The manpage says, that -S and -C can be used for read-only media.
However this does not work:

$ mkdir test
$ chmod 500 test
$ syrep -v -Stest.syrep -Ctest.md-cache --update test
mkdir("test/.syrep"): Permission denied
Wrote version 1.
open("test/.syrep/current.syrep"): No such file or directory
$

Why should syrep create test/.syrep?

Actually no test.syrep was written, so the second message is false.

Am I doing it wrong? Support for read-only directories would be nice to
have, but if it doesn't work, at least the manpage should be corrected.

Helmut

Hi,

I forward this bug to the upstream author.

Regards,

Dear submitter,

as the package syrep has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143102

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)