getconf

POSIX system configuration variable query tool

TLDR

List all configuration values available

$ getconf -a

List the configuration values for a specific directory

$ getconf -a [path/to/directory]

Check if the system is 32-bit or 64-bit

$ getconf LONG_BIT

Check how many processes the current user can run at once

$ getconf CHILD_MAX

List every configuration value and filter with grep

$ getconf -a | grep MAX

SYNOPSIS

getconf [-v spec] systemvar_getconf [-v spec] pathvar pathname_

getconf retrieves system configuration variables defined by POSIX and system-specific extensions. These values represent system limits and capabilities that applications can query to adapt their behavior.Variables fall into two categories: system-wide values (like CHILDMAX, PAGESIZE) and pathname-specific values (like PATHMAX, NAMEMAX) that may vary by filesystem.This is useful for shell scripts that need to query system limits without hardcoding values, ensuring portability across different systems.

PARAMETERS

-a

Display all configuration variables and their values

-v SPEC

Use specification SPEC for configuration values

LONG_BIT

Number of bits in a long integer (32 or 64)

CHILD_MAX

Maximum number of processes per user

OPEN_MAX

Maximum number of files a process can have open

PAGE_SIZE

System memory page size in bytes

PATH_MAX

Maximum length of a file path

HOST_NAME_MAX

Maximum length of a hostname

ARG_MAX

Maximum length of arguments to the exec functions

_NPROCESSORS_CONF

Number of processors configured

_NPROCESSORS_ONLN

Number of processors currently online

INSTALL

sudo apt install libc-bin

sudo apk add musl-utils

nix profile install nixpkgs#getconf

CAVEATS

Some values may be indeterminate (shown as "undefined"). Pathname-specific variables can return different values for different filesystems. Not all variables are supported on all systems.

HISTORY

getconf is part of the POSIX standard and has been available on Unix-like systems since the early 1990s. It provides a standardized way to query the same configuration values that the C functions sysconf(), pathconf(), and confstr() return.