TRUNCATE(2) | System Calls Manual | TRUNCATE(2) |
truncate
,
ftruncate
— truncate or
extend a file to a specified length
#include
<unistd.h>
int
truncate
(const
char *path, off_t
length);
int
ftruncate
(int
fd, off_t
length);
truncate
()
causes the file named by path or referenced by
fd to be truncated or extended to
length bytes in size. If the file was larger than this
size, the extra data is lost. If the file was smaller than this size, it
will be extended as if by writing bytes with the value zero. With
ftruncate
(),
the file must be open for writing.
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
truncate
() and
ftruncate
() will fail if:
EINVAL
]EFBIG
]EIO
]In addition, truncate
() may return the
following errors:
ENOTDIR
]ENAMETOOLONG
]NAME_MAX
characters, or an entire pathname (including the terminating NUL) exceeded
PATH_MAX
bytes.ENOENT
]EACCES
]EACCES
]ELOOP
]EISDIR
]EROFS
]ETXTBSY
]EFAULT
]ftruncate
() may return the following
errors:
The truncate
() and
ftruncate
() functions conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
The truncate
() and
ftruncate
() system calls first appeared in
4.1cBSD.
These calls should be generalized to allow ranges of bytes in a file to be discarded.
Use of truncate
() to extend a file is not
portable.
February 11, 2020 | OpenBSD-7.0 |