Develop Reference

How can I enter "&" into my Java Scanner without getting a (presumed) bash error? [duplicate]

I'm currently having a major issue with a python script. The script runs arbitrary commands through a handler to convert incorrect error reporting into correct error reporting.
The issue I'm having is getting the script to work correctly on windows with a command that contains ampersands in it's path. I've attempted quoting the command, escaping the ampersand with ^ and neither works. I'm now out of ideas. Any suggestions?
To clarify from current responses:
I am using the subprocess module
I am passing the command line + arguments in as a list
The issue is with the path to the command itself, not any of the arguments
I've tried quoting the command. It causes a [Error 123] The filename, directory name, or volume label syntax is incorrect error
I'm using no shell argument (so shell=false)
In case it matters, I'm grabbing a pipe to stderr for processing it, but ignoring stdout and stdin
It is only for use on Windows currently, and works as expected in all other cases that I've tested so far.
The command that is failing is:
p = subprocess.Popen(prog, stderr = subprocess.PIPE, bufsize=-1)
when the first element of the list 'prog' contains any ampersands. Quoting this first string does not work.

Make sure you are using lists and no shell expansion:
subprocess.Popen(['command', 'argument1', 'argument2'], shell=False)

Try quoting the argument that contains the &
wget "http://foo.com/?bar=baz&baz=bar"
Is usually what has to be done in a Linux shell

To answer my own question:
Quoting the actual command when passing the parameters as a list doesn't work correctly (command is first item of list) so to solve the issue I turned the list into a space separated string and passed that into subprocess instead.
Better solutions still welcomed.

"escaping the ampersand with ^"
Are you sure ^ is an escape character to Windows? Shouldn't you use \?

I try a situation as following:
exe = 'C:/Program Files (x86)/VideoLAN/VLC/VLC.exe'
url = 'http://translate.google.com/translate_tts?tl=en&q=hello+world'
subprocess.Popen([exe, url.replace("&","^&")],shell=True)
This does work.

Reading string arguments passed from batch file to python script

I have seen multiple posts on passing the string but not able to find good solution on reading the string passed to python script from batch file. Here is my problem.
I am calling python script from batch file and passing the argument.
string_var = "123_Asdf"
bat 'testscript.py %string_var%'
I have following in my python code.
import sys
passed_var = sys.argv[1]
When I run the above code I always see below error.
passed_var = sys.argv[1]
IndexError: list index out of range
Has anyone seen this issue before? I am only passing string and expect it to be read as part of the first argument I am passing to the script.

Try this:
import sys
for x,parameter in enumerate(sys.argv):
print(x, parameter)

If I have read your question and its formatting correctly, I think your .bat file should read:
Set string_var="123_Asdf"
"D:\BuildTools\tools\python27\python.exe" testscript.py %string_var%
Or better still:
Set "string_var=123_Asdf"
"D:\BuildTools\tools\python27\python.exe" testscript.py "%string_var%"
Where %string_var% can be passed with or without its enclosing doublequotes.

Your batch file should be a bit simpler, make sure you have your PATH set correctly or else this won't work.
python testscript.py [argument]

python: How does subprocess.check_output create it's calls?

I'm trying to read the duration of video files using mediainfo. This shell command works
mediainfo --Inform="Video;%Duration/String3%" file
and produces an output like
00:00:33.600
But when I try to run it in python with this line
subprocess.check_output(['mediainfo', '--Inform="Video;%Duration/String3%"', file])
the whole --Inform thing is ignored and I get the full mediainfo output instead.
Is there a way to see the command constructed by subprocess to see what's wrong?
Or can anybody just tell what's wrong?

Try:
subprocess.check_output(['mediainfo', '--Inform=Video;%Duration/String3%', file])
The " in your python string are likely passed on to mediainfo, which can't parse them and will ignore the option.
These kind of problems are often caused by shell commands requiring/swallowing various special characters. Quotes such as " are often removed by bash due to shell magic. In contrast, python does not require them for magic, and will thus replicate them the way you used them. Why would you use them if you wouldn't need them? (Well, d'uh, because bash makes you believe you need them).
For example, in bash I can do
$ dd of="foobar"
and it will write to a file named foobar, swallowing the quotes.
In python, if I do
subprocess.check_output(["dd", 'of="barfoo"', 'if=foobar'])
it will write to a file named "barfoo", keeping the quotes.

