# truncate

## 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, _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.
    


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