PATHCONF(2) | System Calls Manual | PATHCONF(2) |
pathconf
,
lpathconf
, fpathconf
— get configurable pathname variables
Standard C Library (libc, -lc)
#include
<unistd.h>
long
pathconf
(const
char *path, int
name);
long
lpathconf
(const
char *path, int
name);
long
fpathconf
(int
fd, int name);
The
pathconf
(),
lpathconf
() and fpathconf
()
system calls provide a method for applications to determine the current
value of a configurable system limit or option variable associated with a
pathname or file descriptor.
For
pathconf
()
and lpathconf
(), the path
argument is the name of a file or directory. For
fpathconf
(), the fd argument
is an open file descriptor. The name argument
specifies the system variable to be queried. Symbolic constants for each
name value are found in the include file
<unistd.h>
.
The
lpathconf
()
system call is like pathconf
() except in the case
where the named file is a symbolic link, in which case
lpathconf
() returns information about the link,
while pathconf
() returns information about the file
the link references.
The available values are as follows:
_PC_LINK_MAX
_PC_MAX_CANON
_PC_MAX_INPUT
_PC_NAME_MAX
_PC_PATH_MAX
_PC_PIPE_BUF
_PC_CHOWN_RESTRICTED
_PC_NO_TRUNC
NAME_MAX
} will result in an
[ENAMETOOLONG
] error; otherwise, such components
will be truncated to {NAME_MAX
}.
IEEE Std 1003.1-2001 (“POSIX.1”)
requires the error in all cases, but this behavior was optional in prior
editions of the standard, and some
non-POSIX-compliant file systems do not support
this behavior._PC_VDISABLE
_PC_ASYNC_IO
_PC_PRIO_IO
_PC_SYNC_IO
_PC_ALLOC_SIZE_MIN
_PC_FILESIZEBITS
_PC_REC_INCR_XFER_SIZE
_PC_REC_MIN_XFER_SIZE
and
_PC_REC_MAX_XFER_SIZE
._PC_REC_MAX_XFER_SIZE
_PC_REC_MIN_XFER_SIZE
_PC_REC_XFER_ALIGN
_PC_SYMLINK_MAX
_PC_ACL_EXTENDED
_PC_ACL_NFS4
_PC_ACL_PATH_MAX
_PC_CAP_PRESENT
_PC_INF_PRESENT
_PC_MAC_PRESENT
_PC_MIN_HOLE_SIZE
pathconf
()
and
fpathconf
()
return a positive number that represents the minimum hole size returned in
bytes. The offsets of holes returned will be aligned to this same value. A
special value of 1 is returned if the file system does not specify the
minimum hole size but still reports holes.If the call to pathconf
() or
fpathconf
() is not successful, -1 is returned and
errno is set appropriately. Otherwise, if the variable
is associated with functionality that does not have a limit in the system,
-1 is returned and errno is not modified. Otherwise,
the current variable value is returned.
If any of the following conditions occur, the
pathconf
() and fpathconf
()
system calls shall return -1 and set errno to the
corresponding value.
EINVAL
]EINVAL
]The pathconf
() system call will fail
if:
ENOTDIR
]ENAMETOOLONG
]NAME_MAX
}
characters (but see _PC_NO_TRUNC
above), or an
entire path name exceeded {PATH_MAX
}
characters.ENOENT
]EACCES
]ELOOP
]EIO
]The fpathconf
() system call will fail
if:
The pathconf
() and
fpathconf
() system calls first appeared in
4.4BSD. The lpathconf
()
system call first appeared in FreeBSD 8.0.
July 7, 2009 | Debian |