linux command getconf

GETCONF(P)                 POSIX ProgrammerManual                GETCONF(P)

 

NAME

getconf – get configuration values

SYNOPSIS

getconf [ -v specification ] system_var

getconf [ -v specification ] path_var pathname

 

DESCRIPTION

In  the  first  synopsis  form,  the getconf utility shall write to the

standard output the value of the variable specified by  the  system_var

operand.

In  the  second  synopsis  form, the getconf utility shall write to the

standard output the value of the variable  specified  by  the  path_var

operand for the path specified by the pathname operand.

The  value  of each configuration variable shall be determined as if it

were obtained by calling the function from which it is  defined  to  be

available  by  this  volume  of  IEEE Std 1003.1-2001  or by the System

Interfaces volume of IEEE Std 1003.1-2001 (see the  OPERANDS  section).

The  value  shall  reflect conditions in the current operating environ-

ment.

OPTIONS

The getconf utility shall conform to the  Base  Definitions  volume  of

IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.

The following option shall be supported:

-v  specification

Indicate a specific specification and version for which configu-

ration variables shall be determined.  If  this  option  is  not

specified,  the  values returned correspond to an implementation

default conforming compilation environment.

If the command:

 

getconf _POSIX_V6_ILP32_OFF32

does not write “-1
” or “undefined
” to standard  output,  then  com-

mands of the form:

 

getconf -v POSIX_V6_ILP32_OFF32 …

determine  values  for  configuration  variables  corresponding  to the

POSIX_V6_ILP32_OFF32 compilation environment specified  in  c99  ,  the

EXTENDED DESCRIPTION.

If the command:

 

getconf _POSIX_V6_ILP32_OFFBIG

does  not  write  ”-1
” or “undefined
” to standard output, then com-

mands of the form:

 

getconf -v POSIX_V6_ILP32_OFFBIG …

determine values  for  configuration  variables  corresponding  to  the

POSIX_V6_ILP32_OFFBIG  compilation  environment  specified in c99 , the

EXTENDED DESCRIPTION.

If the command:

 

getconf _POSIX_V6_LP64_OFF64

does not write “-1
” or “undefined
” to standard  output,  then  com-

mands of the form:

 

getconf -v POSIX_V6_LP64_OFF64 …

determine  values  for  configuration  variables  corresponding  to the

POSIX_V6_LP64_OFF64 compilation environment  specified  in  c99  ,  the

EXTENDED DESCRIPTION.

If the command:

 

getconf _POSIX_V6_LPBIG_OFFBIG

does  not  write  ”-1
” or “undefined
” to standard output, then com-

mands of the form:

 

getconf -v POSIX_V6_LPBIG_OFFBIG …

determine values  for  configuration  variables  corresponding  to  the

POSIX_V6_LPBIG_OFFBIG  compilation  environment  specified in c99 , the

EXTENDED DESCRIPTION.

 

OPERANDS

The following operands shall be supported:

path_var

A name of a configuration variable. All of the variables in  the

Variable  column  of  the table in the DESCRIPTION of the fpath-

conf() function defined  in  the  System  Interfaces  volume  of

IEEE Std 1003.1-2001,  without  the  enclosing  braces, shall be

supported.  The implementation may add other local variables.

pathname

A pathname for which the variable specified by path_var is to be

determined.

system_var

A  name  of a configuration variable. All of the following vari-

ables shall be supported:

* The names in the Variable column of the table in the DESCRIP-

TION  of the sysconf() function in the System Interfaces vol-

ume of IEEE Std 1003.1-2001, except for  the  entries  corre-

sponding    to    _SC_CLK_TCK,    _SC_GETGR_R_SIZE_MAX,   and

_SC_GETPW_R_SIZE_MAX, without the enclosing braces.

For compatibility with earlier versions, the following  variable

names shall also be supported:

 

POSIX2_C_BIND

POSIX2_C_DEV

POSIX2_CHAR_TERM

POSIX2_FORT_DEV

POSIX2_FORT_RUN

POSIX2_LOCALEDEF

POSIX2_SW_DEV

POSIX2_UPE

POSIX2_VERSION

and shall be equivalent to the same name prefixed with an under-

score.  This requirement may be removed in a future version.

 

* The names of the symbolic constants used as the name argument

of  the confstr() function in the System Interfaces volume of

IEEE Std 1003.1-2001, without the _CS_ prefix.

 

* The names of the symbolic constants listed under the headings

Maximum  Values and Minimum Values in the description

of the <limits.h> header in the Base  Definitions  volume  of

IEEE Std 1003.1-2001, without the enclosing braces.

