concatenating string in python

Question

I am converting a command line to a python string. The command line is:

../src/clus -INFILE=../input/tua40.sq -OUTPUT=OUT

The python statement is:

c_dir = '~/prj/clus/'
c_bin = c_dir + 'src/clus'
c_data = c_dir + 'input/tua40.sq'

c = LiveProcess()
c.executable = c_bin
c.cwd = c_dir 
c.cmd = [c.executable] + ['-INFILE=', 'c_data, '-OUTPUT=OUT']

Problem is the c.cmd at the end looks like

~/prj/clus/src/clus -INFILE= ~/prj/clus/input/tua40.sq ...

Not that there is a 'space' after '=' which causes the program to report an error.

How can I concatenate '=' to the path?

Ned Batchelder · Accepted Answer · 2012-02-03 17:50:24Z

6

LiveProcess is expecting an argv-style list of arguments. Where you want to make one argument, you need to provide one string. So use concatenation to make the string:

c.cmd = [c.executable] + ['-INFILE='+c_data, '-OUTPUT=OUT']

Also, no need for the list addition:

c.cmd = [c.executable, '-INFILE='+c_data, '-OUTPUT=OUT']

edited Feb 3, 2012 at 17:50

answered Feb 3, 2012 at 17:42

Ned Batchelder

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Comments

Alpha01 · Accepted Answer · 2012-02-03 17:43:51Z

0

Why don't you just concatenate string like this:

a = 'A'+'B'

then

a == 'AB'

that is in your example

['-INFILE=' + c_data, '-OUTPUT=OUT']

answered Feb 3, 2012 at 17:43

Alpha01

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Daenyth · Accepted Answer · 2012-02-03 17:50:12Z

0

Given that it looks like you're concatenating paths, you should be using os.path.join, not regular string concat.

answered Feb 3, 2012 at 17:50

Daenyth

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score 0 · Accepted Answer · 2012-02-03 17:52:54Z

0

Try this:

c.cmd = [c.executable] + ['-INFILE='+c_data, '-OUTPUT=OUT']

edited Feb 3, 2012 at 17:52

answered Feb 3, 2012 at 17:44

user130076

1 Comment

Ned Batchelder Over a year ago

You've over-concatenated there. "-OUTPUT" needs to start a new element.

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