term% ls -F
term% cat index.txt
PERROR(2)                     System Calls Manual                    PERROR(2)

       perror, syslog - system error messages

       #include <u.h>
       #include <libc.h>

       void perror(char *s)

       void syslog(int cons, char *logname, char *fmt, ...)

       Perror  produces  a  short error message on the standard error file de‐
       scribing 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 0, only the error message and newline are printed.

       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  ar‐
       guments; 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.


       intro(2), errstr(2), the %r format in print(2)

       Perror is a holdover; the %r format in print(2) is preferred.