Conversely, there are a lot of things that are just easier and more straight forward to do in bash, so writing everything in straight python may be more work than it's worth.
Here's a quick posting to describe how you can embed some python code into your bash scripts and get the best of both worlds. Note: just as a heads, up, the examples in this posting are quite contrived.
Calling python from bash is easy. You simply use python's '-' argument and pipe in your python code. I typically wrap my python code in a bash function.
#!/bin/bash
function current_datetime {
python - <<END
import datetime
print datetime.datetime.now()
END
}
# Call it
current_datetime
# Call it and capture the output
DT=$(current_datetime)
echo Current date and time: $DT
You can also pass data into your embedded python script. I do that using environment variables:
#!/bin/bash
function line {
PYTHON_ARG="$1" python - <<END
import os
line_len = int(os.environ['PYTHON_ARG'])
print '-' * line_len
END
}
# Do it one way
line 80
echo 'Handy'
# Do it another way
echo $(line 80)
My usual use-case for doing this is if I'm extending someone else's bash scripts and have to 'go off the reservation' a bit. Sometimes I'm updating an existing 'legacy' script and need to look up some data... maybe do a REST call or something. Here's an example bash script that uses curl to call a REST service to get some weather data. Then is passes the raw JSON response to an embedded python script to interpret and format the results:
#!/bin/bash
function format_weather_data() {
PYTHON_ARG="$1" python - <<END
import os
import json
json_data = os.environ['PYTHON_ARG']
data =json.loads(json_data)
lookup = {
'200': 'thunderstorm with light rain',
'201': 'thunderstorm with rain',
'202': 'thunderstorm with heavy rain',
'210': 'light thunderstorm',
'211': 'thunderstorm',
'212': 'heavy thunderstorm',
'221': 'ragged thunderstorm',
'230': 'thunderstorm with light drizzle',
'231': 'thunderstorm with drizzle',
'232': 'thunderstorm with heavy drizzle',
'300': 'light intensity drizzle',
'301': 'drizzle',
'302': 'heavy intensity drizzle',
'310': 'light intensity drizzle rain',
'311': 'drizzle rain',
'312': 'heavy intensity drizzle rain',
'313': 'shower rain and drizzle',
'314': 'heavy shower rain and drizzle',
'321': 'shower drizzle',
'500': 'light rain',
'501': 'moderate rain',
'502': 'heavy intensity rain',
'503': 'very heavy rain',
'504': 'extreme rain',
'511': 'freezing rain',
'520': 'light intensity shower rain',
'521': 'shower rain',
'522': 'heavy intensity shower rain',
'531': 'ragged shower rain',
'600': 'light snow',
'601': 'snow',
'602': 'heavy snow',
'611': 'sleet',
'612': 'shower sleet',
'615': 'light rain and snow',
'616': 'rain and snow',
'620': 'light shower snow',
'621': 'shower snow',
'622': 'heavy shower snow',
'701': 'mist',
'711': 'smoke',
'721': 'haze',
'731': 'sand, dust whirls',
'741': 'fog',
'751': 'sand',
'761': 'dust',
'762': 'volcanic ash',
'771': 'squalls',
'781': 'tornado',
'800': 'clear sky',
'801': 'few clouds',
'802': 'scattered clouds',
'803': 'broken clouds',
'804': 'overcast clouds',
'900': 'tornado',
'901': 'tropical storm',
'902': 'hurricane',
'903': 'cold',
'904': 'hot',
'905': 'windy',
'906': 'hail',
'950': 'setting',
'951': 'calm',
'952': 'light breeze',
'953': 'gentle breeze',
'954': 'moderate breeze',
'955': 'fresh breeze',
'956': 'strong breeze',
'957': 'high wind, near gale',
'958': 'gale',
'959': 'severe gale',
'960': 'storm',
'961': 'violent storm',
'962': 'hurricane',
}
print "Current temperature: %g F" % data['main']['temp']
print "Today's high: %g F" % data['main']['temp_max']
print "Today's low: %g F" % data['main']['temp_min']
print "Wind speed: %g mi/hr" % data['wind']['speed']
weather_descs = [lookup.get(str(i['id']), '*error*') for i in data['weather']]
print "Weather: %s" % ', '.join(weather_descs)
END
}
WEATHER_URL="http://api.openweathermap.org/data/2.5/weather?q=Cincinnati,OH&units=imperial"
format_weather_data "$(curl -s $WEATHER_URL)"
Hope you find this information useful.
