test a sed command?

[Joseph Sinclair]

The default for sed is to output the results to stdout.
If you just leave out the option to write back to the original file, wouldn't that work as a test?
Alternatively you could pipe the sed output into diff against the original file
Something like this:
"sed -e '<command>' infile | diff infile -"


On 09/13/2011 09:00 PM, Dazed_75 wrote:
> How do people test sed replacements on something consequential?  I thought I
> remembered sed having an option to just report what changes it WOULD HAVE
> made without actually making the changes.  But I can't find anything like
> that.
> 
> Best I can think of is to make a test directory [hierarchy], copy your files
> into it, run the sed command and then look at all the files for intended and
> unintended changes (or diff them from the originals).  That would seem to
> suck!
> 
> 
> 
> 
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