diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 994a5f3..95b7359 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,6 @@ env:
   CARGO_TERM_COLOR: always
 permissions:
   contents: read
-
 jobs:
   ci:
     name: ${{ matrix.os }}
@@ -22,41 +21,34 @@ jobs:
       - uses: actions/checkout@v3
         with:
           fetch-depth: 0
-
       - uses: actions-rs/toolchain@v1
         if: ${{ matrix.os == 'windows-latest' }}
         with:
           components: clippy
           profile: minimal
           toolchain: stable
-
       - uses: actions-rs/toolchain@v1
         if: ${{ matrix.os == 'windows-latest' }}
         with:
           components: rustfmt
           profile: minimal
           toolchain: nightly
-
       - uses: cachix/install-nix-action@v20
         if: ${{ matrix.os != 'windows-latest' }}
         with:
           nix_path: nixpkgs=channel:nixos-unstable
-
       - uses: cachix/cachix-action@v12
         if: ${{ matrix.os != 'windows-latest' && env.CACHIX_AUTH_TOKEN != '' }}
         with:
           authToken: ${{ env.CACHIX_AUTH_TOKEN }}
           name: zoxide
-
       - name: Setup cache
         uses: Swatinem/rust-cache@v2
         with:
           key: ${{ matrix.os }}
-
       - name: Install just
         uses: taiki-e/install-action@v2
         with:
           tool: just
-
       - name: Run lints + tests
         run: just lint test
diff --git a/.github/workflows/no-response.yml b/.github/workflows/no-response.yml
index b73a46c..a23313f 100644
--- a/.github/workflows/no-response.yml
+++ b/.github/workflows/no-response.yml
@@ -17,6 +17,6 @@ jobs:
           daysUntilClose: 30
           responseRequiredLabel: waiting-for-response
           closeComment: >
-            This issue has been automatically closed due to inactivity. If you
-            feel this is still relevant, please comment here or create a fresh
-            issue.
+            This issue has been automatically closed due to inactivity. If you feel
+            this is still relevant, please comment here or create a fresh issue.
+
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 8e81859..efa9466 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -8,7 +8,6 @@ env:
   CARGO_INCREMENTAL: 0
 permissions:
   contents: write
-
 jobs:
   release:
     name: ${{ matrix.target }}
@@ -27,12 +26,10 @@ jobs:
           - os: ubuntu-latest
             target: aarch64-unknown-linux-musl
             deb: true
-
           - os: macos-11
             target: x86_64-apple-darwin
           - os: macos-11
             target: aarch64-apple-darwin
-
           - os: windows-latest
             target: x86_64-pc-windows-msvc
           - os: windows-latest
@@ -42,14 +39,12 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 0
-
       - name: Get version
         id: get_version
         uses: SebRollen/toml-action@v1.0.2
         with:
           file: Cargo.toml
           field: package.version
-
       - name: Install Rust
         uses: actions-rs/toolchain@v1
         with:
@@ -57,51 +52,41 @@ jobs:
           profile: minimal
           override: true
           target: ${{ matrix.target }}
-
       - name: Setup cache
         uses: Swatinem/rust-cache@v1.0.2
         with:
           key: ${{ matrix.target }}
-
       - name: Build binary
         uses: actions-rs/cargo@v1
         with:
           command: build
           args: --release --locked --target=${{ matrix.target }} --color=always --verbose
           use-cross: ${{ runner.os == 'Linux' }}
-
       - name: Install cargo-deb
         if: ${{ matrix.deb == true }}
         uses: actions-rs/install@v0.1
         with:
           crate: cargo-deb
-
       - name: Build deb
         if: ${{ matrix.deb == true }}
         uses: actions-rs/cargo@v1
         with:
           command: deb
           args: --no-build --no-strip --output=. --target=${{ matrix.target }}
-
       - name: Package (*nix)
         if: runner.os != 'Windows'
-        run: >
-          tar -cv
-          CHANGELOG.md LICENSE README.md
-          man/
-          -C contrib/ completions/ -C ../
-          -C target/${{ matrix.target }}/release/ zoxide
-          | gzip --best
-          > 'zoxide-${{ steps.get_version.outputs.value }}-${{ matrix.target }}.tar.gz'
+        run: |
+          tar -cv CHANGELOG.md LICENSE README.md man/ \
+            -C contrib/ completions/ -C ../ \
+            -C target/${{ matrix.target }}/release/ zoxide |
+            gzip --best > \
+            zoxide-${{ steps.get_version.outputs.value }}-${{ matrix.target }}.tar.gz
       - name: Package (Windows)
         if: runner.os == 'Windows'
-        run: >
-          7z a 'zoxide-${{ steps.get_version.outputs.value }}-${{ matrix.target }}.zip'
-          CHANGELOG.md LICENSE README.md
-          ./man/
-          ./contrib/completions/
-          ./target/${{ matrix.target }}/release/zoxide.exe
-
+        run: |
+          7z a zoxide-${{ steps.get_version.outputs.value }}-${{ matrix.target }}.zip `
+            CHANGELOG.md LICENSE README.md ./man/ ./contrib/completions/ `
+            ./target/${{ matrix.target }}/release/zoxide.exe
       - name: Upload artifact
         uses: actions/upload-artifact@v3
         with:
@@ -110,9 +95,9 @@ jobs:
             *.deb
             *.tar.gz
             *.zip
-
       - name: Create release
-        if: ${{ github.ref == 'refs/heads/main' && startsWith(github.event.head_commit.message, 'chore(release)') }}
+        if: |
+          ${{ github.ref == 'refs/heads/main' && startsWith(github.event.head_commit.message, 'chore(release)') }}
         uses: softprops/action-gh-release@v1
         with:
           draft: true
diff --git a/install.sh b/install.sh
index 2ba77bb..796c4d9 100755
--- a/install.sh
+++ b/install.sh
@@ -7,7 +7,7 @@
 # extension. Note: Most shells limit `local` to 1 var per line, contra bash.
 
