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30.\"     @(#)scandir.3	8.1 (Berkeley) 6/4/93
31.\"
32.Dd April 29, 2010
33.Dt SCANDIR 3
34.Os
35.Sh NAME
36.Nm scandir ,
37.Nm alphasort
38.Nd scan a directory
39.Sh LIBRARY
40.Lb libc
41.Sh SYNOPSIS
42.In sys/types.h
43.In dirent.h
44.Ft int
45.Fn scandir "const char *dirname" "struct dirent ***namelist" "int \*(lp*select\*(rp\*(lpconst struct dirent *\*(rp" "int \*(lp*compar\*(rp\*(lpconst void *, const void *\*(rp"
46.Ft int
47.Fn alphasort "const void *d1" "const void *d2"
48.Sh DESCRIPTION
49The
50.Fn scandir
51function
52reads the directory
53.Fa dirname
54and builds an array of pointers to directory
55entries using
56.Xr malloc 3 .
57It returns the number of entries in the array.
58A pointer to the array of directory entries is stored in the location
59referenced by
60.Fa namelist .
61.Pp
62The
63.Fa select
64parameter is a pointer to a user supplied subroutine which is called by
65.Fn scandir
66to select which entries are to be included in the array.
67The select routine is passed a
68pointer to a directory entry and should return a non-zero
69value if the directory entry is to be included in the array.
70If
71.Fa select
72is null, then all the directory entries will be included.
73.Pp
74The
75.Fa compar
76parameter is a pointer to a user supplied subroutine which is passed to
77.Xr qsort 3
78to sort the completed array.
79If this pointer is null, the array is not sorted.
80.Pp
81The
82.Fn alphasort
83function
84is a routine which can be used for the
85.Fa compar
86parameter to sort the array alphabetically.
87.Pp
88The memory allocated for the array can be deallocated with
89.Xr free 3 ,
90by freeing each pointer in the array and then the array itself.
91.Sh DIAGNOSTICS
92Returns \-1 if the directory cannot be opened for reading or if
93.Xr malloc 3
94cannot allocate enough memory to hold all the data structures.
95.Sh SEE ALSO
96.Xr directory 3 ,
97.Xr dirent 3 ,
98.Xr malloc 3 ,
99.Xr qsort 3
100.Sh STANDARDS
101The
102.Fn scandir
103and
104.Fn alphasort
105functions conform to
106.St -p1003.1-2008 .
107.Sh HISTORY
108The
109.Fn scandir
110and
111.Fn alphasort
112functions appeared in
113.Bx 4.2 .
114