getrlimit
TLDR
Get resource limits (shell)
$ ulimit -a
Get specific limit (shell)$ ulimit -n
SYNOPSIS
#include <sys/resource.h>
int getrlimit(int resource, struct rlimit \*rlim);
int setrlimit(int resource, const struct rlimit \*rlim);
DESCRIPTION
getrlimit() and setrlimit() are system calls for querying and setting resource limits for the calling process. These limits control maximum values for various system resources.
The ulimit shell built-in provides command-line access to these limits. Limits have soft (current) and hard (maximum) values.
PARAMETERS
resource
Resource type (RLIMITNOFILE, RLIMITNPROC, etc.).rlim
Pointer to rlimit structure with soft/hard limits.
RESOURCES
$ RLIMIT_NOFILE - Maximum open files
RLIMIT_NPROC - Maximum processes
RLIMIT_AS - Maximum address space
RLIMIT_CORE - Maximum core file size
RLIMIT_STACK - Maximum stack size
RLIMIT_DATA - Maximum data segment
RLIMIT_FSIZE - Maximum file size
RLIMIT_CPU - CPU time limit
RLIMIT_MEMLOCK - Maximum locked memory
RLIMIT_NPROC - Maximum processes
RLIMIT_AS - Maximum address space
RLIMIT_CORE - Maximum core file size
RLIMIT_STACK - Maximum stack size
RLIMIT_DATA - Maximum data segment
RLIMIT_FSIZE - Maximum file size
RLIMIT_CPU - CPU time limit
RLIMIT_MEMLOCK - Maximum locked memory
SHELL ACCESS
$ ulimit -n # Open files
ulimit -u # Max processes
ulimit -s # Stack size
ulimit -a # All limits
ulimit -n 4096 # Set open files limit
ulimit -u # Max processes
ulimit -s # Stack size
ulimit -a # All limits
ulimit -n 4096 # Set open files limit
CAVEATS
System call, not a command. Non-root users cannot raise hard limits. Some limits affect child processes. PAM may set limits at login.
SEE ALSO
ulimit(1), prlimit(1), limits.conf(5)
