howto: install python3 on fedora

https://developers.redhat.com/blog/2018/08/13/install-python3-rhel/

$ git stash list

$ git stash show (inspect)

$ git stash apply (restore)

$ git reset

$ git add .

Add files to staging area.

$ git commit -m 'committing added changes'

Commit changes with comment
eg. git commit -m 'Alice: fix xyz bug. (ALICE-401)'

$ git branch

Show the name of current branch

$ git checkout -b 'name of new branch'

Create a new branch
eg. git checkout -b 'alice-add-new-feature'

$ git push

git push origin 'alice-add-new-feature'
git push origin 'alice-add-new-feature'--force

$ git reset

unstage all

$ git commit --amend

Changing last commit message.

$ git diff --name-only HEAD~0 HEAD~2

Display the list of files changed between 2 commits.

$ git push --force-with-lease origin branch-name

error: failed to push some refs to 'gitolite@gitlab.grass.corp:p/higgs.git'
http://movingfast.io/articles/git-force-pushing/

Check out one file from master.

$ git checkout -- protobuf/emscentral.proto
$ git checkout origin/master -- protobuf/emscentral.proto

# plugin framework
def start(self):
    """Start tracker engine.
    """
    if not self._loop.is_running():
        LOGGER.info('Run event loop forever')
        threading.Thread(target=self._loop.run_forever).start()

    if not self._is_started:
        self._loop.call_soon_threadsafe(
            asyncio.ensure_future, self._start()
        )
        LOGGER.info("Request progress tracker started")
        self._is_started = True
        return

    if self._is_paused:
        self._is_paused = False
    else:
        LOGGER.warning('Request progress tracker already started')

howto: Print object attributes

class ObjectHelper(object):

    @staticmethod
    def stringify(obj):
        attrs = vars(obj)
        return ', '.join("%s: %s" % item for item in attrs.items())

howto: Search for tab indent

grep -P '\t' config.yaml

In GNU Grep of some versions, searches for the string starting with a quotation mark, followed with "hello", followed with another quotation mark. Makes use of "-P", which turns on Perl regex. In Perl regex, "\x22" stands for a quotation mark, via standing for the character with the hexadecimal ASCII value of 22.

source: https://en.wikibooks.org/wiki/Grep

# waiting for task to complete?  
# haven't tested but its much cleaner...
async def _start(self):
    yield from event_loop.call_soon(...)

How-to: wait for processes to complete?

https://docs.python.org/2/library/multiprocessing.html#multiprocessing.Process.join

for proc in jobs:
    proc.join()

How-to: consolidate results from returned by process?

Use shared variable to communicate:

import multiprocessing

def worker(procnum, return_dict):
    '''worker function'''
    print str(procnum) + ' represent!'
    return_dict[procnum] = procnum


if __name__ == '__main__':
    manager = multiprocessing.Manager()
    return_dict = manager.dict()
    jobs = []
    for i in range(5):
        p = multiprocessing.Process(target=worker, args=(i,return_dict))
        jobs.append(p)
        p.start()

    for proc in jobs:
        proc.join()
    print return_dict.values()

source: https://stackoverflow.com/questions/10415028/how-can-i-recover-the-return-value-of-a-function-passed-to-multiprocessing-proce

Official doc

http://pm2.keymetrics.io/docs/usage/startup/

Generate processes for auto-start after reboot

https://futurestud.io/tutorials/pm2-restart-processes-after-system-reboot

Cheatsheet

https://devhints.io/pm2

Install tmux in Centos

$ yum install tmux

Create tmux session with name

$ tmux new -s myname