variable inside a string used as an os command in python

Question

I need to execute a system command in which there is a variable.In the code below

    os.system('SMILExtract -C config/demo/demo1_energy.conf -I user.wav -O csv/user.csv')

in the string "user.wav", user is a variable string and .wav is the constant string.How can include it within the os.system() command

FYI, it is usually better to use subprocess for things like this. It was designed specifically to replace several other, older modules and functions, such as os.system — anon582847382
– anon582847382, Commented Mar 5, 2014 at 16:35

kojiro · Accepted Answer · 2014-03-05 16:34:41Z

3

Use a format string?

os.system('SMILExtract -C config/demo/demo1_energy.conf -I {0}.wav -O csv/user.csv'.format(somevar))

This can be made clean and readable by mapping out the things that can change into various named parameters:

cmd_template = 'SMILExtract -C {config_path} -I {wav_base}.wav -O {csv_path}'
os.system(cmd_template.format(
  config_path='config/demo/demo1_energy.conf',
  wav_base='user',
  csv_path='csv/user.csv',
))

answered Mar 5, 2014 at 16:34

kojiro

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1 Comment

san45 Over a year ago

how to include if both csv path and output path is a variable ?

MattDMo · Accepted Answer · 2014-03-05 16:34:32Z

0

If the variable is named user, just use string concatenation:

os.system('SMILExtract -C config/demo/demo1_energy.conf -I ' + user + '.wav -O csv/user.csv')

answered Mar 5, 2014 at 16:34

MattDMo

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Comments

Trond Kristiansen · Accepted Answer · 2014-03-05 16:40:15Z

0

One way to do this would be to use the call function of the subprocess module:

from subprocess import call
varname="test"
user=varname+str(".wav")
options="-C config/demo/demo1_energy.conf -I %s -O csv/user.csv"%(user)

call(["SMILExtract", options])

answered Mar 5, 2014 at 16:40

Trond Kristiansen

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Comments

Geo Jacob · Accepted Answer · 2014-03-05 16:41:49Z

0

os.system('SMILExtract -C config/demo/demo1_energy.conf -I '+user+'.wav -O csv/user.csv')

answered Mar 5, 2014 at 16:41

Geo Jacob

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