feat: allow users to get the principal id of the current identity

src/dfx/src/commands/identity/mod.rs

@@ -6,6 +6,7 @@ use clap::{App, ArgMatches, SubCommand};
 
 mod list;
 mod new;
+mod principal;
 mod remove;
 mod rename;
 mod r#use;
@@ -19,6 +20,7 @@ fn builtins() -> Vec<CliCommand> {
         CliCommand::new(rename::construct(), rename::exec),
         CliCommand::new(r#use::construct(), r#use::exec),
         CliCommand::new(whoami::construct(), whoami::exec),
+        CliCommand::new(principal::construct(), principal::exec),
     ]
 }
 

src/dfx/src/commands/identity/principal.rs

@@ -0,0 +1,16 @@
+use crate::lib::environment::Environment;
+use crate::lib::error::DfxResult;
+use crate::lib::identity::identity_manager::IdentityManager;
+use crate::lib::message::UserMessage;
+use clap::{App, ArgMatches, SubCommand};
+
+pub fn construct() -> App<'static, 'static> {
+    SubCommand::with_name("get-principal-id").about(UserMessage::GetPrincipalId.to_str())
+}
+
+pub fn exec(env: &dyn Environment, _args: &ArgMatches<'_>) -> DfxResult {
+    let identity = IdentityManager::new(env)?.instantiate_selected_identity()?;
+    let principal_id = identity.sender()?;
+    println!("{}", principal_id.to_text());
+    Ok(())
+}

src/dfx/src/lib/message.rs

@@ -126,6 +126,9 @@ user_message!(
     // dfx identity whoami
     ShowIdentity => "Shows the name of the current identity.",
 
+    // dfx identity get-principal-id
+    GetPrincipalId => "Shows the textual representation of the Principal ID associated with the current identity.",
+
     // dfx new
     CreateProject => "Creates a new project.",
     ProjectName => "Specifies the name of the project to create.",