Question

I recently wrote a script that does a sed command, to replace all the occurrences of “string1” with “string2” in a file named “test.txt”.

It looks like this:

sed -i 's/string1/string2/g' test.txt

The catch is, “string1” does not necessarily exist in test.txt.

I notice after executing a bunch of these sed commands, I get a number of empty files, left behind in the directory, with names that look like this:

“sed4l4DpD”

Does anyone know why this might be, and how I can correct it?

Answer 1

So after much testing last night, it turns out that sed was creating these files when trying to operate on an empty string. The way i was getting the array of “$string1” arguments was through a grep command, which seems to be malformed. What I wanted from the grep was all lines containing something of the type “Text here ‘.'”.

For example the string, “Text here 'ABC.DEF'” in a file, should have been caught by grep, then the ABC.DEF portion of the string, would be substituted by ABC_DEF. Unfortunately the grep I was using would catch lines of the type “Text here ''” (that is, nothing between the ”). When later on, the script attempted to perform a sed replacement using this empty string, the random file was created (probably because sed died).

Thanks for all your help in understanding how sed works.