exclude custom post type from running a function

Reorder the logic, and fix the minor syntax error in your appended string:

function add_post_content($content) {
    if ( 'portfolio' == get_post_type() )
        return $content;

    if ( is_single() )
        return $content . '<p>Shortlink: ' . wp_get_shortlink() . '</p>';

    return $content;
}

Related Posts:

  1. How to Arrange PHP Files to Allow for Multiple Types of Pages?
  2. How to set and use global variables? Or why not to use them at all
  3. How to deprecate a function used in a plugin?
  4. How to manually fix the WordPress gallery code using PHP in functions.php?
  5. How to make a image-size selected by default in Media upload – WP v3.5
  6. What is This esc_html_e() i wordpress php?
  7. Error Warning: Declaration of description_walker::start_el after PHP upgrade [duplicate]
  8. How to Add Image to WordPress RSS-Feed with no Plug-in?
  9. Function to return true if current page has child pages
  10. How do I change/modify the_post_thumbnail(); html output?
  11. Mega Menu Walker
  12. start_lvl Ignored in Custom walker_nav_menu
  13. Enforcing password complexity
  14. PHP code in page template vs functions
  15. Apply class to every paragraph that holds image?
  16. Remove “Insert from URL” link in Media upload – WP 3.5
  17. static variable loop not working in WordPress
  18. Cleaning up WordPress to improve performance?
  19. Displaying Logged-In User Name in WordPress Menu
  20. Hide main div if wp_nav_menu is empty
  21. Proper use of Output Buffer
  22. List of all theme customizer control types?
  23. Autoloading in Child Theme
  24. Does My Child-Theme Functions.php Need if{die} Security In It? [duplicate]
  25. Modify previous and next text from pagination links
  26. Allowed memory size of 268435456 bytes exhausted (tried to allocate 7146491840906359738 bytes)
  27. How to add a class to the attachment images
  28. Need help setting default setting value for radio button in theme customizer
  29. How to call a function only once (global variable scope)
  30. Multiple is_page() in page.php
  31. Should I write a PHP function in home.php?
  32. Removing Default Gutenberg Blocks, But Keeping Reusable Block Functionality?
  33. Edit tag cloud widget number
  34. adding a filter to a shortcode?
  35. username_exists() function can’t be access without logging in
  36. Customize default settings on new sites on multisite
  37. Set media upload attachment link to none and hide it in WP v3.5
  38. How can I modify the permalink via a filter?
  39. How to draw media details for Isotope gallery using Photoswipe
  40. How to call a PHP function from Javascript in WordPress
  41. How to automatically apply woocommerce product title to all product images alt tags?
  42. How to store the_title() into a variable to reutrn the value, not just echo it
  43. exclude multiple terms using get_terms() function
  44. Create a global variable for use in all templates
  45. Is it possible to disable a function of a parent theme?
  46. Add Useragent to the body class?
  47. How do I make my function add variables/values to the $post object?
  48. Hide old attachments from wp media library
  49. How to override an unpluggable parent theme function?
  50. PHP – redirect https to http and www to non-www
  51. function_exists call in function.php
  52. How to register images uploaded via FTP in media library?
  53. Fatal error: Call to undefined function plugin_dir_path()
  54. Switching wp_get_sites to get_sites
  55. Check if a menu is empty?
  56. wp_set_object_terms and arrays
  57. WordPress Infinite Scroll without using any plugin
  58. Build a content and excerpt grid loop with paging and options for # of posts
  59. Shortcode putting html such as
  60. How to preserve PHP modifications while upgrading WordPress?
  61. Is it possible to get a theme customizer setting from wp.customize using jquery?
  62. Debugging an error: wp_enqueue_style was called incorrectly
  63. How to log out everywhere else, destroy all sessions “all other devices”?
  64. how to get permalink structure with php
  65. Inserting Gravity Form checkbox values into Advanced Custom Fields [closed]
  66. Change the footer text on the login page
  67. How to remove a metabox from menu editor page?
  68. How do I remove a require_once admin panel from the parent theme from the child theme functions.php?
  69. Should the value of core functions be escaped before outputting?
  70. How to get the registered sidebar’s name by its id?
  71. Remove wp-mediaelement.css from wp_head
  72. How do I get the author’s page url from their ID?
  73. Why is my custom meta box input not saving
  74. add_filter to post-gallery and remove all ‘s?
  75. Dynamic URL to reference custom PHP files
  76. How to correct schedule my event weekly with wp_schedule_event()
  77. Set the transport of the Customizer ‘header_image’ core setting to ‘postMessage’
  78. Calculate percentage of post by category
  79. Can i check if user is doing any ajax request?
  80. the_post_thumbnail() based on the Post ID
  81. How to get the original price of the product in woocommerce?
  82. Displaying post per day
  83. Dynamically change feature image in customiser
  84. How to overwrite youtube embed?
  85. One button to change all settings in theme customizer?
  86. Rewriting search and pagination base
  87. Woocommerce auto cancel On-Hold after X days
  88. Check if page parent has certain template
  89. Counting number of posts in a category and its sub categories and displaying result using shortcode
  90. class=”parent” for wp_list_pages?
  91. Calling a method from functions.php on a click of a button
  92. Enqueue Javascript Correctly for 3.5
  93. Shortcode created to check language not works
  94. How to redirect users to custom lostpassword page?
  95. Change comments form title on a page by page basis
  96. Allow authors to post only in categories they create in WordPress
  97. Creating wordpress user registration form
  98. Hide a menu-item and its submenus and display a ‘Log in’ link if the user is logged out
  99. Add custom image sizes to media uploader
  100. Delete post revisions on post publish