     echo ""
-    exit -1
+    exit 255
 }
 
 die() {
     echo $1
-    exit -1
+    exit 255
 }
 
 # parse command line options
@@ -120,11 +120,12 @@ fi
 
 set -x
 
-export ZCUTIL=$(realpath "./zcutil")
+ZCUTIL=$(realpath "./zcutil")
+export ZCUTIL
 
 # overwrite the Linux make profile to use clang instead of GCC:
 
-cat $ZCUTIL/../depends/hosts/linux.mk | sed -e 's/=gcc/=clang/g' | sed -e 's/=g++/=clang++/g' > x
+sed -e 's/=gcc/=clang/g' $ZCUTIL/../depends/hosts/linux.mk | sed -e 's/=g++/=clang++/g' > x
 mv x $ZCUTIL/../depends/hosts/linux.mk
 
 # the build_stage distinction helps to layer an intermediate docker
@@ -134,7 +135,7 @@ mv x $ZCUTIL/../depends/hosts/linux.mk
 if [ "$BUILD_STAGE" = "depends" ]
 then
     # make an empty fuzz file just so we can build dependencies
-    > src/fuzz.cpp
+    true > src/fuzz.cpp
 else
     cp "./src/fuzzing/$FUZZER_NAME/fuzz.cpp" src/fuzz.cpp || die "Can't copy fuzz.cpp for that fuzzer"
 fi