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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.so, libc.a)

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. The standard name value is _CS_PATH.

  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 string value of name,
  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)