aaronbbrown / til

A collection of things that I have learned "today."

SSH

• Adding ControlPersist to ~/.ssh/config makes control sockets usable by leaving the socket around for a period if you close the last terminal session. Prevents other sessions from then hanging.

ControlPath /tmp/%r@%h:%p
ControlMaster auto
ControlPersist 10m

Docker

• Restore init in Ubuntu base Docker images so upstart and such runs

FROM ubuntu:12.04
RUN rm /usr/sbin/policy-rc.d; \
    rm /sbin/initctl; dpkg-divert --rename --remove /sbin/initctl

• Remove all exited Docker containers

docker ps -a | grep Exit | cut -d ' ' -f 1 | xargs docker rm

• Get a shell session on the Docker For Mac VM: (Ctrl-A, Ctrl-, "y" to quit)

screen ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty

Linux

• Use prlimit to change ulimits on the fly

prlimit --pid $(pidof mecached) --nofile=8192:8192

Git

• Delete all local branches which have been merged into master

git branch --merged master | grep -v "\* master" | xargs -n 1 git branch -d

• Sign all commits

git config --global commit.gpgsign true

Command line

• urldecode single url from commandline

echo $URL | python -c "import sys, urllib as ul; print ul.unquote_plus(sys.argv[1])"

• urldecode list of urls from the commandline

cat urls | python -c "import sys, urllib as ul; [sys.stdout.write(ul.quote_plus(l)) for l in sys.stdin]"

Shell

• Log everything in a script to both console and syslog

exec 1> >(tee -ai /dev/console | logger -s -t $(basename $0)) 2>&1

Python

• Verify syntax by compiling without executing (similar to ruby -c

python -m py_compile file.py

Go

• Send SIGQUIT & get stack trace w/ Ctrl-\