truncate(2)                  DG/UX 5.4 Rel. 2.01                 truncate(2)


NAME
       truncate - truncate a file to a specified length

SYNOPSIS
       #include <unistd.h>

       int  truncate (path, length)
       char * path;
       long length;

   where:
       path      Address of a pathname

       length    Maximum length of file after truncation

DESCRIPTION
       Truncate causes the file named by path to be truncated to at most
       length bytes in size.  If path refers to a symbolic link, the target
       of the symbolic link is truncated.

       The subject file must reside on a file system device mounted read-
       write.  Also, it must not be a directory.  If mandatory locking is
       enabled on the file, truncate waits until all locks on the file are
       cleared.

       If an error occurs, no changes occur.  Otherwise, the subject file is
       changed with the following consequences:

       ⊕      For files of type `ordinary-disk-file', if the file's size is
              greater than length bytes, it is truncated to that length, and
              the file's size is updated.  If the file's size is less than
              length bytes, the file is lengthened by appending null bytes
              and the file's size is updated.

       ⊕      If file is not of type `ordinary-disk-file', neither its
              contents nor its size are altered.

       ⊕      The `time-last-modified' and `time-last-changed' attributes
              are set to the current time.  These attributes are changed
              even if there is no change to the file's contents.

ACCESS CONTROL
       The calling process must have permission to resolve path.

       The calling process must have write access to the file.

RETURN VALUE
       0      The file was successfully truncated.

       -1     An error occurred. errno is set to indicate the error.

DIAGNOSTICS
       Errno may be set to one of the following error codes:




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truncate(2)                  DG/UX 5.4 Rel. 2.01                 truncate(2)


       EACCES         Write permission is denied for the named file.

       EISDIR         The named file is a directory.

       EROFS          The named file resides on a file system device mounted
                      read-only.

       ENOENT         The file the pathname resolved to does not exist.

       ENOENT         A non-terminal component of the pathname does not
                      exist.

       ENOTDIR        A non-terminal component of the pathname was not a
                      directory or symbolic link.

       ENAMETOOLONG   The pathname exceeds the length limit for pathnames.

       ENAMETOOLONG   A component of the pathname exceeds the length limit
                      for filenames.

       ENOMEM         There are not enough system resources to resolve the
                      pathname or to expand a symbolic link.

       ELOOP          The number of symbolic links encountered during
                      pathname resolution exceeded MAXSYMLINKS.  A symbolic
                      link cycle is suspected.

       EPERM          The pathname contains a character not in the allowed
                      character set.

       EFAULT         The pathname does not completely reside in the
                      process's address space or the pathname does not
                      terminate in the process's address space.

       EINTR          The truncate system call was interrupted while waiting
                      for a mandatory record lock to clear.

SEE ALSO
       creat(2), open(2), ftruncate(3C).

STANDARDS
       When using m88kbcs as the Software Development Environment target,
       the truncate function will be emulated using BCS system calls.  Since
       this emulation uses the open system call,  a failure will occur if
       all file descriptors are in use.  In this case, errno will be set to
       EMFILE.  Also, since this is an emulation requiring several BCS
       system calls, a slight performance degradation may be noticed in
       comparison to using truncate in /lib/libc.a.









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