Seperating variable from immediately following letter

mp85 · 01-10-2012, 06:29 PM

I have a variable $line which i determine earlier in my script.

Now im trying to use sed to insert some text at that specific line number.

This works

Code:

sed '7i\
      blah blah' in.txt' > out.txt

But how do I do this when the 7 is a variable?

Code:

 sed "$linei\
      blah blah' in.txt" > out.txt

How do I tell it that the i is not part of the variable name?

Thanks

unSpawn · 01-10-2012, 06:39 PM

Code:

${line}i

?

schneidz · 01-10-2012, 09:47 PM

sed "$line"i

David the H. · 01-11-2012, 10:01 AM

Unspawn's answer is the best for general use, and schneidz's post leads to a good point; that you can concatenate multiple quoting patterns together:

Code:

sed "$line"'i\
      blah blah' in.txt > out.txt

But there's also simply this:

Code:

sed "$line i\
      blah blah" in.txt > out.txt

sed doesn't care about spaces between commands.

mp85 · 01-11-2012, 01:01 PM

Ended up using the multiquote method.

Thanks

David the H. · 01-12-2012, 06:37 AM

Good. I would've gone with either of the other options myself, as they tend to be easier to read, but it's your choice. If you're satisfied, please mark the thread as solved.

Check out these three links for more on how the shell parses arguments and whitespace. It's a vitally important concept when it comes to scripting.

http://mywiki.wooledge.org/Arguments
http://mywiki.wooledge.org/WordSplitting
http://mywiki.wooledge.org/Quotes