 main() {
-    if [ "$KSH_VERSION" = 'Version JM 93t+ 2010-03-05' ]; then
+    if [ "${KSH_VERSION-}" = 'Version JM 93t+ 2010-03-05' ]; then
         # The version of ksh93 that ships with many illumos systems does not
         # support the "local" extension.  Print a message rather than fail in
         # subtle ways later on:
@@ -18,57 +18,57 @@ main() {
 
     # Detect and print host target triple.
     ensure get_architecture
-    local _arch="$RETVAL"
-    assert_nz "$_arch" "arch"
-    echo "Detected architecture: $_arch"
+    local _arch="${RETVAL}"
+    assert_nz "${_arch}" "arch"
+    echo "Detected architecture: ${_arch}"
 
     # Create and enter a temporary directory.
     local _tmp_dir
     _tmp_dir="$(mktemp -d)" || err "mktemp: could not create temporary directory"
-    cd "$_tmp_dir" || err "cd: failed to enter directory: $_tmp_dir"
+    cd "${_tmp_dir}" || err "cd: failed to enter directory: ${_tmp_dir}"
 
     # Download and extract zoxide.
-    ensure download_zoxide "$_arch"
-    local _package="$RETVAL"
-    assert_nz "$_package" "package"
-    echo "Downloaded package: $_package"
-    case "$_package" in
+    ensure download_zoxide "${_arch}"
+    local _package="${RETVAL}"
+    assert_nz "${_package}" "package"
+    echo "Downloaded package: ${_package}"
+    case "${_package}" in
     *.tar.gz)
         need_cmd tar
-        ensure tar -xf "$_package"
+        ensure tar -xf "${_package}"
         ;;
     *.zip)
         need_cmd unzip
-        ensure unzip -oq "$_package"
+        ensure unzip -oq "${_package}"
         ;;
     *)
-        err "unsupported package format: $_package"
+        err "unsupported package format: ${_package}"
         ;;
     esac
 