For  compatibility with earlier versions, the following variable

names shall also be supported:

 

POSIX2_BC_BASE_MAX

POSIX2_BC_DIM_MAX

POSIX2_BC_SCALE_MAX

POSIX2_BC_STRING_MAX

POSIX2_COLL_WEIGHTS_MAX

POSIX2_EXPR_NEST_MAX

POSIX2_LINE_MAX

POSIX2_RE_DUP_MAX

and shall be equivalent to the same name prefixed with an under-

score.  This requirement may be removed in a future version.

 

The implementation may add other local values.

 

STDIN

Not used.

INPUT FILES

None.

ENVIRONMENT VARIABLES

The  following environment variables shall affect the execution of get-

conf:

LANG   Provide a default value for the  internationalization  variables

that  are  unset  or  null.  (See the Base Definitions volume of

IEEE Std 1003.1-2001, Section  8.2,  Internationalization  Vari-

ables  for the precedence of internationalization variables used

to determine the values of locale categories.)

LC_ALL If set to a non-empty string value, override the values  of  all

the other internationalization variables.

LC_CTYPE

Determine  the  locale  for  the  interpretation of sequences of

bytes of text data as characters (for  example,  single-byte  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 catalogs for the processing of

LC_MESSAGES .

 

ASYNCHRONOUS EVENTS

Default.

STDOUT

If  the  specified  variable  is defined on the system and its value is

described to be available from the confstr() function  defined  in  the

System  Interfaces  volume  of IEEE Std 1003.1-2001, its value shall be

written in the following format:

 

“%s
“, <value>

Otherwise, if the specified variable is  defined  on  the  system,  its

value shall be written in the following format:

 

“%d
“, <value>

If  the  specified  variable  is valid, but is undefined on the system,

getconf shall write using the following format:

 

“undefined

If the variable name is invalid or an error occurs,  nothing  shall  be

written to standard output.

STDERR

The standard error shall be used only for diagnostic messages.

OUTPUT FILES

None.

EXTENDED DESCRIPTION

None.

EXIT STATUS

The following exit values shall be returned:

0     The  specified  variable is valid and information about its cur-

rent state was written successfully.

>0     An error occurred.

 

CONSEQUENCES OF ERRORS

Default.

The following sections are informative.

APPLICATION USAGE

None.

EXAMPLES

The following example illustrates the value of {NGROUPS_MAX}:

 

getconf NGROUPS_MAX

The following example illustrates the value of {NAME_MAX}  for  a  spe-

cific directory:

 

getconf NAME_MAX /usr

The  following  example  shows  how to deal more carefully with results

that might be unspecified:

 

if value=$(getconf PATH_MAX /usr); then

if [ "$value" = "undefined" ]; then

echo PATH_MAX in /usr is infinite.

else

echo PATH_MAX in /usr is $value.

fi

else

echo Error in getconf.

fi

Note that:

 

sysconf(_SC_POSIX_C_BIND);

and:

 

system(“getconf POSIX2_C_BIND”);

in a C program could give different answers. The  sysconf()  call  sup-

plies  a  value that corresponds to the conditions when the program was

either compiled or executed, depending on the implementation; the  sys-

tem()  call  to getconf always supplies a value corresponding to condi-

tions when the program is executed.

RATIONALE

The original need for this utility, and for the confstr() function, was

to provide a way of finding the configuration-defined default value for

the PATH environment variable. Since PATH can be modified by  the  user

to include directories that could contain utilities replacing the stan-

dard utilities, shell scripts need a way to determine  the  system-sup-

plied  PATH environment variable value that contains the correct search

path for the standard utilities. It was later suggested that access  to

the  other  variables  described in this volume of IEEE Std 1003.1-2001

could also be useful to applications.

This functionality of getconf  would  not  be  adequately  subsumed  by

another command such as:

 

grep var /etc/conf

because  such a strategy would provide correct values for neither those

variables that can vary at runtime, nor those that can  vary  depending

on the path.

Early  proposal  versions  of  getconf specified exit status 1 when the

specified variable was valid, but not defined on the system. The output

string  ”undefined”  is  now used to specify this case with exit code 0

because so many things depend on an exit code of zero when  an  invoked

utility is successful.

FUTURE DIRECTIONS

None.

SEE ALSO

c99  , the Base Definitions volume of IEEE Std 1003.1-2001, <limits.h>,

the System Interfaces volume of IEEE Std 1003.1-2001, confstr(),  path-

conf(), sysconf(), system()

COPYRIGHT

Portions  of  this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology

–  Portable  Operating  System  Interface (POSIX), The Open Group Base

Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of

Electrical  and  Electronics  Engineers, Inc and The Open Group. In the

event of any discrepancy between this version and the original IEEE and

The  Open Group Standard, the original IEEE and The Open Group Standard

is the referee document. The original Standard can be  obtained  online

at http://www.opengroup.org/unix/online.html .

 

IEEE/The Open Group                  2003                           GETCONF(P)

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