ulimit - set or report file size limit
The ulimit utility sets or reports the file-size writing limit imposed on files written by the shell and its child processes (files of any size may be read). Only a process with appropriate privileges can increase the limit.
The ulimit utility supports the XBD specification, Utility Syntax Guidelines .
The following option is supported:
- Set (or report, if no blocks operand is present), the file size limit in blocks. The -f option is also the default case.
The following operand is supported:
- The number of 512-byte blocks to use as the new file size limit.
The following environment variables affect the execution of ulimit:
- Provide a default value for the internationalisation variables that are unset or null. If LANG is unset or null, the corresponding value from the implementation-dependent default locale will be used. If any of the internationalisation variables contains an invalid setting, the utility will behave as if none of the variables had been defined.
- If set to a non-empty string value, override the values of all the other internationalisation variables.
- Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single- as opposed to multi-byte characters in arguments).
- Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
- Determine the location of message catalogues for the processing of LC_MESSAGES .
The standard output is used when no blocks operand is present. If the current number of blocks is limited, the number of blocks in the current limit is written in the following format:
"%d\n", <number of 512-byte blocks>
If there is no current limit on the number of blocks, in the POSIX locale the following format is used:
Used only for diagnostic messages.
The following exit values are returned:
- Successful completion.
- A request for a higher limit was rejected or an error occurred.
Since ulimit affects the current shell execution environment, it is always provided as a shell regular built-in. If it is called in separate utility execution environment, such as one of the following:it will not affect the file size limit of the caller's environment.
nohup ulimit -f 10000 env ulimit 10000
Once a limit has been decreased by a process, it cannot be increased (unless appropriate privileges are involved), even back to the original system limit.
Set the file size limit to 51,200 bytes:
ulimit -f 100
The XSH specification description of ulimit().