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.

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 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.

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 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(3POSIX)