getconf Command

Purpose

Writes system configuration variable values to standard output.

Syntax

getconf [ -v specification ] [ SystemwideConfiguration | PathConfiguration PathName ] [ DeviceVariable DeviceName ]

getconf -a

Description

The getconf command, invoked with the SystemwideConfiguration parameter, writes the value of the variable, as specified by the SystemwideConfiguration parameter, to standard output.

The getconf command, invoked with the PathConfiguration and Pathname parameters, writes the value of the variable, as specified by the PathConfiguration parameter for the path specified by the PathName parameter, to standard output.

The getconf command, invoked with the -a flag, writes the values of all system configuration variables to standard output.

The getconf command, invoked with the DeviceVariable and DeviceName parameters, writes the value of the disk device name or location, for the device path specified by the DeviceName parameter, to the standard output.

If the specified variable is defined on the system and its value is described to be available from the confstr subroutine, the value of the specified variable is written in the following format:

"%s\n", <value>

Otherwise, if the specified variable is defined on the system, its value is written in the following format:

"%d\n", <value>

If the specified variable is valid but undefined on the system, the following is written to standard output:

"undefined\n"

If the variable name is invalid or an error occurs, a diagnostic message is written to the standard error.

Flags

Item	Description
-v specification	Indicates a specific specification and version for which configuration variables are to be determined. If this flag is not specified, the values returned will correspond to an implementation default XBS5 conforming compilation environment.
-a	Writes the values of all system configuration variables to standard output.

Parameters

Item	Description
PathName	Specifies a path name for the PathConfiguration parameter.
SystemwideConfiguration	Specifies a system configuration variable.
PathConfiguration	Specifies a system path configuration variable.
DeviceName	Specifies the path name of a device.
DeviceVariable	Specifies a device variable.

When the symbol listed in the first column of the following table is used as the system_var operand, getconf will yield the same value as confstr when called with the value in the second column:

Note: The _CS_AIX_ARCHITECTURE and _CS_AIX_BOOTDEV variables, used as parameters to confstr, are available only to the root user.

system_var	confstr Name Value
BOOT_DEVICE	_CS_AIX_BOOTDEV
MACHINE_ARCHITECTURE	_CS_AIX_ARCHITECTURE
MODEL_CODE	_CS_AIX_MODEL_CODE
PATH	_CS_PATH
XBS5_ILP32_OFF32_CFLAGS	_CS_XBS5_ILP32_OFF32_CFLAGS
XBS5_ILP32_OFF32_LDFLAGS	_CS_XBS5_ILP32_OFF32_LDFLAGS
XBS5_ILP32_OFF32_LIBS	_CS_XBS5_ILP32_OFF32_LIBS
XBS5_ILP32_OFF32_LINTFLAGS	_CS_XBS5_ILP32_OFF32_LINTFLAGS
XBS5_ILP32_OFFBIG_CFLAGS	_CS_XBS5_ILP32_OFFBIG_CFLAGS
XBS5_ILP32_OFFBIG_LDFLAGS	_CS_XBS5_ILP32_OFFBIG_LDFLAGS
XBS5_ILP32_OFFBIG_LIBS	_CS_XBS5_ILP32_OFFBIG_LIBS
XBS5_ILP32_OFFBIG_LINTFLAGS	_CS_XBS5_ILPBIG_OFF32_LINTFLAGS
XBS5_LP64_OFF64_CFLAGS	_CS_XBS5_LP64_OFF64_CFLAGS
XBS5_LP64_OFF64_LDFLAGS	_CS_XBS5_LP64_OFF64_LDFLAGS
XBS5_LP64_OFF64_LIBS	_CS_XBS5_LP64_OFF64_LIBS
XBS5_LP64_OFF64_LINTFLAGS	_CS_XBS5_LP64_OFF64_LINTFLAGS
XBS5_LPBIG_OFFBIG_CFLAGS	_CS_XBS5_LPBIG_OFFBIG_CFLAGS
XBS5_LPBIG_OFFBIG_LDFLAGS	_CS_XBS5_LPBIG_OFFBIG_LDFLAGS
XBS5_LPBIG_OFFBIG_LIBS	_CS_XBS5_LPBIG_OFFBIG_LIBS
XBS5_LPBIG_OFFBIG_LINTFLAGS	_CS_XBS5_LPBIG_OFFBIG_LINTFLAGS

Environment Variables

The following environment variables affect the execution of getconf:

Item	Description
`LANG`	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.
`LC_CALL`	If set to a non-empty string value, override the values of all the other internationalisation variables.
`LC_CTYPE`	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).
`LC_MESSAGES`	Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
`NLSPATH`	Determine the location of message catalogues for the processing of LC_MESSAGES.

