NAME

getconf - Displays system configuration variable values

SYNOPSIS

getconf system_configuration getconf path_configuration pathname

DESCRIPTION

The system_configuration argument specifies a system-wide configuration variable.  The path_configuration argument specifies a system path-configuration variable.   The pathname argument specifies a pathname for the path_configuration variable. 

The system_configuration argument specifies system-configuration variables whose values are valid throughout the system.  There are two kinds of system-wide configuration values:

       •System-wide configuration variables

       •System standards configuration variables

The path_configuration argument specifies system path-configuration variables whose values contain information about paths and the path structure in the system. 

System-Wide Configuration Variables

System-wide configuration variables contain the minimum values met throughout all portions of the system. The following list defines the system-wide configuration variables used with the getconf command:

ARG_MAX
The maximum length, in bytes, of the arguments for one of the exec functions, including environment data. 

ATEXIT_MAX
The maximum number of functions that can be registered with atexit() per process. 

BC_BASE_MAX
The maximum value allowed for the obase variable with the bc command. 

BC_DIM_MAX
The maximum number of elements permitted in an array by the bc command. 

BC_SCALE_MAX
The maximum value allowed for the scale variable with the bc command. 

BC_STRING_MAX
The maximum length of string constants accepted by the bc command. 

CHARCLASS_NAME_MAX
The maximum number of bytes in a character class name.

CHAR_BIT
Number of bits in a type of char.

CHAR_MAX
The maximum value of a type char.

CHAR_MIN
The minimum value of a type char.

CHILD_MAX
The maximum number of simultaneous processes for each real user ID.

CLK_TCK
The number of clock ticks per second.  The value of CLK_TCK may be variable, and it should not be assumed that CLK_TCK is a compile-time constant. 

COLL_WEIGHTS_MAX
The maximum number of weights that can be assigned to an entry in the LC_COLLATE locale-dependent information in a locale-definition file. 

CS_PATH
A value for the PATH environment variable that finds all standard utilities. 

DATAKEYS_MAX
The maximum number of data keys that may be created per process.

EXPR_NEST_MAX
The maximum number of expressions that can be nested within parentheses by the expr command. 

INT_MAX
The maximum value of an int.

INT_MIN
The minimum value of an int.

LINE_MAX
The maximum length, in bytes, of a command’s input line (either standard input or another file) when the utility is described as processing text files. The length includes room for the trailing newline character.

LONG_BIT
Number of bits in a long int.

LONG_MAX
The maximum value of a long int.

LONG_MIN
The minimum value of a long int.

MB_LEN_MAX
The maximum number of bytes in a character for any supported locale.

NGROUPS_MAX
The maximum number of simultaneous supplementary group IDs for each process.

NL_ARGMAX
The maximum value of digit in calls to the printf() and scanf() functions.

NL_LANGMAX
The maximum number of bytes in a LANG name.

NL_MSGMAX
The maximum message number.

NL_NMAX
The maximum number of bytes in an N-to-1 collation mapping.

NL_SETMAX
The maximum set number.

NL_TEXTMAX
The maximum number of bytes in a message string.

NZERO
Default process priority.

OPEN_MAX
The maximum number of files that one process can have open at one time.

PAGE_SIZE
The page size granularity for memory regions.

PASS_MAX
The maximum number of characters returned by getpass() (not including terminating null). 

PATHA value for the PATH environment variable that finds all standard utilities. 

RE_DUP_MAX
The maximum number of repeated occurrences of a regular expression permitted when using the interval-notation parameters, such as the m and n parameters with the ed command. 

SCHAR_MAX
The maximum value of a type signed char.

SCHAR_MIN
The minimum value of a type signed char.

SHRT_MAX
The maximum value of a type short.

SHRT_MIN
The minimum value of a type short.

STREAM_MAX
The number of streams that one process can have open at one time.

TMP_MAX
The minimum number of unique pathnames generated by tmpnam(). Maximum number of times an application can call tmpnam() reliably.

TZNAME_MAX
The maximum number of bytes supported for the name of a time zone (not the length of the TZ environmental variable). 

UCHAR_MAX
The maximum value of a type unsigned char.

UINT_MAX
The maximum value of a type unsigned int.

ULONG_MAX
The maximum value of a type unsigned long int.

USHRT_MAX
The maximum value of a type unsigned short int.

WORD_BIT
Number of bits in a word or type int.

