Well this came in very handy.
Pinned: https://askubuntu.com/a/60395
[Cool trick] Shortcut to mkdir and cd to it!
Append following code to /$HOME/.bashrc
function mkdir{
command mkdir $1 && cd $1
}
Then, execute .bashrc
source ~/.bashrc
Using Git bisect to find out when a bug was introduced!
—-Simplified explanation—-
Here’s how to use git bisect , step-by-step!
Step 1: Find a commit where things were working. …
Step 2: Find a commit where things are not working. …
Step 3 – N: Use git bisect to find the problem commit. …
Step 4: Get back to a working state.
Using Git bisect to figure out when brokenness was introduced
Step by step with code.
git log -4 # find previous working commit git checkout #hash git bisect ?
run through previous commits then
git bisect good or bad git checkout #hash
How to ignore files only locally in git?
I have automated tests running everyday, and the issue is that those tests make necessary changes to certain files depending on which test is running. This becomes a problem when I have to report the changes in the repo, as this will report untracked changed, which means I have to ignore certain files such that local Git doesn’t report changes in them specifically.
By making sure to run git update-index --assume-unchanged ./matplotlibrc after making the addition to the exclude file this means changes won’t be picked up until then.
git update-index --assume-unchanged index.rst git update-index --assume-unchanged matplotlibrc
Before:
After:
Changes made but untracked, nice!!!
How can I merge two or more Git commits into one[locally and remote]?
You can do this fairly easily without git rebase or git merge --squash. In this example, we’ll squash the last 3 commits.
If you want to write the new commit message from scratch, this suffices:
git reset --soft HEAD~3 &&
git commit
If you want to start editing the new commit message with a concatenation of the existing commit messages (i.e. similar to what a pick/squash/squash/…/squash git rebase -i instruction list would start you with), then you need to extract those messages and pass them to git commit:
git reset --soft HEAD~3 &&
git commit --edit -m"$(git log --format=%B --reverse HEAD..HEAD@{1})"
Both of those methods squash the last three commits into a single new commit in the same way. The soft reset just re-points HEAD to the last commit that you do not want to squash. Neither the index nor the working tree are touched by the soft reset, leaving the index in the desired state for your new commit (i.e. it already has all the changes from the commits that you are about to “throw away”).
Important: If you’ve already pushed commits to GitHub, and then squash them locally, you will have to force the push to your branch.
$ git push origin branch-name --force
Helpful hint: You can always edit your last commit message, before pushing, by using:
$ git commit --amend
Repurpose Old Smartphones for Home Automation by Turning Sensors into Signals [Paper]
Diagnosing LAN Speeds
After having network issues/degradation while trying to access a work server, I had to diagnose the network the server is connected to. I had to set myself on a mission – and after realising that the seems to be very limited tools for such things, I stumbled upon ‘iperf‘.
Iperf is a command-line tool used in the diagnostics of network speed issues, it measures the maximum network throughput a server can handle. It is particularly useful when experiencing network speed issues, as you can use Iperf to determine which server is unable to reach maximum throughput.
Iperf installation
Iperf must be installed on both computers you are testing the connection between.
sudo apt-get install -y iperf
TCP Clients & Servers
Iperf requires two systems because one system must act as a server, while the other acts as a client. The client connects to the server you’re testing the speed of.
- On the node you wish to test, launch Iperf in server mode:
iperf -s
You should see output similar to:
2. On your second Linode, connect to the first. Replace dbelab04 with the first node’s IP address in my case i’m using the hostname
iperf -c dbelab04
You should see output similar to:
3. You will also see the connection and results on your Iperf server. This will look similar to:
4. To stop the Iperf server process, press CTRL + c.
————————————————————————————————–
You can do pretty much the same thing with plain old nc (netcat) if you’re that way inclined. On the server machine:
nc -vvlnp 12345 >/dev/null
You should see something similar to:
And the client can pipe a 10Gb of zeros through dd over the nc tunnel.
dd if=/dev/zero bs=10M count=1K status=progress | nc -vvn 192.168.4.23 12345
You should see something similar to:
The timing there is given by dd but it should be accurate enough as it can only output as fast the pipe will take it. If you’re unhappy with that you could wrap the whole thing up in a time call.
Remember that the result is in megabytes so multiply it by 8 to get a megabits-per-second speed. The demo above is running at 11.8mbps due to my laptops network limitation and number of hops…
