Include variable in text string in Python

Question

I am trying to include the date in the name of a file. I'm using a variable called 'today'.

When I'm using bash I can reference a variable in a long string of text like this:

today=$(date +"%m-%d-%y")
output_dir="output_files/aws_volumes_list"
ofile="$output_dir"/aws-master-ebs-volumes-list-$today.csv

How can I achieve the same thing in python? I tried to do this, but it didn't work:

today = datetime.today()
today = today.strftime("%B %d %Y")
output_file = '../../../output_files/aws_instance_list/aws-master-list-'today'.csv'

I tried keeping the today variable out of the path by using single quotes.

How can I include the date in the name of the file that I'm creating when using Python?

scomes · Accepted Answer · 2019-03-07 22:34:52Z

3

You can add the strings together or use string formatting

output_file = '../../../output_files/aws_instance_list/aws-master-list-' + today + '.csv'
output_file = '../../../output_files/aws_instance_list/aws-master-list-{0}.csv'.format(today)
output_file = f'../../../output_files/aws_instance_list/aws-master-list-{today}.csv'

The last one will only work in Python >= 3.6

edited Mar 7, 2019 at 22:34

answered Mar 7, 2019 at 22:25

scomes

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Comments

Parzibyte · Accepted Answer · 2019-03-07 22:25:57Z

1

In Python you use + to concat variables.

today = datetime.today()
today = today.strftime("%B %d %Y")
output_file = '../../../output_files/aws_instance_list/aws-master-list-' + today +'.csv'

answered Mar 7, 2019 at 22:25

Parzibyte

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OSainz · Accepted Answer · 2019-03-07 22:29:11Z

1

Give a look to: Python String Formatting Best Practices

answered Mar 7, 2019 at 22:29

OSainz

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Richard Lenkiewicz · Accepted Answer · 2019-03-07 22:31:54Z

1

Not quite sure if thats what you mean, but in python you can either simply add the strings together

new_string=str1+ str2

or something like

new_string='some/location/path/etc/{}/etc//'.format(another_string)

answered Mar 7, 2019 at 22:31

Richard Lenkiewicz

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BoarGules · Accepted Answer · 2019-03-07 22:33:54Z

1

The closest Python equivalent to bash's

ofile="$output_dir"/aws-master-ebs-volumes-list-$today.csv

is

ofile=f'"{output_dir}"/aws-master-ebs-volumes-list-{today}.csv'

Only in Python 3.7 onwards.

answered Mar 7, 2019 at 22:33

BoarGules

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