escaping single quotes in sed

Question

In a file test.py which reads:

#!/usr/bin/env python

import os
import glob

for f in glob.glob('*.txt'):
    print f

...I'd like to programatically replace:

glob.glob('*.txt')

... with:

glob.glob('*.txt')+glob.glob('*.dat') using sed.

I have tried:

sed -i "s,glob.glob('*.txt'),glob.glob('*.txt')+glob.glob('*.dat'),g" test.py

...however this does not replace the string. I have a hunch that this has to do with the use of single quotes in the string to replace and/or the interpretation of the various quotation marks in the shell itself (bash). What is going wrong?

If you have more than one place where the substitution needs to be made (if not, why not just do it by hand?), you should define a wrapper function around the call to `glob` so that there *is* only one place to change. — chepner, Mar 22 '17 at 13:26

score 2 · Accepted Answer · answered Mar 22 '17 at 10:11

You need to escape all special regex meta characters such as . or * in search pattern.

You can use double quotes in sed command. Also use & in replacement to avoid repeating matched text again.

sed "s/glob\.glob('\*\.txt')/&+glob.glob('*.dat')/" test.py

#!/usr/bin/env python

import os
import glob

for f in glob.glob('*.txt')+glob.glob('*.dat'):
    print f

escaping single quotes in sed

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