Initial commit

Dockerfile

@@ -0,0 +1,19 @@
+FROM debian
+
+COPY hello.c /src/
+
+RUN \
+	export DEBIAN_FRONTEND=noninteractive \
+	&& apt update \
+	&& apt install -y gcc \
+	&& ( \
+		cd /src \
+		&& gcc -Wall -o /usr/local/bin/hello hello.c \
+	) \
+	&& apt autoremove -y --purge gcc \
+	&& rm -rf \
+		/var/lib/apt/lists/* \
+		/var/tmp/* \
+		/tmp/*
+
+CMD ["hello"]

alpine/Dockerfile

@@ -0,0 +1,19 @@
+FROM alpine
+
+COPY hello.c /src/
+
+RUN \
+	export DEBIAN_FRONTEND=noninteractive \
+	&& apk add --no-cache --virtual .build-deps \
+		gcc \
+		musl-dev \
+	&& ( \
+		cd /src \
+		&& gcc -Wall -o /usr/local/bin/hello hello.c \
+	) \
+	&& apk del --no-cache .build-deps \
+	&& rm -rf \
+		/var/tmp/* \
+		/tmp/*
+
+CMD ["hello"]

alpine/hello.c

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+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <errno.h>
+
+extern char *program_invocation_name;
+extern char *program_invocation_short_name;
+
+int main() {
+	register struct passwd *pw;
+	register uid_t uid;
+
+	printf("This is %s speaking.\n", program_invocation_name);
+
+	uid = geteuid();
+	pw = getpwuid(uid);
+
+	if (pw)
+	{
+		printf("Hello, %s!\n", pw->pw_name);
+	}
+	else
+	{
+		printf("I don't know your name but your ID is %d!\n", (unsigned) uid);
+	}
+
+	return 0;
+}

hello.c

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+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <errno.h>
+
+extern char *program_invocation_name;
+extern char *program_invocation_short_name;
+
+int main() {
+	register struct passwd *pw;
+	register uid_t uid;
+
+	printf("This is %s speaking.\n", program_invocation_name);
+
+	uid = geteuid();
+	pw = getpwuid(uid);
+
+	if (pw)
+	{
+		printf("Hello, %s!\n", pw->pw_name);
+	}
+	else
+	{
+		printf("I don't know your name but your ID is %d!\n", (unsigned) uid);
+	}
+
+	return 0;
+}