using a shell script within python

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using a shell script within python - Krszt - Oct-10-2018

I want to use a C-shell script within a python program, which works with two arguments.

os.system("recall 20170121 ../E725.txt xy 1")

But I want to use it for a stack, so declared the variables like below, but when I call them within the script it gives an error, that the input file doesn' exist. How can I call the variables?

date_ID=(filename[17:25])
fullpath = '../%s' % (filename)
os.system("import_S1_TOPS_modified $date_ID $fullpath vv 1")

RE: using a shell script within python - volcano63 - Oct-10-2018

(Oct-10-2018, 09:26 AM)Krszt Wrote: I want to use a C-shell script within a python program, which works with two arguments.

os.system("recall 20170121 ../E725.txt xy 1")

But I want to use it for a stack, so declared the variables like below, but when I call them within the script it gives an error, that the input file doesn' exist. How can I call the variables?

date_ID=(filename[17:25])
fullpath = '../%s' % (filename)
os.system("import_S1_TOPS_modified $date_ID $fullpath vv 1")

As far as Python interpreter is concerned, $date_ID and $fullpath in your command line are just string literals within a string. In order to place values within the command string

If you are using version >= 3.6 - modify your string as
```
f"import_S1_TOPS_modified ${date_ID} ${fullpath} vv 1"
```
if not
"import_S1_TOPS_modified ${} ${} vv 1".format(date_ID, fullpath)

RE: using a shell script within python - snippsat - Oct-10-2018

Should not be using os.system(),subprocess replace it a better/safer way.
Ideally is better/safer to pass in a list.

import subprocess

subprocess.run(['ls', '-l'])

Passing in a string has to use shell=True

import subprocess

subprocess.run('ls -l', shell=True)

So as shown bye @volcano63 can pass in using f-string or format(),
but the method with list when shell=False is advisable.

import subprocess

arg = '-l'
subprocess.run(f'ls {arg}', shell=True)

The subprocess has a lot stuff that make it better,even run(that replace call) can now also catch output.

import subprocess

out = subprocess.run(['ls', '-l'], capture_output=True)
print(out.stdout.decode())