PERROR(S) UNIX System V PERROR(S)
Name
perror, errno, sys_errlist, sys_nerr - system error messages
Syntax
void perror (s)
char *s;
extern int errno;
extern char *sys_errlist[ ];
extern int sys_nerr;
Description
The perror function produces a message on the standard error
output, describing the last error encountered during a call
to a system or library function. The argument string s is
printed first, then a colon and a blank, then the message
and a new-line. (However, if s="", the colon is not
printed.) To be of most use, the argument string should
include the name of the program that incurred the error.
The error number is taken from the external variable errno,
which is set when errors occur but not cleared when non-
erroneous calls are made.
To simplify variant formatting of messages, the array of
message strings sys_errlist is provided; errno can be used
as an index into this table to get the message string
without the new-line. sys_nerr is the number of messages in
the table; it should be checked because new error codes may
be added to the system before they are added to the table.
See Also
intro(S)
Standards Conformance
errno is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
perror is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
ANSI X3.159-198X C Language Draft Standard, May 13,
1988;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
sys_errlist and sys_nerr are conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 6/20/89)