freebsd-src/usr.bin/getconf/getconf.1

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.Dd September 15, 2017
.Dt GETCONF 1
.Os
.Sh NAME
.Nm getconf
.Nd retrieve standard configuration variables
.Sh SYNOPSIS
.Nm
.Fl a
.Op Ar file
.Nm
.Op Fl v Ar environment
.Ar path_var
.Ar file
.Nm
.Op Fl v Ar environment
.Ar system_var
.Sh DESCRIPTION
The
.Nm
utility prints the values of
.Tn POSIX
or
.Tn X/Open
path or system configuration variables to the standard output.
If a variable is undefined, the string
.Dq Li undefined
is output.
.Pp
The first form of the command displays all of the path or system configuration
variables to standard output.
If
.Ar file
is provided,
all path configuration variables are reported for
.Ar file
using
.Xr pathconf 2 .
Otherwise,
all system configuration variables are reported using
.Xr confstr 3
and
.Xr sysconf 3 .
.Pp
The second form of the command, with two mandatory
arguments, retrieves file- and file system-specific
configuration variables using
.Xr pathconf 2 .
The third form, with a single argument, retrieves system
configuration variables using
.Xr confstr 3
and
.Xr sysconf 3 ,
depending on the type of variable.
As an extension, the second form can also be used to query static limits from
.In limits.h .
.Pp
All
.Xr sysconf 3
and
.Xr pathconf 2
variables use the same name as the manifest constants defined in
the relevant standard C-language bindings, including any leading
underscore or prefix.
That is to say,
.Ar system_var
might be
.Dv ARG_MAX
or
.Dv _POSIX_VERSION ,
as opposed to the
.Xr sysconf 3
names
.Dv _SC_ARG_MAX
or
.Dv _SC_POSIX_VERSION .
Variables retrieved from
.Xr confstr 3
have the leading
.Ql _CS_
stripped off; thus,
.Dv _CS_PATH
is queried by a
.Ar system_var
of
.Dq Li PATH .
.Ss Programming Environments
The
.Fl v Ar environment
option specifies a
.St -p1003.1-2001
programming environment under which the values are to be queried.
This option currently does nothing, but may in the future be used
to select between 32-bit and 64-bit execution environments on platforms
which support both.
Specifying an environment which is not supported on the current execution
platform gives undefined results.
.Pp
The standard programming environments are as follows:
.Bl -tag -width ".Li POSIX_V6_LPBIG_OFFBIG" -offset indent
.It Li POSIX_V6_ILP32_OFF32
Exactly 32-bit integer, long, pointer, and file offset.
.Sy Supported platforms :
None.
.It Li POSIX_V6_ILP32_OFFBIG
Exactly 32-bit integer, long, and pointer; at least 64-bit file offset.
.Sy Supported platforms :
.Tn IA32 ,
.Tn PowerPC .
.It Li POSIX_V6_LP64_OFF64
Exactly 32-bit integer; exactly 64-bit long, pointer, and file offset.
.Sy Supported platforms :
.Tn AMD64 ,
.Tn SPARC64 .
.It Li POSIX_V6_LPBIG_OFFBIG
At least 32-bit integer; at least 64-bit long, pointer, and file offset.
.Sy Supported platforms :
None.
.El
.Pp
The command:
.Pp
.Dl "getconf POSIX_V6_WIDTH_RESTRICTED_ENVS"
.Pp
returns a newline-separated list of environments in which the width
of certain fundamental types is no greater than the width of the native
C type
.Vt long .
At present, all programming environments supported by
.Fx
have this property.
Several of the
.Xr confstr 3
variables provide information on the necessary compiler and linker flags
to use the standard programming environments described above.
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
The command:
.Pp
.Dl "getconf PATH"
.Pp
will display the system default setting for the
.Ev PATH
environment variable.
.Pp
The command:
.Pp
.Dl "getconf NAME_MAX /tmp"
.Pp
will display the maximum length of a filename in the
.Pa /tmp
directory.
.Pp
The command:
.Pp
.Dl "getconf -v POSIX_V6_LPBIG_OFFBIG LONG_MAX"
.Pp
will display the maximum value of the C type
.Vt long
in the
.Li POSIX_V6_LPBIG_OFFBIG
programming environment,
if the system supports that environment.
.Sh DIAGNOSTICS
Use of a
.Ar system_var
or
.Ar path_var
which is completely unrecognized is considered an error,
causing a diagnostic message to be written to standard error.
One
which is known but merely undefined does not result in an error
indication.
The
.Nm
utility recognizes all of the variables defined for
.St -p1003.1-2001 ,
including those which are not currently implemented.
.Sh SEE ALSO
.Xr pathconf 2 ,
.Xr confstr 3 ,
.Xr sysconf 3
.Sh STANDARDS
The
.Nm
utility is expected to be compliant with
.St -p1003.1-2001 .
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 5.0 .
.Sh AUTHORS
.An Garrett A. Wollman Aq Mt wollman@lcs.mit.edu