System Standards Configuration Variables

System standards configuration variables contain the minimum values required by a particular system standard. The prefixes _POSIX_, POSIX2_, _XOPEN, and _AES indicate that the variable contains the minimum value for a system characteristic required by the POSIX 1003.1, POSIX 1003.2, X/Open, and OSF/1 AES system standards, respectively.  System standards are system-wide minimums that the system meets to support the particular system standard. Actual configuration values may exceed these standards. The system standards configuration variables for the getconf command are defined as follows:

_AES_OS_VERSION
The integer value indicating the revision of the Application Environment Specification to which the implementation is compliant.

_POSIX_ARG_MAX
The length of the arguments for one of the exec functions, in bytes, including environment data. 

_POSIX_CHILD_MAX
The maximum number of simultaneous processes for each real user ID.

_POSIX_JOB_CONTROL
This variable has a value of 1 if the system supports job control; otherwise, the variable is undefined.

_POSIX_LINK_MAX
The maximum value of a file’s link count.

_POSIX_LOCALEDEF
This variable has a value of 1 if the system restricts supported locales to only those it supplies; otherwise, the variable has a value of 0 (zero).

_POSIX_MAX_CANON
The maximum number of bytes in a terminal canonical input queue.

_POSIX_MAX_INPUT
The maximum number of bytes for which space will be available in a terminal input queue.

_POSIX_NAME_MAX
The maximum number of bytes in a filename.

_POSIX_NGROUPS_MAX
The maximum number of simultaneous supplementary group IDs for each process.

_POSIX_OPEN_MAX
The maximum number of files that one process can have open at one time.

_POSIX_PATH_MAX
The maximum number of bytes in a pathname.

_POSIX_PIPE_BUF
The maximum number of bytes that can be written atomically when writing to a pipe.

_POSIX_REENTRANT_FUNCTIONS
This variable has a value of 1 if the system supports POSIX reentrant functions; otherwise, the variable is undefined.

_POSIX_SAVED_IDS
This variable has a value of 1 if each process has a saved set-user-ID and a saved set-group-ID; otherwise, the variable is undefined.

_POSIX_SSIZE_MAX
The maximum value that can be stored in an object of type ssize_t. 

_POSIX_STREAM_MAX
The number of streams that one process can have open at one time.

_POSIX_THREAD_ATTR_STACKSIZE
This variable has a value of 1 if the system supports the POSIX threads stack size attribute; otherwise, the variable is undefined.

_POSIX_THREADS
This variable has a value of 1 if the system supports POSIX threads; otherwise, the variable is undefined.

_POSIX_TZNAME_MAX
The maximum number of bytes supported for the name of a time zone (not the length of the TZ environmental variable). 

_POSIX_VERSION
The date of approval of the most current version of the POSIX 1 standard that the system supports. The date is a 6-digit number, with the first 4 digits signifying the year and the last 2 digits the month. Different versions of the POSIX 1 standard are periodically approved by the IEEE Standards Board, and the date of approval is used to distinguish between different versions.

POSIX2_BC_BASE_MAX
The maximum value allowed for the obase variable with the bc command. 

POSIX2_BC_DIM_MAX
The maximum number of elements permitted in an array by the bc command. 

POSIX2_BC_SCALE_MAX
The maximum value allowed for the scale variable with the bc command. 

POSIX2_BC_STRING_MAX
The maximum length string constants accepted by the bc command. 

POSIX2_CHAR_TERM
One or more terminal types capable of all operations described in ISO/IEC 9945.  This value need not be present on a system not supporting the User Portability Utilities Option.

POSIX2_COLL_WEIGHTS_MAX
The maximum number of weights that can be assigned to an entry of the LC_COLLATE locale variable in a locale-definition file. 

POSIX2_EXPR_NEST_MAX
The maximum number of expressions that can be nested within parentheses by the expr command. 

POSIX2_LINE_MAX
The maximum length, in bytes, of a command’s input line (either standard input or another file) when the utility is described as processing text files. The length includes room for the trailing newline character.

POSIX2_RE_DUP_MAX
The maximum number of repeated occurrences of a regular expression permitted when using the interval-notation parameters, such as the m and n parameters with the ed command. 

POSIX2_UPE
This variable has a value of 1 if the system supports the User Portability Utilities Option; otherwise, the variable has a value of 0 (zero).

POSIX2_VERSION
The date of approval of the most current version of the POSIX 2 standard that the system supports. The date is a 6-digit number, with the first 4 digits signifying the year and the last 2 digits the month. Different versions of the POSIX 2 standard are periodically approved by the IEEE Standards Board, and the date of approval is used to distinguish between different versions.

POSIX2_C_BIND
This variable has a value of 1 if the system supports the optional C Language Development Facilities specified by POSIX 2 and the optional C Language Bindings Option from POSIX 2; otherwise, the variable is undefined.

