[unix-history] / man / man3 / perror.3

.th PERROR III 11/5/73
.sh NAME
perror \*- system error messages
.sh SYNOPSIS
.ft B
perror(s)
.br
char *s;
.s3
int sys\*_nerr;
.br
char *sys\*_errlist[];
.s3
int errno;
.ft R
.br
.sh DESCRIPTION
.it Perror
produces a short error message
describing the last error encountered during a call
to the system from a C program.
First the argument string
.it s
is printed, then a colon, then the message and a new-line.
Most usefully, the argument string is the name
of the program which incurred the error.
The error number is taken from the external variable
.it errno,
which is set when errors occur but not cleared when
non-erroneous calls are made.
.s3
To simplify variant formatting
of messages, the vector of message strings
.it sys\*_errlist
is provided;
.it errno
can be used as an index in this table to get the
message string without the newline.
.it Sys\*_nerr
is the largest message number provided for in the table;
it should be checked because new
error codes may be added to the system before
they are added to the table.
.sh "SEE ALSO"
Introduction to System Calls
.sh BUGS
Commit	Line	Data
d834b095 KT	1	.th PERROR III 11/5/73
	2	.sh NAME
	3	perror \*- system error messages
	4	.sh SYNOPSIS
	5	.ft B
	6	perror(s)
	7	.br
	8	char *s;
	9	.s3
	10	int sys\*_nerr;
	11	.br
	12	char sys\_errlist[];
	13	.s3
	14	int errno;
	15	.ft R
	16	.br
	17	.sh DESCRIPTION
	18	.it Perror
	19	produces a short error message
	20	describing the last error encountered during a call
	21	to the system from a C program.
	22	First the argument string
	23	.it s
	24	is printed, then a colon, then the message and a new-line.
	25	Most usefully, the argument string is the name
	26	of the program which incurred the error.
	27	The error number is taken from the external variable
	28	.it errno,
	29	which is set when errors occur but not cleared when
	30	non-erroneous calls are made.
	31	.s3
	32	To simplify variant formatting
	33	of messages, the vector of message strings
	34	.it sys\*_errlist
	35	is provided;
	36	.it errno
	37	can be used as an index in this table to get the
	38	message string without the newline.
	39	.it Sys\*_nerr
	40	is the largest message number provided for in the table;
	41	it should be checked because new
	42	error codes may be added to the system before
	43	they are added to the table.
	44	.sh "SEE ALSO"
	45	Introduction to System Calls
	46	.sh BUGS