[bash.bashrc] Add reverse SSH script to bash.bashrc (sonic-net#5438)

* [bash.bashrc] Add reverse SSH script to bash.bashrc
* Fix command issue and add emptt line before EOF
* Add checks for SSH_TARGET_CONSOLE_LINE

Signed-off-by: Jing Kan jika@microsoft.com

Author: Blueve

files/image_config/bash/bash.bashrc

@@ -56,3 +56,20 @@ fi
 
 # Automatically log out console ttyS* sessions after 15 minutes of inactivity
 tty | grep ttyS >/dev/null && TMOUT=900
+
+# if SSH_TARGET_CONSOLE_LINE was set, attach to console line interactive cli directly
+if [ -n "$SSH_TARGET_CONSOLE_LINE" ]; then
+    if [ $SSH_TARGET_CONSOLE_LINE -eq $SSH_TARGET_CONSOLE_LINE 2>/dev/null ]; then
+        # enter the interactive cli
+        connect line $SSH_TARGET_CONSOLE_LINE
+
+        # test exit code, 1 means the console switch feature not enabled
+        if [ $? -ne 1 ]; then
+            # exit after console session ended
+            exit
+        fi
+    else
+        # exit directly when target console line variable is invalid
+        exit
+    fi
+fi