     # Install binary.
-    local _bin_dir="$HOME/.local/bin"
+    local _bin_dir="${HOME}/.local/bin"
     local _bin_name
-    case "$_arch" in
+    case "${_arch}" in
     *windows*) _bin_name="zoxide.exe" ;;
     *) _bin_name="zoxide" ;;
     esac
-    ensure mkdir -p "$_bin_dir"
-    ensure cp "$_bin_name" "$_bin_dir"
-    ensure chmod +x "$_bin_dir/$_bin_name"
-    echo "Installed zoxide to $_bin_dir"
+    ensure mkdir -p "${_bin_dir}"
+    ensure cp "${_bin_name}" "${_bin_dir}"
+    ensure chmod +x "${_bin_dir}/${_bin_name}"
+    echo "Installed zoxide to ${_bin_dir}"
 
     # Install manpages.
-    local _man_dir="$HOME/.local/share/man"
-    ensure mkdir -p "$_man_dir/man1"
-    ensure cp "man/man1/"* "$_man_dir/man1/"
-    echo "Installed manpages to $_man_dir"
+    local _man_dir="${HOME}/.local/share/man"
+    ensure mkdir -p "${_man_dir}/man1"
+    ensure cp "man/man1/"* "${_man_dir}/man1/"
+    echo "Installed manpages to ${_man_dir}"
 
     # Print success message and check $PATH.
     echo ""
     echo "zoxide is installed!"
-    if ! echo ":$PATH:" | grep -Fq ":$_bin_dir:"; then
-        echo "NOTE: $_bin_dir is not on your \$PATH. zoxide will not work unless it is added to \$PATH."
+    if ! echo ":${PATH}:" | grep -Fq ":${_bin_dir}:"; then
+        echo "NOTE: ${_bin_dir} is not on your \$PATH. zoxide will not work unless it is added to \$PATH."
     fi
 }
 
@@ -86,33 +86,35 @@ download_zoxide() {
 
     local _releases_url="https://api.github.com/repos/ajeetdsouza/zoxide/releases/latest"
     local _releases
-    case "$_dld" in
-    curl) _releases="$(curl -sL "$_releases_url")" ||
-        err "curl: failed to download $_releases_url" ;;
-    wget) _releases="$(wget -qO- "$_releases_url")" ||
-        err "wget: failed to download $_releases_url" ;;
+    case "${_dld}" in
+    curl) _releases="$(curl -sL "${_releases_url}")" ||
+        err "curl: failed to download ${_releases_url}" ;;
+    wget) _releases="$(wget -qO- "${_releases_url}")" ||
+        err "wget: failed to download ${_releases_url}" ;;
+    *) err "unsupported downloader: ${_dld}" ;;
     esac
-    (echo "$_releases" | grep -q 'API rate limit exceeded') &&
+    (echo "${_releases}" | grep -q 'API rate limit exceeded') &&
         err "you have exceeded GitHub's API rate limit. Please try again later, or use a different installation method: https://github.com/ajeetdsouza/zoxide/#installation"
 
     local _package_url
-    _package_url="$(echo "$_releases" | grep "browser_download_url" | cut -d '"' -f 4 | grep "$_arch")" ||
-        err "zoxide has not yet been packaged for your architecture ($_arch), please file an issue: https://github.com/ajeetdsouza/zoxide/issues"
+    _package_url="$(echo "${_releases}" | grep "browser_download_url" | cut -d '"' -f 4 | grep "${_arch}")" ||
+        err "zoxide has not yet been packaged for your architecture (${_arch}), please file an issue: https://github.com/ajeetdsouza/zoxide/issues"
 
     local _ext
-    case "$_package_url" in
+    case "${_package_url}" in
     *.tar.gz) _ext="tar.gz" ;;
     *.zip) _ext="zip" ;;
-    *) err "unsupported package format: $_package_url" ;;
+    *) err "unsupported package format: ${_package_url}" ;;
     esac
 
