Centos: No package libssl-dev available

While installing apache on CentOS 7:
No package libssl-dev available

The solution was to install openssl-devel:

yum install openssl-devel


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Best ETH pool March 2018? Mining Pool Hub vs Nanopool vs Ethermine

Watching crypto coin prices plummet, I figure it’s a good time to stay on the most profitable pool while mining is still (barely?) profitable.
These are my results over the 1 week (March 10-17, 2018).

Mining Pool Hub vs Nanopool vs Ethermine
Mining Pool Hub was recommended by a friend for its multi-coin mining + auto-exchange feature, which ideally maximizes profit by mining the most profitable coin and converting it to the coin you want. It’s pretty cool really. I was planning to try mining a variety of coins to hold. But after seeing the results I was getting from ETH, I changed my mind. I think it’s a good pool in many ways (reliable, payouts) but they scored lowest of the 3 in my test. It may very well be that I have something not quite optimized? This was running on ewbf on linux and over 24 hours produced .0233 ETH

Nanopool.org is very popular and has the best graphs (imo) of the 3 here, by far. They also offer ZEC mining, which is nice for Nvidia miners who want to gather some ZEC. They scored well in the test, running on claymore dual miner, 24 hours produced .028 ETH

Ethermine.org was the first pool I tried and the one I’ve used the most. I prefer the graphs to what multi-mining on Mining pool hub provides, but not as nice as Nanopools. The data tends to show up within about 20-30 minutes. Overall it seems to find shares more frequently than nanopool. Running claymore with the same settings as nanopool for 24 hours produced .030 ETH

Notes: 2 rigs with total 15 nvidia cards, mostly 1060 6GB
ubuntu 16.04 running ewbf or claymore dual miner (in mining mode 1)

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error while loading shared libraries: libcudart.so.9.1: cannot open shared object file: No such file or directory

After installing ccminer on Ubuntu, was receiving the subject error.
error while loading shared libraries: libcudart.so.9.1: cannot open shared object file: No such file or directory

Thanks to the folks here I was able to adapt their solution to the current version:
export LD_LIBRARY_PATH=/usr/local/cuda-9.1/lib64:$LD_LIBRARY_PATH
export PATH=/usr/local/cuda-9.1/bin:$PATH

then it works as it should.

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Could NOT find CUDA (missing: CUDA_CUDART_LIBRARY)

Trying to install the nvidia Cuda software as per this site and kept hitting this wall
Could NOT find CUDA (missing: CUDA_CUDART_LIBRARY)

found many possible solutions on the web, but in my case,
cmake -DCUDA_CUDART_LIBRARY=/usr/local/cuda/lib64/libcudart.so ../nheqminer

solved the issue
big thanks to these people!

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Ubuntu USB won’t boot: Resolved

I installed Ubuntu server from a USB stick onto another USB stick. First I tried using a 4GB thumbdrive that was lying around and quickly ran out of space trying to install software, half the drive was used by swap. Then I went with a 16GB drive which has plenty of extra space.

After installing it was up and running great, until I moved the USB drive. Then it would not boot no matter what. Just loads to the bios screen and the boot menu shows this drive as an option but choosing it will not boot.

To fix it, I re-inserted the install USB and chose “install ubuntu” again. Then it gave me some options about the existing system including an option to install grub boot loader. Doing that resolved it.

Seems to be a uefi issue with the mobo (ASUS Z170).

Also not able to get the onboard wifi (“wifi Go”) to work with Ubuntu, but the manual does say it requires windows. darn.

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Update SourceTree password after remote change

After changing my password on the remote, I could not get Sourcetree to log in no matter what. I tried editing and deleting my accounts, deleting and re-adding the repo, nothing was working – Authentication failed every time.

Finally this solution worked for me:

navigating to C:\Users\USERNAME\AppData\Local\Atlassian\SourceTree and removing (or renaming) the passwd file.

Once this file is removed, restart SourceTree and execute a fetch or something else that requires access to the repo in question. SourceTree will then prompt you for your password, rewriting the cached credentials.

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Free Site Sucker with Recursive wget

It may be useful to get an entire website recursively like such:

wget --recursive --page-requisites www.domain.com

More details can be found here about doing this for offline windows use and with no-clobber and other options I wasn’t concerned with.

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CentOS 7 PHP Install : mcrypt.h not found

Received the error while installing PHP:
configure: error: mcrypt.h not found. Please reinstall libmcrypt.

Resolved it with this:
yum install epel-release
yum install libmcrypt-devel

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Google Authenticator on Android, Invalid PIN

2FA is pretty cool, especially when you don’t have to get a text message or email. Google Authenticator generates codes that expire after 30 seconds, so I figured it’s a good option for 2FA. I tried installing it on my Samsung Android and it said it was installing for over 24 hours. Finally I gave in and connected to wifi at which point it installed in a minute or less.

Next issue was invalid PIN. No matter what I tried my PIN was invalid! Then a colleague suggested it’s because my phone’s time is off by a few minutes. Under Settings – System – Date and time – I found that “Automatic date and time” was unchecked. After checking that, my time updated and my Authenticator codes worked right away!

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MongoDB Startup Warnings /sys/kernel/mm/transparent_hugepage/enabled is ‘always’

This happens every time and I need to look for the solution. Posting here to save time going forward.

“startupWarnings”: {
“totalLinesWritten”: 9,
“log”: [
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] “,
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is ‘always’.”,
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] ** We suggest setting it to ‘never'”,
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] “,
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is ‘always’.”,
“2015-08-21T18:47:29.634+0000 I CONTROL [initandlisten] ** We suggest setting it to ‘never'”,


Create the following file at /etc/init.d/disable-transparent-hugepages:

# Provides: disable-transparent-hugepages
# Required-Start: $local_fs
# Required-Stop:
# X-Start-Before: mongod mongodb-mms-automation-agent
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Disable Linux transparent huge pages
# Description: Disable Linux transparent huge pages, to improve
# database performance.

case $1 in
if [ -d /sys/kernel/mm/transparent_hugepage ]; then
elif [ -d /sys/kernel/mm/redhat_transparent_hugepage ]; then
return 0

echo 'never' > ${thp_path}/enabled
echo 'never' > ${thp_path}/defrag

unset thp_path

Make it executable.
Run the following command to ensure that the init script can be used:
sudo chmod 755 /etc/init.d/disable-transparent-hugepages

Configure your operating system to run it on boot.
Use the appropriate command to configure the new init script on your Linux distribution.

Distribution Command
Ubuntu and Debian
sudo update-rc.d disable-transparent-hugepages defaults

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