add sysenv command. close #288

core/src/main/java/com/taobao/arthas/core/command/BuiltinCommandPack.java

@@ -6,6 +6,7 @@ import com.taobao.arthas.core.command.basic1000.KeymapCommand;
 import com.taobao.arthas.core.command.basic1000.ResetCommand;
 import com.taobao.arthas.core.command.basic1000.SessionCommand;
 import com.taobao.arthas.core.command.basic1000.ShutdownCommand;
+import com.taobao.arthas.core.command.basic1000.SystemEnvCommand;
 import com.taobao.arthas.core.command.basic1000.SystemPropertyCommand;
 import com.taobao.arthas.core.command.basic1000.VersionCommand;
 import com.taobao.arthas.core.command.hidden.JulyCommand;
@@ -79,6 +80,7 @@ public class BuiltinCommandPack implements CommandResolver {
         commands.add(Command.create(ShutdownCommand.class));
         commands.add(Command.create(SessionCommand.class));
         commands.add(Command.create(SystemPropertyCommand.class));
+        commands.add(Command.create(SystemEnvCommand.class));
         commands.add(Command.create(RedefineCommand.class));
     }
 }

core/src/main/java/com/taobao/arthas/core/command/basic1000/SystemEnvCommand.java

@@ -0,0 +1,77 @@
+package com.taobao.arthas.core.command.basic1000;
+
+import static com.taobao.text.ui.Element.label;
+
+import java.util.Map;
+import java.util.Map.Entry;
+
+import com.taobao.arthas.core.command.Constants;
+import com.taobao.arthas.core.shell.cli.Completion;
+import com.taobao.arthas.core.shell.cli.CompletionUtils;
+import com.taobao.arthas.core.shell.command.AnnotatedCommand;
+import com.taobao.arthas.core.shell.command.CommandProcess;
+import com.taobao.arthas.core.util.StringUtils;
+import com.taobao.middleware.cli.annotations.Argument;
+import com.taobao.middleware.cli.annotations.Description;
+import com.taobao.middleware.cli.annotations.Name;
+import com.taobao.middleware.cli.annotations.Summary;
+import com.taobao.text.Decoration;
+import com.taobao.text.ui.TableElement;
+import com.taobao.text.util.RenderUtil;
+
+/**
+ * @author hengyunabc 2018-11-09
+ *
+ */
+@Name("sysenv")
+@Summary("Display the system env.")
+@Description(Constants.EXAMPLE + "sysenv\n" + "sysenv USER\n" + Constants.WIKI + Constants.WIKI_HOME + "sysenv")
+public class SystemEnvCommand extends AnnotatedCommand {
+
+    private String envName;
+
+    @Argument(index = 0, argName = "env-name", required = false)
+    @Description("env name")
+    public void setOptionName(String envName) {
+        this.envName = envName;
+    }
+
+    @Override
+    public void process(CommandProcess process) {
+        try {
+            if (StringUtils.isBlank(envName)) {
+                // show all system env
+                process.write(renderEnv(System.getenv(), process.width()));
+            } else {
+                // view the specified system env
+                String value = System.getenv(envName);
+                process.write(envName + "=" + value + "\n");
+            }
+        } finally {
+            process.end();
+        }
+    }
+
+    /**
+     * First, try to complete with the sysenv command scope. If completion is
+     * failed, delegates to super class.
+     *
+     * @param completion
+     *            the completion object
+     */
+    @Override
+    public void complete(Completion completion) {
+        CompletionUtils.complete(completion, System.getenv().keySet());
+    }
+
+    private String renderEnv(Map<String, String> envMap, int width) {
+        TableElement table = new TableElement(1, 4).leftCellPadding(1).rightCellPadding(1);
+        table.row(true, label("KEY").style(Decoration.bold.bold()), label("VALUE").style(Decoration.bold.bold()));
+
+        for (Entry<String, String> entry : envMap.entrySet()) {
+            table.row(entry.getKey(), entry.getValue());
+        }
+
+        return RenderUtil.render(table, width);
+    }
+}

core/src/main/java/com/taobao/arthas/core/command/basic1000/SystemPropertyCommand.java

@@ -19,7 +19,6 @@ import java.util.Properties;
 import static com.taobao.text.ui.Element.label;
 
 /**
- * A command to display all the keymap for the specified connection.
  * @author ralf0131 2017-01-09 14:03.
  */
 @Name("sysprop")