I run devtest_linux_x64.sh on Redhat Enterprise and this error is invoked;
gzip: sfx_archive.tar.gz: not in gzip format
I am sorry, but the installer file seems to be corrupted.
If you downloaded that file please try it again. If you
transfer that file with ftp please make sure that you are
using binary mode.
All supported DevTest environments
This message is generated when the file has been transferred in text mode as opposed to binary.
You will need to FTP the devtest_linux_x64.sh file as binary to your Linux machine. Altering the file transfer settings resolved this issue.