open.2

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th OPEN II 8/5/73
.sh NAME
open \*- open for reading or writing
.sh SYNOPSIS
(open = 5.)
.br
.ft B
sys open; name; mode
.br
.ft R
(file descriptor in r0)
.s3
.ft B
open(name, mode)
.br
char *name;
.ft R
.sh DESCRIPTION
.it Open
opens the file
.it name
for reading
(if
.it mode
is 0),
writing (if
.it mode
is 1) or for both reading and writing
(if
.it mode
is 2).
.it Name
is the address of a string of ASCII characters representing
a path name, terminated by a null character.
.s3
The returned file descriptor should be saved for subsequent calls
to
.it read,
.it write,
and
.it close.
.sh "SEE ALSO"
creat (II), read (II), write (II), close (II)
.sh DIAGNOSTICS
The error bit
(c-bit) is set if the file does not exist,
if one of the necessary directories
does not exist or is unreadable, if the file is not
readable (resp. writable), or if too many files are open.
From C, a \*-1 value is returned on an error.