xref: /freebsd/lib/libc/gen/confstr.3 (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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28.\"	@(#)confstr.3	8.1 (Berkeley) 6/4/93
29.\" $FreeBSD$
30.\"
31.Dd December 3, 2006
32.Dt CONFSTR 3
33.Os
34.Sh NAME
35.Nm confstr
36.Nd get string-valued configurable variables
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In unistd.h
41.Ft size_t
42.Fn confstr "int name" "char *buf" "size_t len"
43.Sh DESCRIPTION
44This interface is specified by
45.St -p1003.1-2001 .
46A more flexible (but non-portable) interface is provided by
47.Xr sysctl 3 .
48.Pp
49The
50.Fn confstr
51function provides a method for applications to get configuration
52defined string values.
53Shell programmers needing access to these parameters should use the
54.Xr getconf 1
55utility.
56.Pp
57The
58.Fa name
59argument specifies the system variable to be queried.
60Symbolic constants for each name value are found in the include file
61.In unistd.h .
62The
63.Fa len
64argument specifies the size of the buffer referenced by the
65argument
66.Fa buf .
67If
68.Fa len
69is non-zero,
70.Fa buf
71is a non-null pointer, and
72.Fa name
73has a value, up to
74.Fa len
75\- 1 bytes of the value are copied into the buffer
76.Fa buf .
77The copied value is always null terminated.
78.Pp
79The available values are as follows:
80.Pp
81.Bl -tag -width 6n
82.Pp
83.It Li _CS_PATH
84Return a value for the
85.Ev PATH
86environment variable that finds all the standard utilities.
87.El
88.Sh RETURN VALUES
89If the call to
90.Fn confstr
91is not successful, 0 is returned and
92.Va errno
93is set appropriately.
94Otherwise, if the variable does not have a configuration defined value,
950 is returned and
96.Va errno
97is not modified.
98Otherwise, the buffer size needed to hold the entire configuration-defined
99value is returned.
100If this size is greater than the argument
101.Fa len ,
102the string in
103.Fa buf
104was truncated.
105.Sh ERRORS
106The
107.Fn confstr
108function may fail and set
109.Va errno
110for any of the errors specified for the library functions
111.Xr malloc 3
112and
113.Xr sysctl 3 .
114.Pp
115In addition, the following errors may be reported:
116.Bl -tag -width Er
117.It Bq Er EINVAL
118The value of the
119.Fa name
120argument is invalid.
121.El
122.Sh SEE ALSO
123.Xr getconf 1 ,
124.Xr pathconf 2 ,
125.Xr sysconf 3 ,
126.Xr sysctl 3
127.Sh HISTORY
128The
129.Fn confstr
130function first appeared in
131.Bx 4.4 .
132