Systemwide Configuration Variables

The SystemwideConfiguration parameter specifies system configuration variables whose values are valid throughout the system. There are two kinds of system configuration variables:

Systemwide configuration variables
System standards configuration variables

Systemwide Configuration Variables

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

Item	Description
_CS_PATH	Value for the PATH environment variable used to find commands.
ARG_MAX	Maximum length, in bytes, of the arguments for one of the exec subroutines, including environment data.
BC_BASE_MAX	Maximum value allowed for the obase variable with the bc command.
BC_DIM_MAX	Maximum number of elements permitted in an array by the bc command.
BC_SCALE_MAX	Maximum value allowed for the scale variable with the bc command.
BC_STRING_MAX	Maximum length of a string constant accepted by the bc command.
CHARCLASS_NAME_MAX	Maximum number of bytes in a character class name.
CHAR_BIT	Number of bits in a type character.
CHAR_MAX	Maximum value of a type character.
CHAR_MIN	Minimum value of a type character.
CHILD_MAX	Maximum number of simultaneous processes for each real user ID.
CLK_TCK	Number of clock ticks per second returned by the time subroutine.
COLL_WEIGHTS_MAX	Maximum number of weights that can be assigned to an entry in the LC_COLLATE locale stanza in a locale-definition file.
CS_PATH	Value of the PATH environment variable used to find commands.
EXPR_NEST_MAX	Maximum number of expressions that can be nested within parentheses by the expr command.
INT_MAX	Maximum value of a type int.
INT_MIN	Minimum value of a type int.
LINE_MAX	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 new-line character.
LONG_BIT	Number of bits in a type long int.
LONG_MAX	Maximum value of a type long int.
LONG_MIN	Minimum value of a type long int.
MB_LEN_MAX	Maximum number of bytes in a character for any supported locale.
NGROUPS_MAX	Maximum number of simultaneous supplementary group IDs for each process.
NL_ARGMAX	Maximum value of digit in calls to the printf and scanf subroutines.
NL_LANGMAX	Maximum number of bytes in a LANG name.
NL_MSGMAX	Maximum message number.
NL_NMAX	Maximum number of bytes in an N-to-1 collation mapping.
NL_SETMAX	Maximum set number.
NL_TEXTMAX	Maximum number of bytes in a message string.
NZERO	Default process priority.
OPEN_MAX	Maximum number of files that one process can have open at one time.
PATH	Sequence of colon-separated path prefixes used to find commands.
RE_DUP_MAX	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	Maximum value of a type signed char.
SCHAR_MIN	Minimum value of a type signed char.
SHRT_MAX	Maximum value of a type short.
SHRT_MIN	Minimum value of a type short.
SSIZE_MAX	Maximum value of an object of type ssize_t.
STREAM_MAX	Number of streams that one process can have open at one time.
TMP_MAX	Minimum number of unique path names generated by the tmpnam subroutine. Maximum number of times an application can reliably call the tmpnam subroutine.
TZNAME_MAX	Maximum number of bytes supported for the name of a time zone (not the length of the TZ environment variable).
UCHAR_MAX	Maximum value of a type unsigned char.
UINT_MAX	Maximum value of a type unsigned int.
ULONG_MAX	Maximum value of a type unsigned long int.
USHRT_MAX	Maximum value of a type unsigned short int.
WORD_BIT	Number of bits in a word or type int.
KERNEL_BITMODE	Bit mode of the kernel, 32-bit or 64-bit.
REAL_MEMORY	Real memory size.
HARDWARE_BITMODE	Bit mode of the machine hardware, 32-bit or 64-bit.
MP_CAPABLE	MP-capability of the machine.

System Standards Configuration Variables

System standards configuration variables contain the minimum values required by a particular system standard. The _POSIX_, POSIX2_, and _XOPEN_ prefixes indicate that the variable contains the minimum value for a system characteristic required by the POSIX 1003.1, POSIX 1003.2, and X/Open system standards, respectively. System standards are systemwide 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:

