CODEWITHSUNDEEP
pythonbashawksubprocess
Andrej
Andrej

Reputation: 3849

Python subprocess with awk and pipes

I have the following statements in my Python script:

year = '1966'
file = 'test.txt'
cmd = "awk '{FS="|"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc" % (year, file)
bla = run_command(cmd)

where fun_command() is the function:

def run_command(command):                                     
  process = subprocess.Popen([sys.executable, command], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  retcode = process.wait()
  if retcode != 0:
    raise Exception, "Problem running command: " + command
  stdout, stderr = process.communicate()
  return stdout

The following output is produced:

TypeError: unsupported operand type(s) for |: 'str' and 'str'

Any ideas what is wrong?

Upvotes: 2

Views: 1501

Answers (2)

chepner
chepner

Reputation: 531888

sys.executable is the Python interpreter currently running, so you are trying to execute your shell code as Python code. Just use

def run_command(command):                                     
  process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  retcode = process.wait()
  if retcode != 0:
    raise Exception, "Problem running command: " + command
  stdout, stderr = process.communicate()
  return stdout

Upvotes: 1

Teivaz
Teivaz

Reputation: 5675

"awk '{FS="|"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc"
Here you need to escape inner "|"

"awk '{FS=\"|\"}{if ($2 == %s) print $1}' %s | sort -n | uniq | wc"

Upvotes: 3

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