setting ulimit -n with a value more than 1024000

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Top Forums UNIX for Advanced & Expert Users setting ulimit -n with a value more than 1024000
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Old 08-04-2009
Originally Posted by Hsianglung Wu
Thank you for the replies.

Actually I tried ulimit -n unlimited before and I got the same error as using
ulimit -n <value> when value is greater than 1024000

The application indeed is running on a cluster setting. In the extreme scaling situation the application will need to open a huge number of files concurrently. Will it have scaling issue? This is a part of my intention - to find it out.

I have a feeling that it might need kernel recompilation. Any hint which conf file or .h file needs to be changed?

In AIX you can set the hard limit to -1 for an unlimited ulimit in /etc/security/limits. I think in Linux the file is /etc/security/limits.conf. Each user has its own hard limits. There should be examples in the file.
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ULIMIT(3P)						     POSIX Programmer's Manual							ULIMIT(3P)

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
ulimit -- get and set process limits SYNOPSIS
#include <ulimit.h> long ulimit(int cmd, ...); DESCRIPTION
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. RETURN VALUE
Upon successful completion, ulimit() shall return the value of the requested limit. Otherwise, -1 shall be returned and errno set to indi- cate the error. ERRORS
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. The following sections are informative. EXAMPLES
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. RATIONALE
The ulimit() function may be removed in a future version. SEE ALSO
exec, getrlimit(), write() The Base Definitions volume of POSIX.1-2008, <ulimit.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 . 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 . IEEE
/The Open Group 2013 ULIMIT(3P)