POSIX2_C_DEV
This variable has a value of 1 if the system supports the optional C Language Development Utilities from POSIX 2; otherwise, the variable is undefined.

POSIX2_C_VERSION
The integer value 199209L.  This value indicates the version of the interfaces described in the C-Language Bindings Option section of the XPG4 standard. This value changes with each published version of ISO/IEC 9945 to indicate the 4-digit year and 2-digit month that the standard was approved by the IEEE Standards Board.

POSIX2_FORT_DEV
This variable has a value of 1 if the system supports the FORTRAN Development Utilities Option from POSIX 2; otherwise, the variable is undefined.

POSIX2_FORT_RUN
This variable has a value of 1 if the system supports the FORTRAN Runtime Utilities Option from POSIX 2; otherwise, the variable is undefined.

POSIX2_LOCALEDEF
This variable has a value of 1 if the system supports the creation of new locales with the localedef command; otherwise, the variable is undefined. 

POSIX2_SW_DEV
This variable has a value of 1 if the system supports the Software Development Utilities Option from POSIX 2; otherwise, the variable is undefined.

SSIZE_MAX
The maximum value that can be stored in an object of type ssize_t. 

_XOPEN_CRYPT
To have a value other than -1 if the implementation supports the X/Open Encryption Feature Group.

_XOPEN_ENH_I18N
To have a value other than -1 if the implementation supports the X/Open Enhanced Internationalization Feature Group.

_XOPEN_SHM
To have a value other than -1 if the implementation supports the X/Open Shared Memory Feature Group.

_XOPEN_VERSION
An integer indicating the most current version of the X/OPEN standard that the system supports.

_XOPEN_XCU_VERSION
An integer value indicating the version of the XCU specification to which the implementation conforms. If the value is -1, no commands and utilities are provided on the implementation.

_XOPEN_XPG2
It is defined only if the implementation supports the X/Open Portability Guide, Volume2, January 1987, XVS System Calls and Libraries.

_XOPEN_XPG3
It is defined only if the implementation supports the X/Open Specification, February 1992, System Interfaces and Headers, Issue 3.

_XOPEN_XPG4
It is defined only if the implementation supports the X/Open CAE Specification, July 1992, Systems Interfaces and Headers, Issue 4.

System Path Configuration Variables

LINK_MAX
The maximum value of a file’s link count. If the pathname argument refers to a directory, the value returned applies to the directory itself. 

MAX_CANON
The maximum number of bytes in a terminal canonical input queue. If the pathname argument  does not specify a terminal file, the getconf command exits with a nonzero value. 

MAX_INPUT
The maximum number of bytes for which space will be available in a terminal input queue. If the pathname argument does not specify a terminal file, the getconf command exits with a nonzero value. 

NAME_MAX
The maximum number of bytes in a filename. If the pathname argument specifies a directory, the value returned applies to the filenames within the directory. 

PATH_MAX
The maximum number of bytes in a pathname. If the pathname argument specifies a directory, the value returned is the maximum length of a relative pathname when the specified directory is the working directory. 

PIPE_BUF
The maximum number of bytes that can be written atomically when writing to a pipe. If the pathname argument specifies a FIFO or a pipe, the value returned applies to that object. If the pathname argument specifies a directory, the value returned applies to any FIFO created in that directory. If the pathname argument does not specify a directory or a FIFO file, the getconf command exits with a nonzero value. 

_POSIX_CHOWN_RESTRICTED
This variable has a value of 1 when the use of the chown function is restricted to a process with appropriate privileges and the group ID of a file can only be changed to the effective group ID of the process or to one of its supplementary group IDs. If the variable is undefined, it varies in the system, depending upon the path. 

_POSIX_NO_TRUNC
This variable has a value of 1 when pathnames longer than the limit specified by the NAME_MAX variable will generate an error. If the variable is undefined, it varies in the system, depending upon the path. 

_POSIX_VDISABLE
When this variable has a value of 1, terminal special characters, which are defined in the termios.h header file, can be disabled.  If the pathname argument  does not specify a terminal file, the getconf command will exit with a nonzero value. 

EXAMPLES

     1.To display the value of the ARG_MAX environment variable, enter:

getconf ARG_MAX

     2.To display the value of the PATH_MAX environmental variable for the /usr directory, enter: getconf PATH_MAX /usr

This sequence returns the following message:

The value of PATH_MAX in /usr is 1023

FILES

/usr/include/limits.hDefines system configuration variables. 

/usr/include/unistd.h
Defines system configuration variables.

RELATED INFORMATION

Commands: env(1).