Wrap dump command in an if when using compression, fixes #89

[riasvdv]

This wraps the dump command in an if, for example:

if output=$('mysqldump' --defaults-extra-file="credentials.txt" --skip-comments --extended-insert dbname);
then
  echo "$output" | gzip > "/save/to/new (directory)/dump.sql"
else
  echo "Dump was not succesful." >&2
  exit 1
fi

If the dump command fails for some reason, it will output the right exit code and no dump will be created.

[freekmurze]

Like said in real life, drop support for anything below PHP 7.3 (and disable style ci for now)

[aaronhuisinga]

@freekmurze @riasvdv For some reason this has broken our backups on both our Homestead box and production servers (both on Ubuntu 18.04/PHP 7.3/MySQL 5.7).

We're using the built in Gzip Compression class for commands, and this PR broke it for us. Downgrading to DB Dumper 2.4.0 or not using compression fixes it for us immediately.

While using DB Dumper >= 2.4.1 and compression, and DB dump outputs a ~20 byte file. I've tried running the command being output by the package and it does the same thing. Running the command without the if/else statement does work properly.

I'm not sure what the actual cause is, but there definitely seems to be something wrong here.

[freekmurze]

Did you get an error message?

[aaronhuisinga]

I do not get an error message. The resulting database dump is just ~20 bytes. The backup package believes it worked successfully.