Convert terminal commands to python script

Question

How does one convert this terminal command to python? Here's the code I have tried, and I need some help with it. The values I want to pass in are < | grep "http" > including the file itself, but I get an error for passing in more than one value.

Terminal command: swfdump -a /home/cfc/swf/swf/flash2.swf | grep 'http'

Try 1: dump = Popen(["swfdump", "-a", filename, "|", "grep", "'http'"])

Try 2: dump = check_output(["swfdump", "-a", filename , "| grep 'http'"])

ERROR:

Try 1:

Only one file allowed. You supplied at least two. (/home/cfc/swf/swf/flash2.swf and |)
Only one file allowed. You supplied at least two. (| and grep)
Only one file allowed. You supplied at least two. (grep and 'http')
Couldn't open 'http': No such file or directory
Only one file allowed. You supplied at least two. (/home/cfc/swf/swf/flash2.swf and |)
Only one file allowed. You supplied at least two. (| and grep)
Only one file allowed. You supplied at least two. (grep and 'http')
Couldn't open 'http': No such file or directory

Try 2:

Only one file allowed. You supplied at least two. (/home/cfc/swf/swf/flash2.swf and | grep 'http')
Couldn't open | grep 'http': No such file or directory
Traceback (most recent call last):
File "./SWFFile.py", line 62, in <module>
main()
File "./SWFFile.py", line 61, in main
trid()
File "./SWFFile.py", line 34, in trid
swfDump()
File "./SWFFile.py", line 48, in swfDump
dump = check_output(["swfdump", "-a", filename , "| grep 'http'"] )
File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command '['swfdump', '-a', '/home/cfc/swf/swf/flash2.swf', "| grep 'http'"]' returned non-zero exit status 1

It's an error with the arguments which you are giving to the command tool. Your Python program's okay, it's just the command which you are passing to Popen is flawed. Check it by typing it into the actual shell. — user3917838
– user3917838, Commented Dec 19, 2015 at 5:42
when i run the command in terminal i receive this : Can't parse opcode f8 what does that mean? — Izzy
– Izzy, Commented Dec 19, 2015 at 5:46
I have no idea. That problem is related to your swfdump command. — user3917838
– user3917838, Commented Dec 19, 2015 at 5:48
@PythonGuy Thanks, it turned out to be a problem in the swf file itself, ran it against another file and it worked fine. — Izzy
– Izzy, Commented Dec 20, 2015 at 5:08

tdelaney · Accepted Answer · 2015-12-19 06:16:34Z

1

The pipe command "|" is a shell construct and is meaningless to python. When you execute Popen with a list and without shell=True, the shell is bypassed and the pipe symbol is just passed to the executing program as a command line argument. Confused programs spit out errors in return.

You could run through the shell either by converting the command to a string or by letting python convert the command to a string for you:

dump = Popen("swfdump -a {} | grep 'http'".format(filename),
     shell=True)

dump = Popen(subprocess.list2cmdline(
    ["swfdump", "-a", filename, "|", "grep", "'http'"]),
    shell=True)

Or, do the searching in python itself

proc = Popen(["swfdump", "-a", filename], stdout=subprocess.PIPE)
for line in proc.stdout:
    if 'http' in line:
        print(line.strip())
proc.wait()

answered Dec 19, 2015 at 6:16

tdelaney

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200_success · Accepted Answer · 2015-12-19 10:42:44Z

1

If you are interested in running a lot of external commands from Python, the result is simpler and more readable using the sh module:

from sh import swfdump, grep

grep(swfdump('-a', '/home/cfc/swf/swf/flash2.swf'), 'http')

Note that grepping may be better done using Python than an external command:

from sh import swfdump

for line in swfdump('-a', '/home/cfc/swf/swf/flash2.swf').split('\n'):
    if 'http' in line:
        print(line)

answered Dec 19, 2015 at 10:42

200_success

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