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Alphabetical listing for C

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confstr(3)
NAME
  confstr - Determines the current value of a specified system variable
  defined by a string value

LIBRARY
  Standard C Library (libc)

SYNOPSIS
  #include <unistd.h>
  size_t confstr(
	  int name,
	  char *buf,
	  size_t len);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  confstr():  XPG4, XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  name Specifies the system variable setting to be returned. Valid values for
       the name parameter are defined in the unistd.h header file:

       _CS_PATH
	    Copies a value for the PATH environment variable that finds all
	    standard utilities into the buffer.

       _CS_PRODUCT_NAME
	    [Tru64 UNIX]  Copies the official name of the installed operating
	    system product into the buffer.

       _CS_SYSTEM_BANNER
	    [Tru64 UNIX]  Copies the official system banner into the buffer.
	    The banner typically consists of the vendor name followed by the
	    product name.

       _CS_SYSTEM_VERSION
	    [Tru64 UNIX]  Copies the product version information into the
	    buffer.

       _CS_VENDOR_ABBREV
	    [Tru64 UNIX]    Copies the official abbreviated company name of
	    the operating system manufacturer into the buffer. If the
	    abbreviated name was not specified, copies the full company name
	    (same as _CS_VENDOR_NAME).

       _CS_VENDOR_NAME
	    [Tru64 UNIX]  Copies the official company name of the operating
	    system manufacturer into the buffer.

       _CS_XBS5_ILP32_OFF32_id

       _CS_XBS5_ILP32_OFFBIG_id

       _CS_XBS5_ILP64_OFF64_id

       _CS_XBS5_LPBIG_OFFBIG_id
	    Specifies values to be passed to utilities used in building an
	    application. The name of the parameter establishes type-size
	    constraints for the environment in which an application is being
	    built:

	    _CS_XBS5_ILP32_OFF32_id
		 The int, long, pointer, and off_t types are treated as 32-
		 bit types.

	    _CS_XBS5_ILP32_OFFBIG_id
		 The int, long, and pointer types are treated as 32-bit
		 types, and the off_t type is treated as a type with at least
		 64 bits.

	    _CS_XBS5_LP64_OFF64_id
		 The int type is treated as a 32-bit type, and the long,
		 pointer, and off_t types are treated as 64-bit types.

	    _CS_XBS5_LPBIG_OFFBIG_id
		 The int type is treated as a type with at least 32 bits, and
		 the long, pointer, and off_t types are treated as types with
		 at least 64 bits.

	    The parameter suffix (id) identifies the component affected by
	    the type-size constraint:

	    CFLAGS
		 The value of the parameter is the set of initial options
		 (compilation options) to be given to cc or c89.

	    LDFLAGS
		 The value of the parameter is the set of final options
		 (loader options) to be given to cc or c89.

	    LIBS The value of the parameter is the set of libraries to be
		 given to cc or c89.

	    LINT The value of the parameter is the set of checking options to
		 be given to lint.

	    In all cases, if

	    sysconf (_SC_XBS5_ILP32_OFFBIG)

	    returns -1, the meaning of the passed values is unspecified.

  buf  Points to the buffer into which the confstr function copies the name
       value.

  len  Specifies the size of the buffer storing the name value.

DESCRIPTION
  The confstr() function allows an application to determine the current
  setting of certain system parameters, limits, or options that are defined
  by a string value. The function is mainly used by applications to find the
  system default value for the PATH environment variable.

  If the following conditions are true, then the confstr() function copies
  that value into a len-byte buffer pointed to by the buf parameter:

    ·  The len parameter is not 0 (zero)

    ·  The name parameter has a system-defined value

    ·  The buf parameter is not a null pointer

  If the string to be returned is longer than len bytes, including the
  terminating null, then the confstr() function truncates the string to len-1
  bytes and adds a terminating null to the result. The application can detect
  that the string was truncated by comparing the value returned by confstr()
  with the value of len.

  If the value of the len parameter is set to 0 (zero) or the buf value is
  NULL, the confstr() function returns the size of the buffer needed to hold
  the entire system-defined value, but does not copy the string value.

EXAMPLES
  To find out how big a buffer is needed to store the _CS_PATH string value,
  enter:

       confstr(_CS_PATH, NULL, (size_t) 0)

  The confstr() function returns the size of the buffer necessary.

RETURN VALUES
  If the value specified by the name parameter is system-defined, the
  confstr() function returns the size of the buffer needed to hold the entire
  value. If this return value is greater than the specified len value, the
  string returned as the buf value is truncated.

  If the specified name value is invalid, a value of 0 (zero) is returned,
  and the errno global variable is set to indicate the error.

  If the specified name value does not have a system-defined value, the
  confstr() function returns a value of 0 (zero) and leaves errno unchanged.

ERRORS
  The confstr() function sets errno as follows:

  [EINVAL]
       The value of the name parameter is invalid.

FILES
  /usr/include/limits.h
       Contains system-defined limits.

  /usr/include/unistd.h
       Contains system-defined environment variables.

RELATED INFORMATION
  Functions: pathconf(2), sysconf(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for C

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