Differences between current version and revision by previous author of dup(2).
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| Newer page: | version 3 | Last edited on Thursday, October 31, 2002 5:53:01 pm | by PerryLorier | |
| Older page: | version 1 | Last edited on Tuesday, June 4, 2002 12:23:40 am | by perry | Revert |
@@ -1,89 +1,36 @@
-DUP
-!!!DUP
-NAME
-SYNOPSIS
-DESCRIPTION
-RETURN VALUE
-ERRORS
-WARNING
-CONFORMING TO
-SEE ALSO
-----
!!NAME
-
dup, dup2 - duplicate a file descriptor
!!SYNOPSIS
-__#include
-''oldfd''
__);
-dup2
(int__ ''oldfd''__, int__ ''newfd
''__);
-
+
__#include <unistd.h>
__
+
__int dup
(int__ ''oldfd''__);__
+
!!DESCRIPTION
+__dup__ create a copy of the file descriptor ''oldfd''.
-__dup__ and __dup2__ create a copy of the file
-descriptor ''oldfd''.
+After successful return of __dup__, the old and new descriptors may be used interchangeably. They share locks, file position pointers and flags; for example, if the file position is modified by using lseek(2) on one of the descriptors, the position is also changed for the other.
-After successful return of
__dup
__ or __dup2__, the
-old and new descriptors may be used interchangeably. They
-locks, file position pointers and flags; for example,
-if
the file position is modified by using __lseek__
on
-one of the descriptors
, the position is also changed for the
-other
.
+The two descriptors do
__not
__ share the close-
on-exec flag
, however
.
+dup(2) uses the lowest-numbered unused descriptor for the new descriptor.
-The two descriptors do not share the close-on-exec flag,
-however.
-
-
-__dup__ uses the lowest-numbered unused descriptor for
-the new descriptor.
-
-
-__dup2__ makes ''newfd'' be the copy of ''oldfd'',
-closing ''newfd'' first if necessary.
!!RETURN VALUE
+__dup__ returns the new descriptor, or -1 if an error occurred (in which case, ''errno'' is set appropriately).
-__dup__ and __dup2__ return the new descriptor, or -1
-if an error occurred (in which case, ''errno'' is set
-appropriately).
!!ERRORS
+;[EBADF]: ''oldfd'' isn't an open file descriptor
+;[EMFILE]: The process already has the maximum number of file descriptors open and tried to open a new one.
-__EBADF__
-
-
-''oldfd'' isn't an open file descriptor, or ''newfd''
-is out of the allowed range for file
-descriptors.
-
-
-__EMFILE__
-
-
-The process already has the maximum number of file
-descriptors open and tried to open a new one.
-!!WARNING
-
-
-The error returned by __dup2__ is different to that
-returned by __fcntl(__..., __F_DUPFD__, ...__)__
-when ''newfd'' is out of range. On some systems
-__dup2__ also sometimes returns __EINVAL__ like
-__F_DUPFD__.
!!CONFORMING TO
+SVr4, SVID, POSIX, X/OPEN, BSD 4.3. SVr4 documents additional [EINTR] and [ENOLINK] error conditions. POSIX.1 adds [EINTR].
-SVr4, SVID, POSIX, X/OPEN, BSD 4.3. SVr4 documents
-additional EINTR and ENOLINK error conditions. POSIX.1 adds
-EINTR.
!!SEE ALSO
-
-
-
-----
+fcntl(2), open(2), close(2)
