Add redis symlinks at the same place as the installed binaries (#193)

Adds a new make variable called `USE_REDIS_SYMLINKS`, with default value
`yes`. If yes, then `make install` creates additional symlinks to the
installed binaries:

* `valkey-server`
* `valkey-cli`
* `valkey-benchmark`
* `valkey-check-rdb`
* `valkey-check-aof`
* `valkey-sentinel`

The names of the symlinks are the legacy redis binary names
(`redis-server`, etc.). The purpose is to provide backward compatibility
for scripts expecting the these filenames. The symlinks are installed in
the same directory as the binaries (typically `/usr/local/bin/` or
similar).

Similarly, `make uninstall` removes these symlinks if
`USE_REDIS_SYMLINKS` is `yes`.

This is described in a note in README.md.

Fixes #147

---------

Signed-off-by: Vitah Lin <vitahlin@gmail.com>
Co-authored-by: Madelyn Olson <34459052+madolson@users.noreply.github.com>

README.md

@@ -196,6 +196,11 @@ In order to install Redis binaries into /usr/local/bin, just use:
 You can use `make PREFIX=/some/other/directory install` if you wish to use a
 different destination.
 
+_Note_: For compatibility with Redis, we create symlinks from the Redis names (`redis-server`, `redis-cli`, etc.) to the Valkey binaries installed by `make install`.
+The symlinks are created in same directory as the Valkey binaries.
+The symlinks are removed when using `make uninstall`.
+The creation of the symlinks can be skipped by setting the makefile variable `USE_REDIS_SYMLINKS=no`.
+
 `make install` will just install binaries in your system, but will not configure
 init scripts and configuration files in the appropriate place. This is not
 needed if you just want to play a bit with Redis, but if you are installing

src/Makefile

@@ -319,10 +319,33 @@ ifndef V
         @printf '    %b %b\n' $(LINKCOLOR)INSTALL$(ENDCOLOR) $(BINCOLOR)$(1)$(ENDCOLOR) 1>&2
         @$(INSTALL) $(1) $(2)
     endef
+
+    define INSTALL_REDIS_SYMLINK
+        @printf '    %b %b %b %b %b %b %b\n' \
+        $(LINKCOLOR)INSTALL SYMLINK$(ENDCOLOR) \
+        $(BINCOLOR)$(subst $(ENGINE_NAME),redis,$(1))$(ENDCOLOR) -\> $(BINCOLOR)$(1)$(ENDCOLOR) 1>&2
+        @ln -sf $(1) $(2)/$(subst $(ENGINE_NAME),redis,$(1))
+    endef
 else
     define MAKE_INSTALL
         $(INSTALL) $(1) $(2)
     endef
+
+    define INSTALL_REDIS_SYMLINK
+        ln -sf $(1) $(2)/$(subst $(ENGINE_NAME),redis,$(1))
+    endef
+endif
+
+# Determine install/unstall Redis symlinks for compatibility when 
+# installing/uninstalling Valkey binaries (defaulting to `yes`)
+USE_REDIS_SYMLINKS?=yes
+ifeq ($(USE_REDIS_SYMLINKS),yes)
+	MAYBE_INSTALL_REDIS_SYMLINK=$(INSTALL_REDIS_SYMLINK)
+	MAYBE_UNINSTALL_REDIS_SYMLINK=@rm -f $(1)/$(subst $(ENGINE_NAME),redis,$(2))
+	FINAL_CFLAGS+= -DUSE_REDIS_SYMLINKS
+else
+	MAYBE_INSTALL_REDIS_SYMLINK=
+	MAYBE_UNINSTALL_REDIS_SYMLINK=
 endif
 
 REDIS_CC=$(QUIET_CC)$(CC) $(FINAL_CFLAGS)
@@ -517,6 +540,18 @@ install: all
 	@ln -sf $(REDIS_SERVER_NAME) $(INSTALL_BIN)/$(REDIS_CHECK_RDB_NAME)
 	@ln -sf $(REDIS_SERVER_NAME) $(INSTALL_BIN)/$(REDIS_CHECK_AOF_NAME)
 	@ln -sf $(REDIS_SERVER_NAME) $(INSTALL_BIN)/$(REDIS_SENTINEL_NAME)
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_SERVER_NAME),$(INSTALL_BIN))
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_CLI_NAME),$(INSTALL_BIN))
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_BENCHMARK_NAME),$(INSTALL_BIN))
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_CHECK_RDB_NAME),$(INSTALL_BIN))
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_CHECK_AOF_NAME),$(INSTALL_BIN))
+	$(call MAYBE_INSTALL_REDIS_SYMLINK,$(REDIS_SENTINEL_NAME),$(INSTALL_BIN))
 
 uninstall:
 	rm -f $(INSTALL_BIN)/{$(REDIS_SERVER_NAME),$(REDIS_BENCHMARK_NAME),$(REDIS_CLI_NAME),$(REDIS_CHECK_RDB_NAME),$(REDIS_CHECK_AOF_NAME),$(REDIS_SENTINEL_NAME)}
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_SERVER_NAME))
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_CLI_NAME))
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_BENCHMARK_NAME))
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_CHECK_RDB_NAME))
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_CHECK_AOF_NAME))
+	$(call MAYBE_UNINSTALL_REDIS_SYMLINK,$(INSTALL_BIN),$(REDIS_SENTINEL_NAME))

src/server.c

@@ -7138,6 +7138,16 @@ int main(int argc, char **argv) {
     else if (strstr(exec_name,"valkey-check-aof") != NULL)
         redis_check_aof_main(argc,argv);
     
+    /* If enable USE_REDIS_SYMLINKS, valkey may install symlinks like 
+     * redis-server -> valkey-server, redis-check-rdb -> valkey-check-rdb,
+     * redis-check-aof -> valkey-check-aof, etc. */
+#ifdef USE_REDIS_SYMLINKS
+    if (strstr(exec_name,"redis-check-rdb") != NULL)
+        redis_check_rdb_main(argc, argv, NULL);
+    else if (strstr(exec_name,"redis-check-aof") != NULL)
+        redis_check_aof_main(argc,argv);
+#endif
+
     if (argc >= 2) {
         j = 1; /* First option to parse in argv[] */
         sds options = sdsempty();