show-utils.sh: remove dependency on dirname

.github/workflows/freebsd.yml

@@ -40,8 +40,8 @@ jobs:
         usesh: true
         sync: rsync
         copyback: false
-        # We need jq and GNU coreutils to run show-utils.sh and bash to use inline shell string replacement
-        prepare: pkg install -y rust sudo jaq coreutils bash python3
+        # We need bash to use inline shell string replacement
+        prepare: pkg install -y rust sudo jaq bash python3
         run: |
           ## Prepare, build, and test
           sudo ln -s $(command -v jaq) /usr/local/bin/jq

.github/workflows/openbsd.yml

@@ -41,13 +41,13 @@ jobs:
         sync: rsync
         copyback: false
         mem: 4096
-        # We need jq and GNU coreutils to run show-utils.sh and bash to use inline shell string replacement
+        # We need bash to use inline shell string replacement
         # Use sudo-- to get the default sudo package without ambiguity
         # Install rust and cargo from OpenBSD packages
         prepare: |
           # Clean up disk space before installing packages
           df -h
-          pkg_add curl sudo-- jq coreutils bash rust rust-clippy rust-rustfmt python3
+          pkg_add curl sudo-- jq bash rust rust-clippy rust-rustfmt python3
           rm -rf /usr/share/relink/* /usr/X11R6/* /usr/share/doc/* /usr/share/man/* &
           # Clean up package cache after installation
           pkg_delete -a &

util/show-utils.sh

@@ -3,7 +3,10 @@
 set -eo pipefail
 # spell-checker:ignore (jq) deps startswith
 
-cd -- "$(dirname -- "$0")/.."
+# This script should not depend on external binaries to maximize portability if possible
+dir="${0%/*}"
+[ "$dir" = "$0" ] && dir="."
+cd -- "$dir/.."
 
 # `jq` available?
 if ! jq --version 1>/dev/null 2>&1; then