Escaping escape sequence in Python

Question

I am kind of new to python. Goal is to execute a shell command using subprocess parse & retrive the printed output from shell. The execution errors out as shown in the sample output msg below. Also shown below is the sample code snippet

Code snippet:

testStr = "cat tst.txt | grep Location | sed -e '/.*Location: //g' "
print "testStr = "+testStr
testStrOut = subprocess.Popen([testStr],shell=True,stdout=subprocess.PIPE).communicate()[0]

Output:

testStr = cat tst.txt | grep Location | sed -e '/.*Location: //g' 
cat: tst.txt: No such file or directory
sed: -e expression #1, char 15: unknown command: `/'

Is there a workaround or a function that could be used ?

Appreciate your help Thanks

give subprocess the full path of the file "tst.txt".

MBarsi
– MBarsi

2011-05-26 09:45:28 +00:00
Commented May 26, 2011 at 9:45 — MBarsi
– MBarsi, Commented May 26, 2011 at 9:45

Speckinius Flecksis · Accepted Answer · 2011-05-26 09:46:25Z

1

I suppose your main error is not python related. To be more precise, there are 3 of them:

You forgot to import subprocess.
It should be sed -e 's/.*Location: //g'. You wrote ///g instead of s///g.
tst.txt does not exist.

answered May 26, 2011 at 9:46

Speckinius Flecksis

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1 Comment

Joe Over a year ago

Thanks- That was one mistake. Found it in the mean time. Also the following link answered to the question on escaping '\r' stackoverflow.com/questions/4392176/escape-for-str-in-python.

Lee D · Accepted Answer · 2011-05-26 10:15:20Z

1

You should be passing testStr directly as the first argument, rather than enclosing it in a list. See subprocess.Popen, the paragraph that starts "On Unix, with shell=True: ...".

answered May 26, 2011 at 10:15

Lee D

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