Does cpuminer do its work? I have a question about using cpuminer to mine bitcoins. I know that it's not efficient, but I'm not about making any money from it (obviously), I just want to mine some fractions of a bitcoin.

Now, I have downloaded and compiled it on Ubuntu and then started the program as seen in the output:

 ./minerd --url=stratum+tcp://&lt;server&gt;:3333 --userpass=&lt;username.worker&gt;:&lt;password&gt; --algo=sha256d

[2015-04-26 20:22:45] Starting Stratum on stratum+tcp://&lt;server&gt;:3333
[2015-04-26 20:22:45] Binding thread 2 to cpu 2
[2015-04-26 20:22:45] Binding thread 1 to cpu 1
[2015-04-26 20:22:45] 4 miner threads started, using 'sha256d' algorithm.
[2015-04-26 20:22:45] Binding thread 0 to cpu 0
[2015-04-26 20:22:45] Binding thread 3 to cpu 3
[2015-04-26 20:22:48] thread 3: 2097152 hashes, 1814 khash/s
[2015-04-26 20:22:48] thread 0: 2097152 hashes, 1774 khash/s
[2015-04-26 20:22:48] thread 1: 2097152 hashes, 1742 khash/s
[2015-04-26 20:22:48] thread 2: 2097152 hashes, 1355 khash/s
[2015-04-26 20:23:54] thread 2: 81299404 hashes, 1230 khash/s
[2015-04-26 20:24:05] thread 1: 104547880 hashes, 1354 khash/s
[2015-04-26 20:24:13] thread 3: 108821800 hashes, 1272 khash/s
[2015-04-26 20:24:25] thread 0: 106421736 hashes, 1095 khash/s
[2015-04-26 20:25:01] thread 2: 73787712 hashes, 1102 khash/s
[2015-04-26 20:25:07] thread 1: 81252652 hashes, 1312 khash/s
[2015-04-26 20:25:14] thread 3: 76317796 hashes, 1256 khash/s
[2015-04-26 20:25:27] thread 0: 65677172 hashes, 1051 khash/s
[2015-04-26 20:25:52] thread 2: 66108472 hashes, 1305 khash/s
[2015-04-26 20:26:12] thread 3: 75386708 hashes, 1307 khash/s
[2015-04-26 20:26:15] thread 1: 78701868 hashes, 1152 khash/s
[2015-04-26 20:26:28] thread 0: 63037412 hashes, 1031 khash/s


The problem I have now, is that I never get any output like this:

[&lt;Date&gt;, &lt;Time&gt;] accepted: x/y (x/y%), &lt;bla&gt;khash/s (yay!!!)


and in the mining pool, I dont see my worker online.

I wonder now, if my computer does any work at all, or if it is just too slow and all the work it puts into mining goes to waste.
You are mining, but most pools today have a minimum share difficulty requirement, otherwise very fast miners bombard them with shares that they have to process and discard. For many pools this is at a minimum of 128 or higher, meaning it would take several days for a CPU miner to find a share on average. No pool has a payout of any less than 0.00001 BTC, so there is absolutely no chance of you ever being paid for your work if you are mining using a CPU or GPU at this point in time.