ref: 58668339bcdf71112b08ccc120609dbf7be478dd
dir: /sys/man/2/perror/
.TH PERROR 2 .SH NAME perror, syslog, sysfatal \- system error messages .SH SYNOPSIS .B #include <u.h> .br .B #include <libc.h> .PP .B void perror(char *s) .PP .B void syslog(int cons, char *logname, char *fmt, ...) .PP .B void sysfatal(char *fmt, ...) .SH DESCRIPTION .I Perror produces a short error message on the standard error file describing the last error encountered during a call to the system. First the argument string .I s is printed, then a colon, then the message and a newline. If .I s is nil, only the error message and newline are printed. .PP .I Syslog logs messages in the file named by .I logname in the directory .BR /sys/log ; the file must already exist and should be append-only. .I Logname must 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 fmt and any following arguments; and a final newline. If .I cons is set or the log file cannot be opened, the message is also printed on the system console. .I Syslog can be used safely in multi-threaded programs. .PP .I Sysfatal prints 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 fmt and 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 argv0 is 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 %r format in .IR print (2) .SH BUGS .I Perror is a holdover; the .B %r format in .IR print (2) is preferred.