обрезать файл до указанной длины (truncate a file to a specified length)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
truncate — truncate a file to a specified length
Синопсис (Synopsis)
#include <unistd.h>
int truncate(const char *path, off_t length);
Описание (Description)
The truncate() function shall cause the regular file named by
path to have a size which shall be equal to length bytes.
If the file previously was larger than length, the extra data is
discarded. If the file was previously shorter than length, its
size is increased, and the extended area appears as if it were
zero-filled.
The application shall ensure that the process has write
permission for the file.
If the request would cause the file size to exceed the soft file
size limit for the process, the request shall fail and the
implementation shall generate the SIGXFSZ signal for the process.
The truncate() function shall not modify the file offset for any
open file descriptions associated with the file. Upon successful
completion, truncate() shall mark for update the last data
modification and last file status change timestamps of the file,
and the S_ISUID and S_ISGID bits of the file mode may be cleared.
Возвращаемое значение (Return value)
Upon successful completion, truncate() shall return 0. Otherwise,
-1 shall be returned, and errno set to indicate the error.
Ошибки (Error)
The truncate() function shall fail if:
EINTR A signal was caught during execution.
EINVAL The length argument was less than 0.
EFBIG or EINVAL
The length argument was greater than the maximum file
size.
EIO An I/O error occurred while reading from or writing to a
file system.
EACCES A component of the path prefix denies search permission,
or write permission is denied on the file.
EISDIR The named file is a directory.
ELOOP A loop exists in symbolic links encountered during
resolution of the path argument.
ENAMETOOLONG
The length of a component of a pathname is longer than
{NAME_MAX}.
ENOENT A component of path does not name an existing file or path
is an empty string.
ENOTDIR
A component of the path prefix names an existing file that
is neither a directory nor a symbolic link to a directory,
or the path argument contains at least one non-<slash>
character and ends with one or more trailing <slash>
characters and the last pathname component names an
existing file that is neither a directory nor a symbolic
link to a directory.
EROFS The named file resides on a read-only file system.
The truncate() function may fail if:
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered
during resolution of the path argument.
ENAMETOOLONG
The length of a pathname exceeds {PATH_MAX}, or pathname
resolution of a symbolic link produced an intermediate
result with a length that exceeds {PATH_MAX}.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
open(3p)
The Base Definitions volume of POSIX.1‐2017, unistd.h(0p)
