[unix-history] / usr / man / man3 / fopen.3s

.TH FOPEN 3S 
.SH NAME
fopen, freopen, fdopen \- open a stream
.SH SYNOPSIS
.B #include <stdio.h>
.PP
.SM
.B FILE
.B *fopen(filename, type)
.br
.B char *filename, *type;
.PP
.SM
.B FILE
.B *freopen(filename, type, stream)
.br
.B char *filename, *type;
.br
.SM
.B FILE
.B *stream;
.PP
.SM
.B FILE
.B *fdopen(fildes, type)
.br
.B char *type;
.SH DESCRIPTION
.I Fopen
opens the file named by
.I filename
and associates a stream with it.
.I Fopen
returns a pointer to be used to identify
the stream in subsequent operations.
.PP
.I Type
is a character string having one of the following values:
.TP 5
"r"
open for reading
.ns
.TP 5
"w"
create for writing
.ns
.TP 5
"a"
append: open for writing at end
of file, or create for writing
.PP
.I Freopen
substitutes the named file in place
of the open
.IR stream .
It returns the original value of
.IR stream .
The original stream is closed.
.PP
.I Freopen
is typically used to attach the preopened
constant names,
.B stdin, stdout, stderr,
to specified files.
.PP
.I Fdopen
associates a stream with a file descriptor obtained from
.I open, dup, creat,
or
.IR pipe (2).
The
.I type
of the stream must agree with the mode of the open file.
.SH "SEE ALSO"
open(2),
fclose(3)
.SH DIAGNOSTICS
.I Fopen
and 
.I freopen
return the pointer
.SM
.B NULL
if
.I filename
cannot be accessed.
.SH BUGS
.I Fdopen
is not portable to systems other than UNIX.
Commit	Line	Data
c4665c80 TL	1	.TH FOPEN 3S
	2	.SH NAME
	3	fopen, freopen, fdopen \- open a stream
	4	.SH SYNOPSIS
	5	.B #include <stdio.h>
	6	.PP
	7	.SM
	8	.B FILE
	9	.B *fopen(filename, type)
	10	.br
	11	.B char filename, type;
	12	.PP
	13	.SM
	14	.B FILE
	15	.B *freopen(filename, type, stream)
	16	.br
	17	.B char filename, type;
	18	.br
	19	.SM
	20	.B FILE
	21	.B *stream;
	22	.PP
	23	.SM
	24	.B FILE
	25	.B *fdopen(fildes, type)
	26	.br
	27	.B char *type;
	28	.SH DESCRIPTION
	29	.I Fopen
	30	opens the file named by
	31	.I filename
	32	and associates a stream with it.
	33	.I Fopen
	34	returns a pointer to be used to identify
	35	the stream in subsequent operations.
	36	.PP
	37	.I Type
	38	is a character string having one of the following values:
	39	.TP 5
	40	"r"
	41	open for reading
	42	.ns
	43	.TP 5
	44	"w"
	45	create for writing
	46	.ns
	47	.TP 5
	48	"a"
	49	append: open for writing at end
	50	of file, or create for writing
	51	.PP
	52	.I Freopen
	53	substitutes the named file in place
	54	of the open
	55	.IR stream .
	56	It returns the original value of
	57	.IR stream .
	58	The original stream is closed.
	59	.PP
	60	.I Freopen
	61	is typically used to attach the preopened
	62	constant names,
	63	.B stdin, stdout, stderr,
	64	to specified files.
65	.PP
66	.I Fdopen
67	associates a stream with a file descriptor obtained from
68	.I open, dup, creat,
69	or
70	.IR pipe (2).
71	The
72	.I type
73	of the stream must agree with the mode of the open file.
74	.SH "SEE ALSO"
75	open(2),
76	fclose(3)
77	.SH DIAGNOSTICS
78	.I Fopen
79	and
80	.I freopen
81	return the pointer
82	.SM
83	.B NULL
84	if
85	.I filename
86	cannot be accessed.
87	.SH BUGS
88	.I Fdopen
89	is not portable to systems other than UNIX.