posix man page for truncate

TRUNCATE(3P)						     POSIX Programmer's Manual						      TRUNCATE(3P)

PROLOG
       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
       truncate -- truncate a file to a specified length

SYNOPSIS
       #include <unistd.h>

       int truncate(const char *path, off_t length);

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  comple-
       tion,  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.

RETURN VALUE
       Upon successful completion, truncate() shall return 0. Otherwise, -1 shall be returned, and errno set to indicate the error.

ERRORS
       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.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       open()

       The Base Definitions volume of POSIX.1-2008, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
       ogy -- 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 Stan-
       dard 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)