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TRUNCATE(3P) POSIX Programmer's Manual TRUNCATE(3P)
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.
truncate — truncate a file to a specified length
#include <unistd.h>
int truncate(const char *path, off_t length);
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, if the file size is changed, 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.
Upon successful completion, truncate() shall return 0. Otherwise, −1
shall be returned, and errno set to indicate the 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.
None.
None.
None.
None.
open(3p)
The Base Definitions volume of POSIX.1‐2008, unistd.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 TRUNCATE(3P)
Pages that refer to this page: unistd.h(0p), ftruncate(3p)