curl\_slist\_append(3) Library Functions Manual curl\_slist\_append(3)

# [NAME](#NAME)

curl\_slist\_append - add a string to an slist

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
struct curl_slist *curl_slist_append(struct curl_slist *list,


                                     const char *string);
```

# [DESCRIPTION](#DESCRIPTION)

[*curl\_slist\_append(3)*](/man/os/curl/curl_slist_append.3) appends a string to a linked list of strings. The existing **list** should be passed as the first argument and the new list is returned from this function. Pass in NULL in the **list** argument to create a new list. The specified **string** has been appended when this function returns. [*curl\_slist\_append(3)*](/man/os/curl/curl_slist_append.3) copies the string. The **string** argument must be a valid string pointer and cannot be NULL.

The list should be freed (after usage) with [*curl\_slist\_free\_all(3)*](/man/os/curl/curl_slist_free_all.3). Its nodes and pointed content may not be altered outside this function.

# [PROTOCOLS](#PROTOCOLS)

This functionality affects all supported protocols

# [EXAMPLE](#EXAMPLE)

```
int main(void)
{


  CURL *handle = curl_easy_init();


  struct curl_slist *slist = NULL;


  struct curl_slist *temp = NULL;


  slist = curl_slist_append(slist, "pragma:");


  if(!slist)


    return -1;


  temp = curl_slist_append(slist, "Accept:");


  if(!temp) {


    curl_slist_free_all(slist);


    return -1;


  }


  slist = temp;


  curl_easy_setopt(handle, CURLOPT_HTTPHEADER, slist);


  curl_easy_perform(handle);


  curl_slist_free_all(slist); /* free the list again */
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.1

# [RETURN VALUE](#RETURN_VALUE)

A null pointer is returned if anything went wrong, otherwise the new list pointer is returned. To avoid overwriting an existing non-empty list on failure, the new list should be returned to a temporary variable which can be tested for NULL before updating the original list pointer.

# [SEE ALSO](#SEE_ALSO)

[**curl\_slist\_free\_all**(3)](/man/os/curl/curl_slist_free_all.3)

2026-09-24 libcurl

---

Document: curl_slist_append(3) from curl 8.22.0-r3 (Chainguard OS)
Source: https://github.com/curl/curl.git