IOError - cannot create file (linux daemon-invoked script)

[cassiope]

On Jan 2, 8:02 pm, Cameron Simpson <c... at zip.com.au> wrote:
> On 02Jan2010 15:21, cassiope <f... at u.washington.edu> wrote:
> | [...]  I want
> | to save a copy of the email in a particular directory which is
> | accessible to the Windows clients via samba.
> |
> | The strange thing is that even with the right user-id, I cannot seem
> | to write to the directory, getting an IOError exception.  Changing the
> | directory to world-writable fixes this.  I can confirm the uid and gid
> | for the script by having the script print these values just before
> | trying to create/write the file.  Becoming the same lesser user, I
> | have no problem writing a file to the same directory.
>
> Can you show us:
>   - the directory user and group ownership and permissions
>   - the daemon's user and group values?

Directory permissions: 774
Directory ownership: "lesser user", "special group" where /etc/group
has
   "special group" members including the "lesser user", as well as
those
   who are expected to use the daemon, but not root.
Script ownership: "lesser user"; permissions 755
Daemon ownership: root; permissions: 755 (always started by root).

The script also has to connect to a postgresql database for part of
its
work - that part works,
> You can also strace your daemon:
>
>   strace -f -e trace=file your-daemon your-daemon-args... 2>strace.out
>
> and then examine the log for the precise UNIX-level failure.
>
> Cheers,
> --
> Cameron Simpson <c... at zip.com.au> DoD#743http://www.cskk.ezoshosting.com/cs/
>
> Money won't buy happiness, but it will pay the salary of a large research
> staff to study the problem. - Bill Vaughan

Thanks, Cameron (and Steve and Christian).  My first shot with strace
(it's
been awhile since I've used that - I think your syntax may be a tiny
bit off
- but it's probably the tool I need to use.  Will explore further...