term% cat index.txt
PERROR(2) System Calls Manual PERROR(2)
perror, syslog, sysfatal - system error messages
void perror(char *s)
void syslog(int cons, char *logname, char *fmt, ...)
void sysfatal(char *fmt, ...)
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 s is printed, then a colon, then the message
and a newline. If s is nil, only the error message and newline are
Syslog logs messages in the file named by logname in the directory
/sys/log; the file must already exist and should be append-only. Log‐
name 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 print(2) format fmt and any following
arguments; and a final newline. If cons is set or the log file cannot
be opened, the message is also printed on the system console. Syslog
can be used safely in multi-threaded programs.
Sysfatal prints to standard error the name of the running program, a
colon and a space, the message described by the print(2) format string
fmt and subsequent arguments, and a newline. It then calls exits(2)
with the formatted message as argument. The program's name is the
value of argv0, which will be set if the program uses the arg(2) inter‐
face to process its arguments. If argv0 is null, it is ignored and the
following colon and space are suppressed.
intro(2), errstr(2), the %r format in print(2)
Perror is a holdover; the %r format in print(2) is preferred.