Interpolate variables into external programs call (subprocess.call/Popen) in Python

I'm trying to run an external program from a Python script.
After searching and reading multiple post here I came to what seemed to be the solution.
First, I used subprocess.call function.
If I build the command this way:
hmmer1=subprocess.call("D:\Python_Scripts\HMMer3\hmmsearch.exe --tblout hmmTestTab.out SDHA.hmm Test.fasta")
The external program D:\Python_Scripts\HMMer3\hmmsearch.exe is run taking hmmTestTab.out as file name for the output and SDHA.hmm and Test.fasta as input files.
Nevertheless, if I try to replace the file names with the variables outfile, hmmprofile and fastafile (I intend to receive those variables as arguments for the Python script and use them to build the external program call),
hmmer2=subprocess.call("D:\Python_Scripts\HMMer3\hmmsearch.exe --tblout outfile hmmprofile fastafile")
Python prints an error about being unable to open the input files.
I also used "Popen" function with analogous results:
This call works
hmmer3=Popen(['D:\Python_Scripts\HMMer3\hmmsearch.exe', '--tblout','hmmTestTab.out', 'SDHA.hmm','Test.fasta'])
and this one doesn't
hmmer4=Popen(['D:\Python_Scripts\HMMer3\hmmsearch.exe', '--tblout','outfile', 'hmmprofile','fastafile'])
As result of this, I presume I need to understand which is process to follow to interpolate the variables into the call, because it seems that the problem is there.
Would any of you help me with this issue?
Thanks in advance

You have:
hmmer4=Popen(['D:\Python_Scripts\HMMer3\hmmsearch.exe', '--tblout','outfile', 'hmmprofile','fastafile'])
But that's not passing the variable outfile. It's passing a string, 'outfile'.
You want:
hmmer4=Popen(['D:\Python_Scripts\HMMer3\hmmsearch.exe', '--tblout', outfile, hmmprofile, fastafile])
And the other answer is correct, though it addresses a different problem; you should double the backslashes, or use r'' raw strings.

Try to change this:
hmmer1=subprocess.call("D:\Python_Scripts\HMMer3\hmmsearch.exe"
to
hmmer1=subprocess.call('D:\\Python_Scripts\\HMMer3\\hmmsearch.exe'
Edit
argv = ' --tblout outfile hmmprofile fastafile' # your arguments
program = [r'"D:\\Python_Scripts\\HMMer3\\hmmsearch.exe"', argv]
subprocess.call(program)

Python subprocess issue with ampersands

I'm currently having a major issue with a python script. The script runs arbitrary commands through a handler to convert incorrect error reporting into correct error reporting.
The issue I'm having is getting the script to work correctly on windows with a command that contains ampersands in it's path. I've attempted quoting the command, escaping the ampersand with ^ and neither works. I'm now out of ideas. Any suggestions?
To clarify from current responses:
I am using the subprocess module
I am passing the command line + arguments in as a list
The issue is with the path to the command itself, not any of the arguments
I've tried quoting the command. It causes a [Error 123] The filename, directory name, or volume label syntax is incorrect error
I'm using no shell argument (so shell=false)
In case it matters, I'm grabbing a pipe to stderr for processing it, but ignoring stdout and stdin
It is only for use on Windows currently, and works as expected in all other cases that I've tested so far.
The command that is failing is:
p = subprocess.Popen(prog, stderr = subprocess.PIPE, bufsize=-1)
when the first element of the list 'prog' contains any ampersands. Quoting this first string does not work.

Make sure you are using lists and no shell expansion:
subprocess.Popen(['command', 'argument1', 'argument2'], shell=False)

Try quoting the argument that contains the &
wget "http://foo.com/?bar=baz&baz=bar"
Is usually what has to be done in a Linux shell

To answer my own question:
Quoting the actual command when passing the parameters as a list doesn't work correctly (command is first item of list) so to solve the issue I turned the list into a space separated string and passed that into subprocess instead.
Better solutions still welcomed.

"escaping the ampersand with ^"
Are you sure ^ is an escape character to Windows? Shouldn't you use \?

I try a situation as following:
exe = 'C:/Program Files (x86)/VideoLAN/VLC/VLC.exe'
url = 'http://translate.google.com/translate_tts?tl=en&q=hello+world'
subprocess.Popen([exe, url.replace("&","^&")],shell=True)
This does work.