-    local _package="zoxide.$_ext"
-    case "$_dld" in
-    curl) _releases="$(curl -sLo "$_package" "$_package_url")" || err "curl: failed to download $_package_url" ;;
-    wget) _releases="$(wget -qO "$_package" "$_package_url")" || err "wget: failed to download $_package_url" ;;
+    local _package="zoxide.${_ext}"
+    case "${_dld}" in
+    curl) _releases="$(curl -sLo "${_package}" "${_package_url}")" || err "curl: failed to download ${_package_url}" ;;
+    wget) _releases="$(wget -qO "${_package}" "${_package_url}")" || err "wget: failed to download ${_package_url}" ;;
+    *) err "unsupported downloader: ${_dld}" ;;
     esac
 
-    RETVAL="$_package"
+    RETVAL="${_package}"
 }
 
 # The below functions have been extracted with minor modifications from the
@@ -126,25 +128,25 @@ get_architecture() {
     _cputype="$(uname -m)"
     _clibtype="musl"
 
-    if [ "$_ostype" = Linux ]; then
-        if [ "$(uname -o)" = Android ]; then
+    if [ "${_ostype}" = Linux ]; then
+        if [ "$(uname -o || true)" = Android ]; then
             _ostype=Android
         fi
     fi
 
-    if [ "$_ostype" = Darwin ] && [ "$_cputype" = i386 ]; then
+    if [ "${_ostype}" = Darwin ] && [ "${_cputype}" = i386 ]; then
         # Darwin `uname -m` lies
         if sysctl hw.optional.x86_64 | grep -q ': 1'; then
             _cputype=x86_64
         fi
     fi
 
-    if [ "$_ostype" = SunOS ]; then
+    if [ "${_ostype}" = SunOS ]; then
         # Both Solaris and illumos presently announce as "SunOS" in "uname -s"
         # so use "uname -o" to disambiguate.  We use the full path to the
         # system uname in case the user has coreutils uname first in PATH,
         # which has historically sometimes printed the wrong value here.
-        if [ "$(/usr/bin/uname -o)" = illumos ]; then
+        if [ "$(/usr/bin/uname -o || true)" = illumos ]; then
             _ostype=illumos
         fi
 
@@ -152,18 +154,18 @@ get_architecture() {
         # machine hardware name; e.g., "i86pc" on both 32- and 64-bit x86
         # systems.  Check for the native (widest) instruction set on the
         # running kernel:
-        if [ "$_cputype" = i86pc ]; then
+        if [ "${_cputype}" = i86pc ]; then
             _cputype="$(isainfo -n)"
         fi
     fi
 
-    case "$_ostype" in
+    case "${_ostype}" in
     Android)
         _ostype=linux-android
         ;;
     Linux)
         check_proc
-        _ostype=unknown-linux-$_clibtype
+        _ostype=unknown-linux-${_clibtype}
         _bitness=$(get_bitness)
         ;;
     FreeBSD)
@@ -185,23 +187,23 @@ get_architecture() {
         _ostype=pc-windows-msvc
         ;;
     *)
-        err "unrecognized OS type: $_ostype"
+        err "unrecognized OS type: ${_ostype}"
         ;;
     esac
 
-    case "$_cputype" in
+    case "${_cputype}" in
     i386 | i486 | i686 | i786 | x86)
         _cputype=i686
         ;;
     xscale | arm)
         _cputype=arm
-        if [ "$_ostype" = "linux-android" ]; then
+        if [ "${_ostype}" = "linux-android" ]; then
             _ostype=linux-androideabi
         fi
         ;;
     armv6l)
         _cputype=arm
-        if [ "$_ostype" = "linux-android" ]; then
+        if [ "${_ostype}" = "linux-android" ]; then
             _ostype=linux-androideabi
         else
             _ostype="${_ostype}eabihf"
@@ -209,7 +211,7 @@ get_architecture() {
         ;;
     armv7l | armv8l)
         _cputype=armv7
-        if [ "$_ostype" = "linux-android" ]; then
+        if [ "${_ostype}" = "linux-android" ]; then
             _ostype=linux-androideabi
         else
             _ostype="${_ostype}eabihf"
@@ -225,7 +227,7 @@ get_architecture() {
         _cputype=$(get_endianness mips '' el)
         ;;
     mips64)
-        if [ "$_bitness" -eq 64 ]; then
+        if [ "${_bitness}" -eq 64 ]; then
             # only n64 ABI is supported for now
             _ostype="${_ostype}abi64"
             _cputype=$(get_endianness mips64 '' el)
@@ -247,13 +249,13 @@ get_architecture() {
         _cputype=riscv64gc
         ;;
     *)
-        err "unknown CPU type: $_cputype"
+        err "unknown CPU type: ${_cputype}"
         ;;
     esac
 
