There is some strange thing that when I use "zabbix_agentd -t ..." in versions 2.0.0-2.0.4 I'm getting my hostname ("it0") as a value for the key vfs.file.contents
I'm not sure it will work so on other hosts.
On a WindowsXP host with v2.0.3 I'm getting a garbage (not its hostname).

Tests on my Linux host:

# ./2.0.4/zabbix_agentd_2.0.4 -t vfs.file.contents[/tmp/ttt]
vfs.file.contents[/tmp/ttt]                   [t|it0]

# ./2.0.4/zabbix_agentd_2.0.4 -V
Zabbix Agent (daemon) v2.0.4 (revision 32392) (08 December 2012)
Compilation time: Jan 21 2013 14:57:19

# ./zabbix20/zabbix_agentd20 -t vfs.file.contents[/tmp/ttt]
vfs.file.contents[/tmp/ttt][/tmp/ttt]         [t|�ef]

# ./zabbix20/zabbix_agentd20 -V
Zabbix Agent (daemon) v2.0.5rc1 (revision 32959) (08 December 2012)
Compilation time: Jan 21 2013 14:59:44

By zabbix_get:

# zabbix_get -s localhost -p 10060 -k agent.version
2.0.4
# zabbix_get -s localhost -p 10060 -k vfs.file.contents[/tmp/ttt]
��$�(

restarted agent current 2.0 HEAD:

# zabbix_get -s localhost -p 10060 -k agent.version
2.0.5rc1
# zabbix_get -s localhost -p 10060 -k vfs.file.contents[/tmp/ttt]
(�A

The same problem if zabbix doesn't have permissions to a file.

The file reading buffer was not initialized resulting in undefined data when empty file is read. So it could return anything (including garbage data or interface names).

However when trying to access file without read rights a 'not supported' error is always returned.

Fixed in svn://svn.zabbix.com/branches/dev/ZBX-6161

Well, now (dev branch) for the empty file I'm getting a text "EOF"

We use currently this approach for "vfs.file.regexp[file,regexp,<encoding>]" key.

Hmmm, I personally not very sure that it's good to return EOF for "vfs.file.contents", need to get more opinions.

Why we cannot return just empty value "" if file is empty ?
Zabbix server 2.0+ support this for textual items.

And this should be added to doc, here https://www.zabbix.com/documentation/2.0/manual/config/items/itemtypes/zabbix_agent

it must be an empty value otherwise we can't differentiate between an empty file and file with contents "EOF"

zalex_ua and ... the same we can say about "vfs.file.regexp" key, and I'm also not very happy on this.
For the "vfs.file.regexp" we also could return an empty value, as 2.0 supports this. Of course ... backward compatibility ... heh
Maybe we could reconsider this ?

<richlv> agreed. not sure whether we can handle all that in this issue

zalex_ua if we will end up with the empty value instead of EOF for "vfs.file.contents", then we will create separate request for "vfs.file.regexp", addressed I suppose for next major release.

sasha richlv, zalex: It's a different issue. We can't change the behavior inside 2.0. You can open a new ZBXNEXT.

FYI: also "EOF" can return web.page.get and web.page.regexp.

CLOSED

just a sidenote - would be awesome to have some tests for this

Successfully tested!

Fixed in:
pre-2.0.5rc1 r33066
pre-2.1.0 r33067

Heh, we need answers on comments above.
Also - documentation looks like not updated, disregarding on a comment above.

Sorry, REOPENED.

vfs.file.contents originally returned (or tried to) EOF for empty files. Only because of this bug the real empty files returned random garbage, while files containing only LF/CR characters were trimmed to empty contents and EOF was properly returned.

As no features were changed/added I don't see why documentation should be changed (unless it was wrong in the first case).

Regarding the idea itself of empty files returning EOF - I agree that it would be better to return empty string. But that would be a feature change, so I believe it must go as a new request.

I'm closing the issue.

heh, thank you for explanation Andris and Alexander !

In any case this piece of information still has to be added to doc, and I've just did it:
"Contents of a file or EOF if it is empty or it contains only LF/CR characters."
to
https://www.zabbix.com/documentation/2.0/manual/config/items/itemtypes/zabbix_agent
https://www.zabbix.com/documentation/2.2/manual/config/items/itemtypes/zabbix_agent

You could review.

Maybe instead of "Contents of a file or EOF" it would be better to write "Contents of a file or a string 'EOF'" or something. Otherwise some people might think that -1 is returned.

The same is true about vfs.file.regexp description.

The idea to return an empty value instead of EOF moved to ZBX-6171