148351Scael.\" Copyright (c) 1980, 1991 Regents of the University of California. 248351Scael.\" All rights reserved. 320436Smckusick.\" 450314Sbostic.\" This code is derived from software contributed to Berkeley by 550314Sbostic.\" the American National Standards Committee X3, on Information 650314Sbostic.\" Processing Systems. 750314Sbostic.\" 848351Scael.\" %sccs.include.redist.man% 920436Smckusick.\" 10*58376Sbostic.\" @(#)strerror.3 6.11 (Berkeley) 03/02/93 1148351Scael.\" 1248351Scael.Dd 1348351Scael.Dt STRERROR 3 1448351Scael.Os BSD 4 1548351Scael.Sh NAME 1648351Scael.Nm perror , 1748351Scael.Nm strerror , 1848351Scael.Nm sys_errlist , 1948351Scael.Nm sys_nerr 2048351Scael.Nd system error messages 2148351Scael.Sh SYNOPSIS 2256414Sbostic.Fd #include <stdio.h> 2348351Scael.Ft void 2448351Scael.Fn perror "const char *string" 25*58376Sbostic.Vt extern char *sys_errlist[]; 26*58376Sbostic.Vt extern int sys_nerr; 2756414Sbostic.Fd #include <string.h> 2848351Scael.Ft char * 2948351Scael.Fn strerror "int errnum" 3048351Scael.Sh DESCRIPTION 3148351ScaelThe 3248351Scael.Fn strerror 3348351Scaeland 3448351Scael.Fn perror 35*58376Sbosticfunctions look up the error message string corresponding to an 3648351Scaelerror number. 3748351Scael.Pp 3848351ScaelThe 39*58376Sbostic.Fn strerror 4048351Scaelfunction accepts an error number argument 4148351Scael.Fa errnum 4248351Scaeland 4348351Scaelreturns a pointer to the corresponding 4448351Scaelmessage string. 4548351Scael.Pp 4648351ScaelThe 4748351Scael.Fn perror 4848351Scaelfunction finds the error message corresponding to the current 4948351Scaelvalue of the global variable 5048351Scael.Va errno 51*58376Sbostic.Pq Xr intro 2 52*58376Sbosticand writes it, followed by a newline, to the 53*58376Sbosticstandard error file descriptor. 5448351ScaelIf the argument 5548351Scael.Fa string 5648351Scaelis 57*58376Sbostic.Pf non- Dv NULL , 58*58376Sbosticit is prepended to the message 5948351Scaelstring and separated from it by 6048351Scaela colon and space 6148351Scael.Pq Ql \&:\ \& . 6248351ScaelIf 6348351Scael.Fa string 6448351Scaelis 65*58376Sbostic.Dv NULL , 6648351Scaelonly the error message string is printed. 6748351Scael.Pp 68*58376SbosticIf 69*58376Sbostic.Fa errnum 70*58376Sbosticis not a recognized error number, 71*58376Sbosticthe error message string will contain 72*58376Sbostic.Dq Li "Unknown error:\0 73*58376Sbosticfollowed by the error number in decimal. 74*58376Sbostic.Pp 7536225SbosticThe message strings can be accessed directly using the external 76*58376Sbosticarray 7748351Scael.Fa sys_errlist . 7848351ScaelThe external value 7948351Scael.Fa sys_nerr 8048351Scaelcontains a count of the messages in 8148351Scael.Fa sys_errlist . 8247016SbosticThe use of these variables is deprecated; 8348351Scael.Fn strerror 8436225Sbosticshould be used instead. 8548351Scael.Sh SEE ALSO 8648351Scael.Xr intro 2 , 8748351Scael.Xr psignal 3 8848351Scael.Sh HISTORY 8948351ScaelThe 9048351Scael.Fn strerror 9148351Scaeland 9248351Scael.Fn perror 9348351Scaelfunctions are 9448351Scael.Ud . 95*58376Sbostic.Sh BUGS 96*58376SbosticFor unknown error numbers, the 97*58376Sbostic.Fn strerror 98*58376Sbosticfunction will return its result in a static buffer which 99*58376Sbosticmay be overwritten by subsequent calls. 100