Linux shell to restrict sftp users to their home directories?

OpenSSH≥4.8 supports a ChrootDirectory directive.

Add to /etc/sshd_config or /etc/ssh/sshd_config or whatever your setup’s global sshd config file is:

Match user ben_files
        # The following two directives force ben_files to become chrooted
        # and only have sftp available.  No other chroot setup is required.
        ChrootDirectory /var/www/vhosts/mydomain.example/files
        ForceCommand internal-sftp
        # For additional paranoia, disallow all types of port forwardings.
        AllowTcpForwarding no
        GatewayPorts no
        X11Forwarding no