Item	Description
_POSIX_ARG_MAX	Maximum length, in bytes, of the arguments for one of the exec subroutines, including environment data.
_POSIX_CHILD_MAX	Maximum number of simultaneous processes for each real user ID.
_POSIX_JOB_CONTROL	Value of 1 if the system supports job control.
_POSIX_LINK_MAX	Maximum number of links to a single file.
_POSIX_MAX_CANON	Maximum number of bytes in a terminal canonical input queue.
_POSIX_MAX_INPUT	Maximum number of bytes allowed in a terminal input queue.
_POSIX_NAME_MAX	Maximum number of bytes in a file name (not including terminating null).
_POSIX_NGROUPS_MAX	Maximum number of simultaneous supplementary group IDs for each process.
_POSIX_OPEN_MAX	Maximum number of files that one process can have open at one time.
_POSIX_PATH_MAX	Maximum number of bytes in a path name.
_POSIX_PIPE_BUF	Maximum number of bytes guaranteed to be atomic when writing to a pipe.
_POSIX_SAVED_IDS	Value of 1. Each process has a saved set-user-ID and a saved set-group-ID.
_POSIX_SSIZE_MAX	Maximum value that can be stored in an object of type ssize_t.
_POSIX_STREAM_MAX	Number of streams that one process can have open at one time.
_POSIX_TZNAME_MAX	Maximum number of bytes supported for the name of a time zone (not the length of the TZ environment variable).
_POSIX_VERSION	Version of the POSIX 1 standard (C Language Binding) to which the operating system conforms.
_XOPEN_CRYPT	Value of 1 if the system supports the X/Open Encryption Feature Group.
_XOPEN_ENH_I18N	Value of 1 if the system supports the X/Open Enhanced Internationalisation Feature Group.
_XOPEN_SHM	Value of 1 if the system supports the X/Open Shared Memory Feature Group.
_XOPEN_VERSION	Version of the X/Open Portability Guide to which the operating system conforms.
_XOPEN_XCU_VERSION	Version of the X/Open Commands and Utilities specification to which the operating system conforms.
_XOPEN_XPG2	Value of 1 if the system supports the X/Open Portability Guide, Volume 2, January 1987, XVS System Calls and Libraries, otherwise undefined.
_XOPEN_XPG3	Value of 1 if the system supports the X/Open Specification, February 1992, System Interfaces and Headers, Issue 3, otherwise undefined.
_XOPEN_XPG4	Value of 1 if the system supports the X/Open CAE Specification, July 1992, System Interfaces and Headers, Issue 4, otherwise undefined.
POSIX2_BC_BASE_MAX	Maximum value allowed for the obase variable with the bc command.
POSIX2_BC_DIM_MAX	Maximum number of elements permitted in an array by the bc command.
POSIX2_BC_SCALE_MAX	Maximum value allowed for the scale variable with the bc command.
POSIX2_BC_STRING_MAX	Maximum length of a string constant accepted by the bc command.
POSIX2_CHAR_TERM	Value of 1 if the system supports at least one terminal type; otherwise it has the value -1.
POSIX2_COLL_WEIGHTS_MAX	Maximum number of weights that can be assigned to an entry of the LC_COLLATE locale variable in a locale-definition file.
POSIX2_C_BIND	Value of 1 if the system supports the C Language Binding Option from POSIX 2; otherwise, it has the value -1.
POSIX2_C_DEV	Value of 1 if the system supports the C Language Development Utilities from POSIX 2; otherwise, it has the value -1.
POSIX2_C_VERSION	Version of the POSIX 2 standard (C Language Binding) to which the operating system conforms.
POSIX2_EXPR_NEST_MAX	Maximum number of expressions that can be nested within parentheses by the expr command.
POSIX2_FORT_DEV	Value of 1 if the system supports the FORTRAN Development Utilities Option from POSIX 2; otherwise, it has the value -1.
POSIX2_FORT_RUN	Value of 1 if the system supports the FORTRAN Runtime Utilities Option from POSIX 2; otherwise, it has the value -1.
POSIX2_LINE_MAX	The maximum length, in bytes, of a command's input line (either standard input or another file) when the command is described as processing text files. The length includes room for the trailing new-line character.
POSIX2_LOCALEDEF	Value of 1 if the system supports the creation of the locales by the localedef command; otherwise, it is undefined.
POSIX2_RE_DUP_MAX	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_SW_DEV	Value of 1 if the system supports the Software Development Utilities Option; otherwise, it has the value -1.
POSIX2_UPE	Value of 1 if the system supports the User Portability Utilities Option from POSIX 2; otherwise, it as the value -1.
POSIX2_VERSION	Date of approval of the most current version of the POSIX 2 standard that the system supports. The date is a six-digit number, with the first four digits signifying the year and the last two 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.

System Path Configuration Variables

The PathConfiguration parameter specifies system path configuration variables whose values contain information about paths and path structures in the system. The following list defines these variables:

