cannot find -lcurl

I'm so confused by this. I'm trying to follow this curl example and get it to compile:

https://github.com/curl/curl/blob/master/docs/examples/smtp-mail.c

https://github.com/curl/curl/blob/master/docs/examples/Makefile.example

And what I have so far is borderline copy/pasted, but I keep getting an error "cannot find -lcurl"

This is what I have for the code:

#include <stdio.h>
#include <string.h>
#include "curl-7.64.0/include/curl/curl.h"

/*
 * For an SMTP example using the multi interface please see smtp-multi.c.
 */ 

/* The libcurl options want plain addresses, the viewable headers in the mail
 * can very well get a full name as well.
 */ 
#define FROM_ADDR    "<sender@example.org>"
#define TO_ADDR      "<addressee@example.net>"
#define CC_ADDR      "<info@example.org>"

#define FROM_MAIL "Sender Person " FROM_ADDR
#define TO_MAIL   "A Receiver " TO_ADDR
#define CC_MAIL   "John CC Smith " CC_ADDR

static const char *payload_text[] = {
  "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n",
  "To: " TO_MAIL "\r\n",
  "From: " FROM_MAIL "\r\n",
  "Cc: " CC_MAIL "\r\n",
  "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
  "rfcpedant.example.org>\r\n",
  "Subject: SMTP example message\r\n",
  "\r\n", /* empty line to divide headers from body, see RFC5322 */ 
  "The body of the message starts here.\r\n",
  "\r\n",
  "It could be a lot of lines, could be MIME encoded, whatever.\r\n",
  "Check RFC5322.\r\n",
  NULL
};

struct upload_status {
  int lines_read;
};

static size_t payload_source(void *ptr, size_t size, size_t nmemb, void *userp)
{
  struct upload_status *upload_ctx = (struct upload_status *)userp;
  const char *data;

  if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
    return 0;
  }

  data = payload_text[upload_ctx->lines_read];

  if(data) {
    size_t len = strlen(data);
    memcpy(ptr, data, len);
    upload_ctx->lines_read++;

    return len;
  }

  return 0;
}

int main(void)
{
  CURL *curl;
  CURLcode res = CURLE_OK;
  struct curl_slist *recipients = NULL;
  struct upload_status upload_ctx;

  upload_ctx.lines_read = 0;

  curl = curl_easy_init();
  if(curl) {
    /* This is the URL for your mailserver */ 
    curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com");

    /* Note that this option isn't strictly required, omitting it will result
     * in libcurl sending the MAIL FROM command with empty sender data. All
     * autoresponses should have an empty reverse-path, and should be directed
     * to the address in the reverse-path which triggered them. Otherwise,
     * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
     * details.
     */ 
    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM_ADDR);

    /* Add two recipients, in this particular case they correspond to the
     * To: and Cc: addressees in the header, but they could be any kind of
     * recipient. */ 
    recipients = curl_slist_append(recipients, TO_ADDR);
    recipients = curl_slist_append(recipients, CC_ADDR);
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);

    /* We're using a callback function to specify the payload (the headers and
     * body of the message). You could just use the CURLOPT_READDATA option to
     * specify a FILE pointer to read from. */ 
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
    curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* Send the message */ 
    res = curl_easy_perform(curl);

    /* Check for errors */ 
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));

    /* Free the list of recipients */ 
    curl_slist_free_all(recipients);

    /* curl won't send the QUIT command until you call cleanup, so you should
     * be able to re-use this connection for additional messages (setting
     * CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT as required, and calling
     * curl_easy_perform() again. It may not be a good idea to keep the
     * connection open for a very long time though (more than a few minutes
     * may result in the server timing out the connection), and you do want to
     * clean up in the end.
     */ 
    curl_easy_cleanup(curl);
  }

  return (int)res;
}

And this is what I'm using for the makefile:

TARGET = email
OBJS= smtp-mail.o
CC = gcc
CFLAGS = -c -g
LDFLAGS = -L/curl-7.64.0/lib
LIBS = -lcurl -lsocket -lnsl -lssl -lcrypto
$(TARGET) : $(OBJS)
$(CC)  -o $(TARGET) $(OBJS) $(LDFLAGS) $(LIBS)
    
smtp-mail.o : smtp-mail.c
    $(CC) $(CFLAGS) $<

Does anyone know why this would be happening?

Last edited on

dutch (2548)

If you want help you need to read what people say and answer their questions.
Is the system you are on some kind of secret?
If not, then what is it? ("Linux" is not specific enough.)
Did you execute an install command from the command line?
E.g., on ubuntu, you would say: sudo apt-get install libcurl4-openssl-dev

Monzaku (26)

Ubuntu 18.04. I did not execute an install command, I don't have access to sudo. I just installed the tar.gz file here:

https://curl.haxx.se/download.html

And then untarred it.

salem c (3698)

> I don't have access to sudo.
So if you asked your sys admin nicely, would they install it for you?

Or are you trying to fly under the wire by trying to do something you really shouldn't be doing?

Monzaku (26)

I have no idea who the admin is. This is for a school project.

salem c (3698)

Well a good place to start would be to go ask the person who set the assignment.
Outline your solution approach and ask how to get libcurl installed.

Everyone with the same assignment is going to have the same problem - no libcurl installed.

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cannot find -lcurl