.TH PERROR 2.SH NAMEperror, syslog, sysfatal \- system error messages.SH SYNOPSIS.B #include <u.h>.br.B #include <libc.h>.PP.Bvoid perror(char *s).PP.Bvoid syslog(int cons, char *logname, char *fmt, ...).PP.Bvoid sysfatal(char *fmt, ...).SH DESCRIPTION.I Perrorproduces a short error messageon the standard error filedescribing the last error encountered during a callto the system.First the argument string.I sis printed, then a colon, then the message and a newline.If.I sis nil, only the error message and newline are printed..PP.I Sysloglogs messages in the file named by.I lognamein the directory.BR /sys/log ;the file must already exist and should be append-only..I Lognamemust contain no slashes.The message is a line with several fields:the name of the machine writing the message;the date and time;the message specified by the.IR print (2)format.I fmtand any following arguments;and a final newline.If.I consis set or the log file cannot be opened, the message is also printedon the system console..I Syslogcan be used safely in multi-threaded programs..PP.I Sysfatalprints to standard error the name of the running program,a colon and a space, the message described by the.IR print (2)format string.I fmtand subsequent arguments, and a newline.It then calls.IR exits (2)with the formatted message as argument.The program's name is the value of.BR argv0 ,which will be set if the program uses the.IR arg (2)interface to process its arguments.If.B argv0is null, it is ignored and the following colon and space are suppressed..SH SOURCE.B /sys/src/libc/port/perror.c.br.B /sys/src/libc/9sys/syslog.c.br.B /sys/src/libc/9sys/sysfatal.c.SH "SEE ALSO".IR intro (2),.IR errstr (2),the.B %rformat in.IR print (2).SH BUGS.I Perroris a holdover; the.B %rformat in.IR print (2)is preferred.