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Pawel Veselov
Asked: 2013-01-05 15:22:29 +0800 CST

What does "-/filepath" ACTION mean in rsyslog configuration

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I came across this one Debian Linux installation (6.0.6), and examining its /etc/rsyslog.conf, I see configuration lines like this:

auth,authpriv.*                 /var/log/auth.log
*.*;auth,authpriv.none          -/var/log/syslog

I can't find anything about prepending dashes to the file action in rsyslog.conf(5), and what the meaning of it might be, and would like to know what they actually do.

linux

2 Answers

  1. Best Answer

    Googled this a bit more, and found this.

    In essence, it means to not synchronize the log file to disk every time there is a write, if synchronization behavior is on by default.

    It is stated that since v3 the default behavior is not sync, and it's possible to change this by specifying "$ActionFileEnableSync on/off".

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  2. To add a bit more context, the "Configuration » Actions" documentation page describes the significance of prefixing output filenames with a - (U+002D "HYPHEN-MINUS"):

    You may prefix each entry with the minus “-‘’ sign to omit syncing the file after every logging.

    However, that page does not mention the $ActionFileEnableSync configuration statement, nor that it defaults to off as of v3.12.4 (released on 2008-03-25, according to the ChangeLog).

    EDIT: I originally (mis)read the page @Pawel linked to, missing the relevant remark inside a parenthetical there:

    Rsyslogd tries to keep as compatible to stock syslogd as possible. As such, it retained stock syslogd’s default of syncing every file write if not specified otherwise (by placing a dash in front of the output file name).

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