<p>I'm writing a quick Rails app and was wondering how I can validate the success an exec'd command.  The two commands I'm running are and SVN update, and a cp from one directory to another.</p>

For SVN update, check the version number before and after the update.
```
```
svn_start_version = IO.popen("svn info").readlines[4]
`svn update`
svn_end_version = IO.popen("svn info").readlines[4]
if svn_end_version > svn_start_version
  "success"
end
```
```
For the cp, you could do a filesize check on the original file being equal to the copied file.
```
```
source_file_size = IO.popen("du file1").readlines
`cp file1 file2`
dest_file_size = IO.popen("du file2").readlines
if dest_file_size == source_file_size
  "success"
end
```
```