sed find replace issue

Question

I want to replace

headers['Content-Disposition'] = "attachment; filename=%s" % (filename)

with

headers['Content-Disposition'] = 'attachment; filename="%s"' % (filename)

(so that the "%s" is double-quoted).

My best effort so far is

sed -i -e 's/"headers[\'Content-Disposition\'] = \"attachment\; filename=%s\" % \(filename\)"/"headers[\'Content-Disposition\'] = \'attachment\; filename=\"%s\"\' % \(filename\)"/g' test.txt

but it fails:

sed: -e expression #1, char 33: unterminated `s' command

I tried all that I could come across on stackoverflow and elsewhere. I tried escaping the quotes as well. But this too much of single and double quotes is causing errors.

I have scanned the line and I'm sure I haven't left any unterminated quotes. How can I get it working?

Answer 1

You can avoid "'quoting hell'" by putting your sed commands into a file. Then they are not subject to Bash quoting, and you only have to worry about what's significant to sed:

#!/bin/sed -f

# Adjust this to match as much as you need
/headers\['Content-Disposition'\] = /{

# change all double-quotes to single
y/"/'/
# now double-quote the %s argument
s/%s/"&"/g

}

Answer 2

Try this:

sed -i -e "s/headers\['Content-Disposition'\] = \"attachment; filename=%s\" % (filename)/headers\['Content-Disposition'\] = 'attachment; filename=\"%s\"' % (filename)/g" test.txt

Answer 3

Assuming input is a file that holds the data:

sed "y/\"/'/;s/%s/\"&\"/" input

Answer 4

Although there already is an accepted answer, here is another (a little shorter) variant:

sed -r "s/\"([a-z])/'\1/; s/([a-z])\"/\1'/; s/=([^[:space:]]{2})/\"\1\"/" headers 
headers['Content-Disposition'] = 'attachment; filename"%s"' % (filename)

You could probably make it even more terse, but I choose to split the sed into three distinct parts to make it at least slightly more readable!

---

sed --version
sed (GNU sed) 4.2.2