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Python Virtual Environments

Using virtualenv

$ pip install virtualenv
$ virtualenv --version
# Creating env
$ virtualenv [--no-site-packages] [--python=/usr/bin/python2.7] env-name  
$ lsvirtualenv

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Checkout Latest Commit Before a given Date/Deadline

If you need to checkout the latest commit before a given date or deadline in a git repository:

First, save the desired deadline (yymmddhhmm) an environment variable:

export DEADLINE="2111081100" #yymmddhhmm

Second, run this command to checkout the lates commit before the defined deadline:

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Cron-Job creation in cPanel

Command for Automated MySQL DB Backup

mysqldump --triggers --routines --events --tz-utc \
          -u<user> -p<pass> <db-name> | \ 
          gzip -9 > /full/path/to/backup/folder/`date +"\%Y-\%m-\%d-\%H\%M"`_my_db.sql.gz

• The date format parameters must be escaped as %

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Configuring DNS Service (dnsmasq) for macOS

1. Installing dnsmasq

$ brew update && brew upgrade
$ brew install dnsmasq
# defaults to: /usr/local/etc
$ mkdir -pv $(brew --prefix)/etc/
$ sudo mkdir -v /etc/resolver

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RSync Commands CheatSheet

$ rsync --zaP src/ dst
$ rsync --zaP -e 'ssh -p <port-number>' src/ dst
$ rsync --anv src/ dst
$ rsync --delete
$ rsync --exclude=pattern
$ rsync --exclude=p --include=p

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mysqldump Tips

CLI command format

$ mysqldump <mysqldump options> [<dbname1> <dbname2> ...] [> outputfile.sql]

CLI Options

• --all-databases

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VI/VIM Commands, Configuration, Tricks

Display whitespace characters as visible characters

:set list
:set listchars=eol:⏎,tab:▸·,trail:␠,nbsp:⎵

Ref: https://vi.stackexchange.com/questions/422/displaying-tabs-as-characters

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Create Bootable USB stick form ISO in MacOS

Convert ISO to UDRW format

$ hdiutil convert -format UDRW -o destination_file.img source_file.iso

Prepare USB stick

1. Find usb stick device file

$ diskutil list

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String Formatting & Substitution in Python

Method-1

data = {'unit': 'celsius', 'value':20}
"The temperature in %(unit)s is %(value)f degrees" % data

Method-2

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Plotting Histograms in Python

Using MatPlotLib API

Example 1:

s = np.random.uniform(-1,0,1000)
import matplotlib.pyplot as plt
count, bins, ignored = plt.hist(s, 15, normed=True)
plt.plot(bins, np.ones_like(bins), linewidth=2, color='r')