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Hacking in UNIX
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ulimit(1) General Commands Manual ulimit(1) NAME
ulimit - Sets or reports a resource limit SYNOPSIS
ulimit [-HSacdfmnstvw] [limit] STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: ulimit: XCU5.0, XBD5.0 Refer to the standards(5) reference page for more information about industry standards and associated tags. OPTIONS
[Tru64 UNIX] The limits specified for the resources are hard limits. A hard limit cannot be increased once it is set. [Tru64 UNIX] The limits specified for the resources are soft limits. A soft limit can be increased up to the value of the hard limit. [Tru64 UNIX] Lists all of the current resource limits. The limit operand is not permitted with this option. [Tru64 UNIX] The limit operand specifies the number of 512-byte blocks for core dumps. [Tru64 UNIX] The limit operand specifies the number of Kilobytes for the data area. The limit operand specifies the number of 512-byte blocks for files written by child processes (files of any size can be read). [Tru64 UNIX] The limit operand specifies the number of Kilobytes for the size of physical memory. [Tru64 UNIX] The limit operand specifies the number of file descriptors. [Tru64 UNIX] The limit operand specifies the number of Kilobytes for the stack area. [Tru64 UNIX] The limit op- erand specifies the number of seconds to be used by each process. [Tru64 UNIX] The limit operand specifies the number of Kilobytes for virtual memory. This option is supported only if RLIMIT_VMEM has been defined in /usr/include/sys/resource.h at compile-time. [Tru64 UNIX] The limit operand specifies the number of Kilobytes for the swap area. This option is supported only if RLIMIT_SWAP has been defined in /usr/include/sys/resource.h at compile-time. OPERANDS
If no options are specified, this is the number of 512 byte blocks to use as the new limit to file size. Otherwise, it is the limit applied to the resource indicatd by the option. [Tru64 UNIX] This operand is not allowed with the -a option. If this operand is omitted, the current limit for the indicated resource is reported. DESCRIPTION
This command sets, or reports, the limit on the size of system resources, as indicated by the option. [Tru64 UNIX] If neither the -H option nor the -S option is specified, the limit applies to both hard and soft limits. If only the -a option is specified, soft limits are reported. If there is no limit on a resource, the limit is reported as unlimited. NOTES
The ulimit command affects only the current execution environment, therefore it has no effect when run in a separate execution environment such as one of the following: nohup ulimit -f 10000 env ulimit 10000 RESTRICTIONS
Once a limit has been decreased, only a user with superuser privileges may increase it, even back to its original value. EXIT STATUS
The following exit values are returned: Successful completion. A request for a higher limit was rejected or an error occurred. EXAMPLES
To set the file size limit to 51,200 bytes, enter: ulimit -f 100 To report the current file size limit, enter: ulimit The following example displays all current resource limits: % ulimit -a time(seconds) unlimited file(blocks) unlimited data(kbytes) 131072 stack(kbytes) 2048 memory(kbytes) 84280 coredump(blocks) unlimited nofiles(descriptors) 4096 vmemory(kbytes) 1048576 ENVIRONMENT VARIABLES
The following environment variables affect the execution of ulimit: Provides a default value for the internationalization variables that are unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization variables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value, overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multibyte characters in arguments). Determines the locale for the format and contents of diagnostic messages written to standard error. Determines the location of message catalogues for the processing of LC_MESSAGES. SEE ALSO
Routines: ulimit(3) Standards: standards(5) ulimit(1)