     # Detect 64-bit linux with 32-bit userland
     if [ "${_ostype}" = unknown-linux-musl ] && [ "${_bitness}" -eq 32 ]; then
-        case $_cputype in
+        case ${_cputype} in
         x86_64)
             # 32-bit executable for amd64 = x32
             if is_host_amd64_elf; then {
@@ -271,7 +273,7 @@ get_architecture() {
             ;;
         aarch64)
             _cputype=armv7
-            if [ "$_ostype" = "linux-android" ]; then
+            if [ "${_ostype}" = "linux-android" ]; then
                 _ostype=linux-androideabi
             else
                 _ostype="${_ostype}eabihf"
@@ -280,13 +282,14 @@ get_architecture() {
         riscv64gc)
             err "riscv64 with 32-bit userland unsupported"
             ;;
+        *) ;;
         esac
     fi
 
     # Detect armv7 but without the CPU features Rust needs in that build,
     # and fall back to arm.
     # See https://github.com/rust-lang/rustup.rs/issues/587.
-    if [ "$_ostype" = "unknown-linux-musleabihf" ] && [ "$_cputype" = armv7 ]; then
+    if [ "${_ostype}" = "unknown-linux-musleabihf" ] && [ "${_cputype}" = armv7 ]; then
         if ensure grep '^Features' /proc/cpuinfo | grep -q -v neon; then
             # At least one processor does not have NEON.
             _cputype=arm
@@ -294,7 +297,7 @@ get_architecture() {
     fi
 
     _arch="${_cputype}-${_ostype}"
-    RETVAL="$_arch"
+    RETVAL="${_arch}"
 }
 
 get_bitness() {
@@ -307,9 +310,9 @@ get_bitness() {
     # escape sequences, so we use those.
     local _current_exe_head
     _current_exe_head=$(head -c 5 /proc/self/exe)
-    if [ "$_current_exe_head" = "$(printf '\177ELF\001')" ]; then
+    if [ "${_current_exe_head}" = "$(printf '\177ELF\001')" ]; then
         echo 32
-    elif [ "$_current_exe_head" = "$(printf '\177ELF\002')" ]; then
+    elif [ "${_current_exe_head}" = "$(printf '\177ELF\002')" ]; then
         echo 64
     else
         err "unknown platform bitness"
@@ -327,9 +330,9 @@ get_endianness() {
 
     local _current_exe_endianness
     _current_exe_endianness="$(head -c 6 /proc/self/exe | tail -c 1)"
-    if [ "$_current_exe_endianness" = "$(printf '\001')" ]; then
+    if [ "${_current_exe_endianness}" = "$(printf '\001')" ]; then
         echo "${cputype}${suffix_el}"
-    elif [ "$_current_exe_endianness" = "$(printf '\002')" ]; then
+    elif [ "${_current_exe_endianness}" = "$(printf '\002')" ]; then
         echo "${cputype}${suffix_eb}"
     else
         err "unknown platform endianness"
@@ -344,7 +347,7 @@ is_host_amd64_elf() {
     # but we're interested in it being 0x3E to indicate amd64, or not that.
     local _current_exe_machine
     _current_exe_machine=$(head -c 19 /proc/self/exe | tail -c 1)
-    [ "$_current_exe_machine" = "$(printf '\076')" ]
+    [ "${_current_exe_machine}" = "$(printf '\076')" ]
 }
 
 check_proc() {
diff --git a/justfile b/justfile
index be68681..18309da 100644
--- a/justfile
+++ b/justfile
@@ -5,6 +5,8 @@ default:
 fmt:
     nix-shell --cores 0 --pure --run 'cargo-fmt --all'
     nix-shell --cores 0 --pure --run 'nixfmt -- *.nix'
+    nix-shell --cores 0 --pure --run 'shfmt --indent=4 --language-dialect=posix --simplify --write *.sh'
+    nix-shell --cores 0 --pure --run 'yamlfmt -- .github/workflows/*.yml'
 
