ispconfig_update.sh script finish with errors

Update finished.

/usr/local/ispconfig/server/scripts/update_from_tgz.sh: line 21: -d: command not found

/usr/local/ispconfig/server/scripts/update_from_tgz.sh: line 26: syntax error near unexpected token `else'

/usr/local/ispconfig/server/scripts/update_from_tgz.sh: line 26: `else'

/usr/local/bin/ispconfig_update.sh: line 4: -d: command not found