creating an input file and running an external program in python

Question

All,

I wrote a small python program to create a file which is used as an input file to run an external program called srce3d. Here it is:

   fin = open('eff.pwr.template','r')  
   fout = open('eff.pwr','wr')  
   for line in fin:
      if 'li' in line:
        fout.write( line.replace('-2.000000E+00', `-15.0`) )
      else: 
        fout.write(line)
   fin.close
   fout.close    
   os.chmod('eff.pwr',0744)
# call srce3d
   os.system("srce3d -bat -pwr eff.pwr >& junk.out")

This does not work. The input file gets written properly but srce3d complains of an end of file during read. The os.system command works fine with a pre-existing file, without any need to open that file.

Thanks for your help

aviator · Accepted Answer · 2016-05-09 20:33:47Z

4

Firstly you are missing the function calls for close.

 fin.close() ## the round braces () were missing.
 fout.close()

A better way to do the same is using contexts.

    with open('eff.pwr.template','r') as fin, open('eff.pwr','wr') as fout:
       ## do all processing here

answered May 9, 2016 at 20:33

aviator

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Comments

Rushy Panchal · Accepted Answer · 2016-05-09 20:07:25Z

1

You didn't actually close the file – you have to call file.close. So,

fin.close
fout.close

should be

fin.close()
fout.close()

answered May 9, 2016 at 20:07

Rushy Panchal

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