General Logging

Syntax: log size:200k count:5

Log rotation for run/task/services using the log sub-option with redirection to a log file. Global setting, applies to all services.

The size can be given as bytes, without a specifier, or in k, M, or G, e.g. size:10M, or size:3G. A value of size:0 disables log rotation. The default is 200k.

The count value is recommended to be between 1-5, with a default 5. Setting count to 0 means the logfile will be truncated when the MAX size limit is reached.

Redirecting Output

The run, task, and service stanzas also allow the keyword log to redirect stderr and stdout of the application to a file or syslog using the native logit tool. This is useful for programs that do not support syslog on their own, which is sometimes the case when running in the foreground.

The full syntax is:

log:/path/to/file
log:prio:facility.level,tag:ident
log:console
log:null
log

Default prio is daemon.info and default tag is the basename of the service or run/task command.

Log rotation is controlled using the global log setting.

Example:

service log:prio:user.warn,tag:ntpd /sbin/ntpd pool.ntp.org -- NTP daemon

Output Buffering

When using the log directive, Finit redirects the service's stdout and stderr to a pipe connected to a logger process. Programs detect this as non-interactive output (i.e., isatty() returns false) and typically switch from line-buffered to fully-buffered mode.

Most well-behaved daemons explicitly flush their output or use syslog directly, so this is rarely an issue. However, if a service's log messages appear delayed or batched, you can force line-buffered output by wrapping the command with stdbuf:

service log /usr/bin/stdbuf -oL /path/to/command -- My service

The -oL option forces line-buffered output, and -o0 forces unbuffered output. See stdbuf(1) for details.

Note

Using stdbuf is rarely necessary. Only use it if you observe actual buffering issues with a specific service.