gen/confstr.3

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  32 .\"     @(#)confstr.3   8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/gen/confstr.3,v 1.11 2001/10/01 16:08:50 ru Exp $
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  35 .Dd June 18, 2001
  36 .Dt CONFSTR 3
  37 .Os
  38 .Sh NAME
  39 .Nm confstr
  40 .Nd get string-valued configurable variables
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In unistd.h
  45 .Ft size_t
  46 .Fn confstr "int name" "char *buf" "size_t len"
  47 .Sh DESCRIPTION
  48 This interface is specified by
  49 .\" .St -p1003.1-200x .
  50 .Tn POSIX .
  51 A more flexible (but non-portable) interface is provided by
  52 .Xr sysctl 3 .
  53 .Pp
  54 The
  55 .Fn confstr
  56 function provides a method for applications to get configuration
  57 defined string values.
  58 Shell programmers needing access to these parameters should use the
  59 .Xr getconf 1
  60 utility.
  61 .Pp
  62 The
  63 .Fa name
  64 argument specifies the system variable to be queried.
  65 Symbolic constants for each name value are found in the include file
  66 .Aq Pa unistd.h .
  67 The
  68 .Fa len
  69 argument specifies the size of the buffer referenced by the
  70 argument
  71 .Fa buf .
  72 If
  73 .Fa len
  74 is non-zero,
  75 .Fa buf
  76 is a non-null pointer, and
  77 .Fa name
  78 has a value, up to
  79 .Fa len
  80 \- 1 bytes of the value are copied into the buffer
  81 .Fa buf .
  82 The copied value is always null terminated.
  83 .Pp
  84 The available values are as follows:
  85 .Pp
  86 .Bl -tag -width 6n
  87 .Pp
  88 .It Li _CS_PATH
  89 Return a value for the
  90 .Ev PATH
  91 environment variable that finds all the standard utilities.
  92 .El
  93 .Sh RETURN VALUES
  94 If the call to
  95 .Fn confstr
  96 is not successful, 0 is returned and
  97 .Va errno
  98 is set appropriately.
  99 Otherwise, if the variable does not have a configuration defined value,
 100 0 is returned and
 101 .Va errno
 102 is not modified.
 103 Otherwise, the buffer size needed to hold the entire configuration-defined
 104 value is returned.
 105 If this size is greater than the argument
 106 .Fa len ,
 107 the string in
 108 .Fa buf
 109 was truncated.
 110 .Sh ERRORS
 111 The
 112 .Fn confstr
 113 function may fail and set
 114 .Va errno
 115 for any of the errors specified for the library functions
 116 .Xr malloc 3
 117 and
 118 .Xr sysctl 3 .
 119 .Pp
 120 In addition, the following errors may be reported:
 121 .Bl -tag -width Er
 122 .It Bq Er EINVAL
 123 The value of the
 124 .Fa name
 125 argument is invalid.
 126 .El
 127 .Sh LEGACY ERRORS
 128 If the call to
 129 .Fn confstr
 130 is not successful, \-1 (rather than 0) is returned and
 131 .Va errno
 132 is set appropriately.
 133 .Sh SEE ALSO
 134 .Xr getconf 1 ,
 135 .Xr pathconf 2 ,
 136 .Xr sysconf 3 ,
 137 .Xr sysctl 3
 138 .Sh HISTORY
 139 The
 140 .Fn confstr
 141 function first appeared in
 142 .Bx 4.4 .