Feature: add default machine

Add a feature that read and write `.local_settings` (repository level)
and `global_settings` (user level) files to save the default machine.
Add tool/set_settings.sh script to setup the default machine.
In src/configure.py:
    - Change the default of `--machine` to None.
    - Add function `get_machine()` to read the default machine setting.
    - Raise FileNotFoundError if the .config file is not found.
Add `src/.local_settings` to .gitignore.

.gitignore

@@ -14,3 +14,4 @@ GAMER_ExtractProfile
 .vscode
 src/Makefile
 src/Makefile.log
+src/.local_settings

src/configure.py

@@ -29,6 +29,8 @@
 GAMER_CONFIG_DIR  = os.path.join("..", "configs")
 GAMER_MAKE_BASE   = "Makefile_base"
 GAMER_MAKE_OUT    = "Makefile"
+GAMER_LOCAL_SETTING  = ".local_settings"
+GAMER_GLOBAL_SETTING = "~/.config/gamer/global_settings"
 GAMER_DESCRIPTION = "Prepare a customized Makefile for GAMER.\nDefault values are marked by '*'.\nUse -lh to show a detailed help message.\n"
 GAMER_EPILOG      = "2023 Computational Astrophysics Lab, NTU. All rights reserved.\n"
 
@@ -371,8 +373,8 @@ def load_arguments():
 
     # machine config setup
     parser.add_argument( "--machine", type=str, metavar="MACHINE",
-                         default="eureka_intel",
-                         help="Select the MACHINE.config file under ../configs directory.\nChoice: [eureka_intel, YOUR_MACHINE_NAME] => "
+                         default=None,
+                         help="Select the MACHINE.config file under ../configs directory.\nChoice: [eureka_intel, spock_intel, YOUR_MACHINE_NAME, ...] => "
                        )
 
     # A. options of diffierent physical models
@@ -729,8 +731,11 @@ def load_config( config ):
     paths, compilers = {}, {"CXX":"", "CXX_MPI":""}
     flags = {"CXXFLAG":"", "OPENMPFLAG":"", "LIBFLAG":"", "NVCCFLAG_COM":"", "NVCCFLAG_FLU":"", "NVCCFLAG_POT":""}
     gpus  = {"GPU_COMPUTE_CAPABILITY":""}
-    with open( config, 'r') as f:
-        lines = f.readlines()
+    if os.path.isfile( config ):
+        with open( config, 'r') as f:
+            lines = f.readlines()
+    else:
+        raise FileNotFoundError("The config file <%s> does not exist."%(config))
 
     for line in lines:
         temp = list( filter( None, re.split(" |:=|\n", line) ) ) # separate by " " and ":="
@@ -760,6 +765,9 @@ def load_config( config ):
     return paths, compilers, flags, gpus
 
 def set_conditional_defaults( args ):
+    if args['machine'] is None:
+        args['machine'] = get_machine()
+
     if args["unsplit_gravity"] is None:
         args["unsplit_gravity"] = (args["model"] == "HYDRO")
 
@@ -784,6 +792,33 @@ def set_conditional_defaults( args ):
         args["barotropic"] = (args["eos"] == "ISOTHERMAL")
     return args
 
+def get_machine():
+    '''
+    When the `--machine` flag is not given, this function will be called
+    and return the default machine in the following order:
+        1. Read the local setting located at `GAMER_LOCAL_SETTING`.
+        2. Read the global setting located at `GAMER_GLOBAL_SETTING`.
+        3. Fall back to `eureka_intel` for backward compatibility.
+    '''
+    # Check if GAMER_LOCAL_SETTING exists
+    local_setting = GAMER_LOCAL_SETTING
+    if os.path.isfile(local_setting):
+        with open(local_setting, 'r') as f:
+            for line in f:
+                tokens = line.strip().split()
+                if len(tokens) >= 2 and tokens[0] == 'machine_name':
+                    return tokens[1]
+    # Check if GAMER_GLOBAL_SETTING exists
+    global_setting = os.path.expanduser(GAMER_GLOBAL_SETTING)
+    if os.path.isfile(global_setting):
+        with open(global_setting, 'r') as f:
+            for line in f:
+                tokens = line.strip().split()
+                if len(tokens) >= 2 and tokens[0] == 'machine_name':
+                    return tokens[1]
+    # Fall back to `eureka_intel` for backward compatibility
+    return 'eureka_intel'
+
 def set_gpu( gpus, flags, args ):
     gpu_opts = {}
     compute_capability = gpus["GPU_COMPUTE_CAPABILITY"]

tool/set_settings.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+cd "$(dirname "$0")"
+
+show_help() {
+    echo "Usage: $0 [--local | --global] --machine=<name>"
+    echo ""
+    echo "Options:"
+    echo "  --local           Use local settings"
+    echo "  --global          Use global settings"
+    echo "  --machine=<name>  Specify the machine name"
+    echo "  -h, --help        Show this help message"
+}
+
+# Parse arguments
+LOCAL=false
+GLOBAL=false
+MACHINE=""
+
+while [[ "$#" -gt 0 ]]; do
+    case $1 in
+        --local) LOCAL=true ;;
+        --global) GLOBAL=true ;;
+        --machine=*) MACHINE="${1#*=}" ;;
+        -h|--help) show_help; exit 0 ;;
+        --machine) echo "Error: Use --machine=<name> to specify the machine."; exit 1 ;;
+        *) echo "Unknown parameter passed: $1"; echo "Use -h or --help for usage information."; exit 1 ;;
+    esac
+    shift
+done
+
+if [ -z "$MACHINE" ]; then
+    echo "Error: --machine option is required."
+    exit 1
+fi
+
+if [ "$LOCAL" = true ] && [ "$GLOBAL" = true ]; then
+    echo "Error: Cannot specify both --local and --global."
+    exit 1
+elif [ "$LOCAL" = true ]; then
+    SETTING_FILE="../src/.local_settings"
+    SETTING_TYPE="local"
+elif [ "$GLOBAL" = true ]; then
+    SETTING_FILE="$HOME/.config/gamer/global_settings"
+    SETTING_TYPE="global"
+else
+    echo "Error: Specify either --local or --global."
+    exit 1
+fi
+
+mkdir -p "$(dirname "$SETTING_FILE")"
+
+# Write the machine name to the setting file
+echo "# GAMER setting file" > "$SETTING_FILE"
+echo "machine_name          $MACHINE" >> "$SETTING_FILE"
+
+# Check if the write was successful
+if [ $? -ne 0 ]; then
+    echo "Error: Failed to write to $SETTING_FILE."
+    exit 1
+fi
+
+echo "Successfully wrote $SETTING_TYPE settings to $SETTING_FILE for machine='$MACHINE'."