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Alphabetical listing for C

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

SYNOPSIS
  #include <unistd.h>

  size_t confstr(
	  int name,
	  char *buf,
	  size_t len );

LIBRARY
  Standard C Library (libc)

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.

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.

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.

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

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

SEE ALSO
  Functions: pathconf(2), sysconf(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for C

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