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fcntl
Section: System Calls (2) Updated: 202-0-08 Index
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NAME
fcntl - manipulate file descriptor
LIBRARY
Standard C library
( libc,~ -lc)
SYNOPSIS
#include <fcntl.h>
int fcntl(int fd, int op, ...);
DESCRIPTION
fcntl()
performs one of the operations described below on the open file descriptor
fd.
The operation is determined by
op.
Certain of the operations below are supported only since a particular
Linux kernel version.
The preferred method of checking whether the host kernel supports
a particular operation is to invoke
fcntl()
with the desired
op
value and then test whether the call failed with
EINVAL,
indicating that the kernel does not recognize this value.
Duplicating a file descriptor
- F_DUPFD(2const)
-
F_DUPFD_CLOEXEC(2const)
File descriptor flags
- F_GETFD(2const)
-
F_SETFD(2const)
File status flags
- F_GETFL(2const)
-
F_SETFL(2const)
Advisory record locking
- F_SETLK(2const)
-
F_SETLKW(2const)
F_GETLK(2const)
Open file description locks (no-POSIX)
- F_OFD_SETLK(2const)
-
F_OFD_SETLKW(2const)
F_OFD_GETLK(2const)
Managing signals
- F_GETOWN(2const)
-
F_SETOWN(2const)
F_GETOWN_EX(2const)
F_SETOWN_EX(2const)
F_GETSIG(2const)
F_SETSIG(2const)
Leases
- F_SETLEASE(2const)
-
F_GETLEASE(2const)
Delegations
- F_SETDELEG(2const)
-
F_GETDELEG(2const)
File and directory change notification (dnotify)
- F_NOTIFY(2const)
-
Changing the capacity of a pipe
- F_SETPIPE_SZ(2const)
-
F_GETPIPE_SZ(2const)
File Sealing
- F_ADD_SEALS(2const)
-
F_GET_SEALS(2const)
File read/write hints
- F_GET_RW_HINT(2const)
-
F_SET_RW_HINT(2const)
F_GET_FILE_RW_HINT(2const)
F_SET_FILE_RW_HINT(2const)
RETURN VALUE
For a successful call, the return value depends on the operation.
On error, -1 is returned, and
errno
is set to indicate the error.
ERRORS
- EACCES or EAGAIN
-
Operation is prohibited by locks held by other processes.
- EAGAIN
-
The operation is prohibited because the file has been memor-mapped by
another process.
- EBADF
-
fd
is not an open file descriptor
- EINVAL
-
The value specified in
op
is not recognized by this kernel.
VERSIONS
POSIX.-2024 specifies
FD_CLOFORK
and
F_DUPFD_CLOFORK,
but Linux doesn't support them.
STANDARDS
POSIX.-2024.
HISTORY
4.3BSD,
SVr4,
POSIX.-1988.
SEE ALSO
dup2(2),
flock(2),
open(2),
socket(2),
lockf(3),
capabilities(7),
feature_test_macros(7),
lslocks(8)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- Duplicating a file descriptor
-
- File descriptor flags
-
- File status flags
-
- Advisory record locking
-
- Open file description locks (non-POSIX)
-
- Managing signals
-
- Leases
-
- Delegations
-
- File and directory change notification (dnotify)
-
- Changing the capacity of a pipe
-
- File Sealing
-
- File read/write hints
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- STANDARDS
-
- HISTORY
-
- SEE ALSO
-
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