Recurring csh Shell Bug Prompts Engineers to Build SSH Command Wrapper

In June 2026, database backups began failing on all Sakura Internet-hosted WordPress sites due to an SSH error traced back to a recurring shell compatibility issue. Sakura's default login shell, csh, cannot interpret bash syntax, and a newly added DB backup progress-monitoring feature had bypassed an earlier safeguard that was meant to prevent this exact problem. Developers first attempted a fix using base64 encoding via OpenSSL, but discovered that another hosting environment, heteml, lacked the required OpenSSL command entirely. The final solution was a Python wrapper function using shlex.quote() to pass scripts directly as arguments to /bin/sh -c, eliminating any dependency on external commands. The approach works regardless of the server's login shell, requires only that scripts be single-line, and has since been verified across multiple hosting environments.