Item	Description
_POSIX_CHOWN_RESTRICTED	The chown() subroutine is restricted to a process with appropriate privileges, and to changing the group ID of a file only to the effective group ID of the process or to one of its supplementary group IDs. If the PathName parameter refers to a directory, the value returned applies to any files except directories that exist or can be created within the directory.
_POSIX_NO_TRUNC	Path names longer than the limit specified by the NAME_MAX variable will generate an error. If the PathName parameter refers to a directory, the value returned applies to file names within the directory.
_POSIX_VDISABLE	Terminal special characters, defined in the termios.h file, can be disabled using this character value.
LINK_MAX	Maximum number of links to a single file. If the PathName parameter refers to a directory, the value returned applies to the directory.
MAX_CANON	Maximum number of bytes in a terminal canonical input line.
MAX_INPUT	Maximum number of bytes for which space is available in a terminal input queue.
NAME_MAX	Maximum number of bytes in a file name (not including terminating null). If the PathName parameter refers to a directory, the value returned applies to the file names within the directory.
PATH_MAX	Maximum number of bytes in a path name, including the terminating null character. If the PathName parameter refers to a directory, the value returned is the maximum length of a relative path name when the specified directory is the working directory.
PIPE_BUF	Maximum number of bytes guaranteed to be atomic when writing to a pipe. If the PathName parameter refers to a FIFO or a pipe, the value returned applies to the referenced object. If the PathName parameter refers to a directory, the value returned applies to any FIFO that exists or can be created within the directory.
DISK_PARTITION	Physical partition size of the disk. Note: For the DISK_PARTITION path configuration variable, the PathName parameter must specify the complete path of the disk for which information is being queried.
DISK_SIZE	Disk size in megabytes. Note: For the DISK_SIZE path configuration variable, the PathName parameter must specify the complete path of the disk for which information is being queried.

Device Variables

The DeviceVariable parameter indicates that the DeviceName parameter is the path of a device, such as /dev/hdisk0. Given the path of a disk, the getconf command displays the device name or location of the disk.

Item	Description
DISK_DEVNAME	Device name or location of the device.

Exit Status

This command returns the following exit values:

Item	Description
0	The specified variable is valid and information about its current state was successfully written.
>0	An error occurred.

To display the value of the ARG_MAX variable, type:
```
getconf ARG_MAX
```
To display the values of all system configuration variables, type:
```
 getconf -a
```
To display the value of the NAME_MAX variable for the /usr directory, type:
```
 
getconf NAME_MAX /usr
```

The following sequence of shell commands shows how to handle unspecified results:

if value=$(getconf PATH_MAX /usr)
then
     if [ "$value" = "undefined" ]
     then
                echo 
                     The value of PATH_MAX in /usr is undefined.
     else

                     The value of PATH_MAX in /usr is $value.
     fi
else
                echo
                     Error in the getconf command.
fi

Examples

To display the value of the ARG_MAX variable, enter the following command::
```
getconf ARG_MAX
```
To display the value of the NAME_MAX variable for the /usr directory, enter the following command:
```
getconf NAME_MAX /usr
```

The following sequence of shell commands shows how to handle unspecified results:

if value=$(getconf PATH_MAX /usr)
then
     if [ "$value" = "undefined" ]
     then
             echo
                   The value of PATH_MAX in /usr is undefined.
     else
             echo 
                   The value of PATH_MAX in /usr is $value.
     fi
else
     echo Error in the getconf command.
fi

If the command:
```
getconf _XBS5_ILP32_OFF32 
```
does not write -1\n or undefined\n to standard output, then commands of the form:
```
getconf -v XBS5_ILP32_OFF32 ... 
```
determine values for configuration variables corresponding to the XBS5_ILP32_OFF32 compilation environment specified in c89, Extended Description.
If the command:
```
getconf _XBS5_ILP32_OFFBIG 
```
does not write -1\n or undefined\n to standard output, then commands of the form:
```
getconf -v XBS5_ILP32_OFFBIG ... 
```
determine values for configuration variables corresponding to the XBS5_ILP32_OFFBIG compilation environment specified in c89, Extended Description.
If the command:
```
getconf _XBS5_LP64_OFF64 
```
does not write -1\n or undefined\n" to standard output, then commands of the | form:
```
getconf -v XBS5_LP64_OFF64 ... 
```
determine values for configuration variables corresponding to the XBS5_LP64_OFF64 compilation environment specified in c89, Extended Description.
If the command:
```
getconf _XBS5_LPBIG_OFFBIG 
```
does not write -1\n or undefined\n to standard output, then commands of the form:
```
getconf -v _XBS5_LPBIG_OFFBIG 
```
determine values for configuration variables corresponding to the XBS5_LPBIG_OFFBIG compilation environment specified in c89, Extended Description.
To determine the disk size for disk hdisk0, as root user, enter the following command:
```
getconf DISK_SIZE /dev/hdisk0
```
To determine the real memory size, enter the following command:
```
getconf REAL_MEMORY
```
To determine if the machine hardware is 32-bit or 64-bit, enter the following command:
```
getconf HARDWARE_BITMODE
```
To determine if the kernel is 32-bit or 64-bit, enter the following command:
```
getconf KERNEL_BITMODE
```
To determine the device name or location of disk hdisk0, enter the following command:
```
getconf DISK_DEVNAME hdisk0
```

Files

Item	Description
/usr/bin/getconf	Contains the getconf command.
/usr/include/limits.h	Defines system configuration variables.
/usr/include/unistd.h	Defines system configuration variables.