Shell Programming and Scripting

I'm writing my first script and I have all the other commands I'm using working properly, but I'm having one final issue with a sed. I've looked on the forums for some answers, which have been close but sed is quite confusing to me.

My problem is that I have a file called CylinderAtom1.txt which has a final line that looks like this:

What I wish to do is change the 15.000 to 16.000. My attempts have ranged from error messages to just spitting out a blank file.

Here's an example sed command I've been trying to use:

Code:

sed '$ s/15.000/16.000' <CylinderAtom1.txt >CylinderAtom1.txt

Any help is appreciated!

You cannot write to the same file you are reading from. You would need to do something like this:

Code:

sed 'some sed statements' infile > outfile && mv outfile infile

alternatively, you can use a -i option if you have GNU sed..

Alright, thank you! I got it to run correctly by:

Code:

sed '15059 s/15.000/16.000/' <CylinderAtom1.txt >CylinderAtom2.txt && mv CylinderAtom2.txt CylinderAtom1.txt

Line 15059 is the last line of the file, but I could just change that back to $, correct?

$ means last line, correct... The < redirection from the file is not required and you can leave that out..