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getconf

system managementLinux/Unix

The getconf command is one of the most frequently used commands in Linux/Unix-like operating systems. getconf Query system configuration variables

See Examples View Syntax

Quick Reference

Command Name:

getconf

Category:

system management

Platform:

Linux/Unix

Basic Usage:

getconf [options] [arguments]

Common Use Cases

Syntax

getconf [options] variable_name [pathname]

Options

Option	Description
`-a`	Display all configuration variables for the system
`-v specification`	Display values for a specific POSIX specification (e.g., POSIX_V7)
`--help`	Display help information and exit
`--version`	Display version information and exit

Examples

How to Use These Examples

The examples below show common ways to use the getconf command. Try them in your terminal to see the results. You can copy any example by clicking on the code block.

Basic Examples:

getconf PATH

Display the standard PATH for the system.

getconf PAGESIZE

Display the system page size in bytes.

getconf NAME_MAX /tmp

Display the maximum length of a filename in the /tmp directory.

Advanced Examples:

getconf -a List all configuration variables and their values. getconf PATH_MAX /home Display the maximum length of a relative pathname when /home is the current directory. getconf LONG_BIT Display the number of bits in a long integer. getconf OPEN_MAX Display the maximum number of files a process can have open. getconf -v POSIX_V7 SYMLOOP_MAX Display the value of SYMLOOP_MAX for POSIX.1-2008.

Try It Yourself

Practice makes perfect! The best way to learn is by trying these examples on your own system with real files.

Understanding Syntax

Pay attention to the syntax coloring: commands, options, and file paths are highlighted differently.

Notes

The getconf command provides a way to query system configuration variables, which helps in creating portable scripts and applications that need to adapt to different system environments. Key features of getconf: 1. System Configuration Access: getconf provides access to system-specific configuration variables defined in POSIX and other standards, without requiring direct access to system headers or constants. 2. Portability Support: It allows scripts to query system limits and capabilities at runtime, which is essential for portable software development across different Unix-like systems. 3. Filesystem Information: When used with a pathname argument, getconf can retrieve filesystem-specific information such as maximum filename length or pathname length for the specified filesystem. 4. Standards Compliance: With the -v option, getconf can report values based on specific POSIX or other standards versions, which helps in developing software that targets specific compatibility levels. 5. Comprehensive Information: The -a option provides a complete list of all configuration variables available on the system, which is useful for system exploration and debugging. 6. Performance Tuning: Many variables accessible through getconf are relevant for performance tuning, such as memory page size, number of processors, or maximum process limits. 7. Shell Script Integration: The command is designed to be easily used in shell scripts, with output format suitable for capture in variables or parsing. Common use cases for getconf include checking system limits before operations that might exceed them, adapting program behavior based on system capabilities, retrieving filesystem-specific information, and writing portable shell scripts that need to handle different system environments.

Related Commands

These commands are frequently used alongside getconf or serve similar purposes:

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Use Cases

Learn By Doing

The best way to learn Linux commands is by practicing. Try out these examples in your terminal to build muscle memory and understand how the getconf command works in different scenarios.

See Examples Try Lab Exercises

$ getconf

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