copied diktat.sh from benedikt

diktat-cli/build.gradle.kts

@@ -72,6 +72,7 @@ tasks.register<DefaultTask>("shadowExecutableJar") {
     group = "Distribution"
     dependsOn(tasks.shadowJar)
 
+    val scriptFile = project.file("src/main/script/diktat.sh")
     val shadowJarFile = tasks.shadowJar
         .get()
         .outputs
@@ -81,22 +82,15 @@ tasks.register<DefaultTask>("shadowExecutableJar") {
         .buildDirectory
         .file(shadowJarFile.name.removeSuffix(".jar"))
 
-    inputs.file(shadowJarFile)
+    inputs.files(scriptFile, shadowJarFile)
     outputs.file(outputFile)
 
     doLast {
         outputFile.get()
             .asFile
             .apply {
                 // language=shell script
-                writeText(
-                    """
-                    #!/bin/sh
-
-                    exec java -jar "$0" "$@"
-
-                    """.trimIndent()
-                )
+                writeBytes(scriptFile.readBytes())
                 appendBytes(shadowJarFile.readBytes())
                 setExecutable(true, false)
             }

diktat-cli/src/main/script/diktat.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+#
+# vim:ai et sw=4 si sta ts=4:
+#
+# External variables used:
+#
+# - JAVA_HOME
+# - GITHUB_ACTIONS
+
+# Bash strict mode,
+# see http://redsymbol.net/articles/unofficial-bash-strict-mode/.
+set -euo pipefail
+
+function error() {
+    local message
+    message="$*"
+
+    if [[ "${GITHUB_ACTIONS:=false}" == 'true' ]]
+    then
+        # Echoing to GitHub.
+        echo "::error::${message}"
+    elif [[ -t 1 ]]
+    then
+        # Echoing to a terminal.
+        echo -e "\e[1m$(basename "$0"): \e[31merror:\e[0m ${message}" >&2
+    else
+        # Echoing to a pipe.
+        echo "$(basename "$0"): error: ${message}" >&2
+    fi
+}
+
+# Exit codes.
+# The code of 1 is returned by ktlint in the event of failure.
+declare -ir ERROR_JAVA_NOT_FOUND=2
+declare -ir ERROR_INCOMPATIBLE_BASH_VERSION=8
+
+if (( BASH_VERSINFO[0] < 4 ))
+then
+    error "bash version ${BASH_VERSION} is too old, version 4+ is required"
+    exit ${ERROR_INCOMPATIBLE_BASH_VERSION}
+fi
+
+JAVA_ARGS=()
+DIKTAT_JAR="$0"
+
+# Locates Java, preferring JAVA_HOME.
+#
+# The 1st variable expansion prevents the "unbound variable" error if JAVA_HOME
+# is unset.
+function find_java() {
+    if [[ -n "${JAVA_HOME:=}" ]]
+    then
+        case "$(uname -s)" in
+            'MINGW32_NT-'* | 'MINGW64_NT-'* | 'MSYS_NT-'* )
+                JAVA_HOME="$(cygpath "${JAVA_HOME}")"
+                ;;
+        esac
+
+        JAVA="${JAVA_HOME}/bin/java"
+        # Update the PATH, just in case
+        export PATH="${JAVA_HOME}/bin:${PATH}"
+    elif [[ -x "$(which java 2>/dev/null)" ]]
+    then
+        JAVA="$(which java 2>/dev/null)"
+    else
+        error 'Java is not found'
+        exit ${ERROR_JAVA_NOT_FOUND}
+    fi
+}
+
+# On Windows, converts a UNIX path to Windows. Should be invoked before a path
+# is passed to any of the Windows-native tools (e.g.: `java`).
+#
+# On UNIX, just returns the 1st argument.
+function native_path() {
+    case "$(uname -s)" in
+        'MINGW32_NT-'* | 'MINGW64_NT-'* | 'MSYS_NT-'* )
+            cygpath --windows "$1"
+            ;;
+        *)
+            echo "$1"
+            ;;
+    esac
+}
+
+find_java
+
+JAVA_ARGS+=('-Xmx512m')
+JAVA_ARGS+=('-jar' "$(native_path "${DIKTAT_JAR}")")
+
+exec "${JAVA}" "${JAVA_ARGS[@]}" "$@"