Add support for `--silent` to `nvm run` and `nvm exec`.

Fixes #842.

nvm.sh

@@ -1285,8 +1285,8 @@ nvm() {
       echo '    --reinstall-packages-from=<version>     When installing, reinstall packages installed in <node|iojs|node version number>'
       echo '  nvm uninstall <version>                   Uninstall a version'
       echo '  nvm use [--silent] <version>              Modify PATH to use <version>. Uses .nvmrc if available'
-      echo '  nvm exec <version> [<command>]        Run <command> on <version>. Uses .nvmrc if available for <version>'
+      echo '  nvm exec [--silent] <version> [<command>] Run <command> on <version>. Uses .nvmrc if available'
-      echo '  nvm run <version> [<args>]            Run `node` on <version> with <args> as arguments. Uses .nvmrc if available for <version>'
+      echo '  nvm run [--silent] <version> [<args>]     Run `node` on <version> with <args> as arguments. Uses .nvmrc if available'
       echo '  nvm current                               Display currently activated version'
       echo '  nvm ls                                    List installed versions'
       echo '  nvm ls <version>                          List versions matching a given description'
@@ -1659,6 +1659,14 @@ nvm() {
       has_checked_nvmrc=0
       # run given version of node
       shift
+
+      local NVM_SILENT
+      NVM_SILENT=0
+      if [ "_$1" = "_--silent" ]; then
+        NVM_SILENT=1
+        shift
+      fi
+
       if [ $# -lt 1 ]; then
         nvm_rc_version && has_checked_nvmrc=1
         if [ -n "$NVM_RC_VERSION" ]; then
@@ -1713,11 +1721,11 @@ nvm() {
         fi
         EXIT_CODE="$?"
       elif [ "$NVM_IOJS" = true ]; then
-        echo "Running io.js $(nvm_strip_iojs_prefix "$VERSION")$(nvm_print_npm_version)"
+        [ $NVM_SILENT -eq 1 ] || echo "Running io.js $(nvm_strip_iojs_prefix "$VERSION")$(nvm_print_npm_version)"
         OUTPUT="$(nvm use "$VERSION" >/dev/null && iojs $ARGS)"
         EXIT_CODE="$?"
       else
-        echo "Running node $VERSION$(nvm_print_npm_version)"
+        [ $NVM_SILENT -eq 1 ] || echo "Running node $VERSION$(nvm_print_npm_version)"
         OUTPUT="$(nvm use "$VERSION" >/dev/null && node $ARGS)"
         EXIT_CODE="$?"
       fi
@@ -1732,6 +1740,13 @@ nvm() {
     "exec" )
       shift
 
+      local NVM_SILENT
+      NVM_SILENT=0
+      if [ "_$1" = "_--silent" ]; then
+        NVM_SILENT=1
+        shift
+      fi
+
       local provided_version
       provided_version="$1"
       if [ -n "$provided_version" ]; then
@@ -1751,7 +1766,7 @@ nvm() {
         return $EXIT_CODE
       fi
 
-      echo "Running node $VERSION$(nvm_print_npm_version)"
+      [ $NVM_SILENT -eq 1 ] || echo "Running node $VERSION$(nvm_print_npm_version)"
       NODE_VERSION="$VERSION" $NVM_DIR/nvm-exec "$@"
     ;;
     "ls" | "list" )