Use this documentation with care! It describes the outdated version 7, which was actively developed around 2014 and is considered dead by the rsyslog team.

This documentation reflects the latest update of the v7-stable branch. It describes the 7.6.8 version, which was never released. As such, it contains some content that does not apply to any released version.

To obtain the doc that properly matches your installed v7 version, obtain the doc set from your distro. Each version of rsyslog contained the version that exactly matches it.

As general advise, it is strongly suggested to upgrade to the current version supported by the rsyslog project. The current version can always be found on the right-hand side info box on the rsyslog web site.

Note that there is only limited rsyslog community support available for the outdated v7 version (officially we do not support it at all, but we usually are able to answer simple questions). If you need to stick with v7, it probably is best to ask your distribution for support.


RainerScript supports a currently quite limited set of functions:

  • getenv(str) - like the OS call, returns the value of the environment variable, if it exists. Returns an empty string if it does not exist.
  • strlen(str) - returns the length of the provided string
  • tolower(str) - converts the provided string into lowercase
  • cstr(expr) - converts expr to a string value
  • cnum(expr) - converts expr to a number (integer)
  • re_match(expr, re) - returns 1, if expr matches re, 0 otherwise
  • re_extract(expr, re, match, submatch, no-found) - extracts data from a string (property) via a regular expression match. POSIX ERE regular expressions are used. The variable “match” contains the number of the match to use. This permits to pick up more than the first expression match. Submatch is the submatch to match (max 50 supported). The “no-found” parameter specifies which string is to be returned in case when the regular expression is not found. Note that match and submatch start with zero. It currently is not possible to extract more than one submatch with a single call.
  • field(str, delim, matchnbr) - returns a field-based substring. str is the string to search, delim is the delimiter and matchnbr is the match to search for (the first match starts at 1). This works similar as the field based property-replacer option. Versions prior to 7.3.7 only support a single character as delimiter character. Starting with version 7.3.7, a full string can be used as delimiter. If a single character is being used as delimiter, delim is the numerical ascii value of the field delimiter character (so that non-printable characters can by specified). If a string is used as delmiter, a multi-character string (e.g. “#011”) is to be specified. Samples: set $!usr!field = field($msg, 32, 3); – the third field, delimited by space set $!usr!field = field($msg, "#011", 3); – the third field, delmited by “#011” Note that when a single character is specified as string [field($msg, “,”, 3)] a string-based extraction is done, which is more performance intense than the equivalent single-character [field($msg, 44 ,3)] extraction.
  • prifilt(constant) - mimics a traditional PRI-based filter (like “*.*” or “”). The traditional filter string must be given as a constant string. Dynamic string evaluation is not permitted (for performance reasons).

The following example can be used to build a dynamic filter based on some environment variable:

if $msg contains getenv('TRIGGERVAR') then /path/to/errfile

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