Text edit off-the-wall question

[MikeLieberman]

Is there a command I can issue to test for a value/condition in a text file and if the condition is met to alter the text.

Here's an example. Scattered in 500+ files there are places where the phrase:
So,
is not followed by a [space] but some other character. However there are also places in those files where there is:
So,[space]

I need to test for the condition were [space] does not follow the comma and add a space in all those files holding an aggregate more that 50 megabytes of text.

Can this be done?

[xenopeek]

Sure, with sed. With below command it does the following:
- find a comma that is not followed by a space
- insert a comma after that space and before the character following it

The basic command to test this is as follows (it won't make changes to the file yet):
sed -r 's/,([^[:space:]])/, \1/g' filename
Replace filename with the name of the file to test with in the current directory (you can use Tab key on the terminal to auto-complete partially typed filenames).

Or to save the output in another file so you can study the results:
sed -r 's/,([^[:space:]])/, \1/g' filename > newfilename

If you've confirmed it indeed does what you need you can add the -i option to make it actually write the changes to the file:
sed -r -i 's/,([^[:space:]])/, \1/g' filename

Sed can work on multiple files so you can replace filename in above with * to process all the files in the current directory for example. Or *.txt for all files with .txt extension. If you need more help share some more detail as to how you've organized the files.

[MikeLieberman]

Thanks!