This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       Since  the  ulimit() function uses type long rather than rlim_t, this function is not sufficient for file
       sizes on many current systems.  Applications should use the getrlimit() or setrlimit() functions  instead
       of the obsolescent ulimit() function.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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                                   2017                                        ULIMIT(3POSIX)

       The  ulimit()  function  shall  control process limits. The process limits that can be controlled by this
       function include the maximum size of a single file that can be  written  (this  is  equivalent  to  using
       setrlimit() with RLIMIT_FSIZE). The cmd values, defined in <ulimit.h>, include:

       UL_GETFSIZE Return  the  file  size  limit  (RLIMIT_FSIZE) of the process. The limit shall be in units of
                   512-byte blocks and shall be inherited by child processes. Files of any size can be read. The
                   return value shall be the integer part of the soft file size limit divided  by  512.  If  the
                   result cannot be represented as a long, the result is unspecified.

       UL_SETFSIZE Set  the  file  size  limit  for  output operations of the process to the value of the second
                   argument, taken as a long, multiplied by 512. If the result would  overflow  an  rlim_t,  the
                   actual  value  set is unspecified. Any process may decrease its own limit, but only a process
                   with appropriate privileges may increase the limit. The return value  shall  be  the  integer
                   part of the new file size limit divided by 512.

       The ulimit() function shall not change the setting of errno if successful.

       As all return values are permissible in a successful situation, an application wishing to check for error
       situations  should  set  errno  to 0, then call ulimit(), and, if it returns -1, check to see if errno is
       non-zero.

       The ulimit() function shall fail and the limit shall be unchanged if:

       EINVAL The cmd argument is not valid.

       EPERM  A process not having appropriate privileges attempts to increase its file size limit.

       Thefollowingsectionsareinformative.

       None.

       The ulimit() function may be removed in a future version.

       ulimit — get and set process limits

       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.

       None.

       Upon successful completion, ulimit() shall return the value of the requested limit. Otherwise,  -1  shall
       be returned and errno set to indicate the error.

exec, getrlimit(), write()

       The Base Definitions volume of POSIX.1‐2017, <ulimit.h>

       #include <ulimit.h>

       long ulimit(int cmd, ...);