irssi/docs/help/in/log.in

@SYNTAX:log@

     -noopen: Create the entry to log list, but don't start logging
     -autoopen: Automatically open this log file at startup
     -<server tag>: Targets are logged only in this server
     -targets: Log only in specified channels/nicks (space separated list)
     -window: Log output in the window. Active window is used by default, or
              you can give the window's refnum in -targets.
     <filename>: File name where to log, it is parsed with
                 strftime(), so %%d=day, etc. see "man strftime" for
                 more info.
     <levels>: Defaults to ALL
     <id>: ID number of log.   

/SET log_create_mode <mode> - Specifies what file mode to use with
     the created log files. Default is 0600.

All of these are parsed with strftime():
/SET log_timestamp <text> - Specifies the time stamp format.
     Default is "%%H:%%M ".
/SET log_open_string <text> - Text written to log when it's opened
/SET log_close_string <text> - Text written to log when it's closed
/SET log_day_changed <text> - Text written to log when day changes

NOTE: Log files are locked after opened, so two Irssis can't
accidentally try to write to the same log file.

Examples:
        
/LOG OPEN -targets cras ~/irclogs/cras.log MSGS
     - Logs all messages from/to nick `cras'

/LOG OPEN -targets #linux ~/irclogs/linux/linux-%%Y-%%m-%%d
     - Logs all messages in channel #linux. Log is rotated daily, so
       logs in 1. May 2000 goes to file "linux-2000-05-01", when the
       day is changed, Irssi closes the log and starts logging to
       "linux-2000-05-02" etc.

See also: SET LOG, WINDOW LOG