 [windows]
 fmt:
@@ -14,11 +16,14 @@ fmt:
 lint:
     nix-shell --cores 0 --pure --run 'cargo-fmt --all --check'
     nix-shell --cores 0 --pure --run 'cargo clippy --all-features --all-targets -- -Dwarnings'
-    nix-shell --cores 0 --pure --run 'nixfmt --check -- ./*.nix'
-    nix-shell --cores 0 --pure --run 'markdownlint ./*.md'
-    nix-shell --cores 0 --pure --run 'mandoc -man -Wall -Tlint -- ./man/man1/*.1'
     nix-shell --cores 0 --pure --run 'cargo msrv verify'
     nix-shell --cores 0 --pure --run 'cargo udeps --all-features --all-targets --workspace'
+    nix-shell --cores 0 --pure --run 'mandoc -man -Wall -Tlint -- man/man1/*.1'
+    nix-shell --cores 0 --pure --run 'markdownlint *.md'
+    nix-shell --cores 0 --pure --run 'nixfmt --check -- *.nix'
+    # nix-shell --cores 0 --pure --run 'shellcheck --enable all *.sh'
+    nix-shell --cores 0 --pure --run 'shfmt --diff --indent=4 --language-dialect=posix --simplify *.sh'
+    nix-shell --cores 0 --pure --run 'yamlfmt -lint -- .github/workflows/*.yml'
 
 [windows]
 lint:
diff --git a/shell.nix b/shell.nix
index f825912..2059f4f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,10 +1,10 @@
 let
-  rust = import (builtins.fetchTarball
-    "https://github.com/oxalica/rust-overlay/archive/9096306d4a1c3adcc8d20f2c9dcaee3dee30d1ad.tar.gz");
   pkgs = import (builtins.fetchTarball
-    "https://github.com/NixOS/nixpkgs/archive/5f902ae769594aaeaf326e8623a48482eeacfe89.tar.gz") {
+    "https://github.com/NixOS/nixpkgs/archive/22a6958f46fd8e14830d02856ff63b1d0e5cc3e4.tar.gz") {
       overlays = [ rust ];
     };
+  rust = import (builtins.fetchTarball
+    "https://github.com/oxalica/rust-overlay/archive/a61fcd9910229d097ffef92b5a2440065e3b64d5.tar.gz");
 
   rust-nightly =
     pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.minimal);
@@ -43,6 +43,7 @@ in pkgs.mkShell {
     pkgs.python3Packages.pylint
     pkgs.shellcheck
     pkgs.shfmt
+    pkgs.yamlfmt
 
     # Dependencies
     pkgs.cacert
diff --git a/src/shell.rs b/src/shell.rs
index 8321546..6237f76 100644
--- a/src/shell.rs
+++ b/src/shell.rs
@@ -85,7 +85,7 @@ mod tests {
         source.push('\n');
 
         Command::new("shfmt")
-            .args(["-d", "-s", "-ln", "bash", "-i", "4", "-ci", "-"])
+            .args(["--diff", "--indent=4", "--language-dialect=bash", "--simplify", "-"])
             .write_stdin(source)
             .assert()
             .success()
@@ -218,7 +218,7 @@ mod tests {
         source.push('\n');
 
         Command::new("shfmt")
-            .args(["-d", "-s", "-ln", "posix", "-i", "4", "-ci", "-"])
+            .args(["--diff", "--indent=4", "--language-dialect=posix", "--simplify", "-"])
             .write_stdin(source)
             .assert()
             .success()