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Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" From: @(#)getgrent.3 8.2 (Berkeley) 4/19/94 33.\" $FreeBSD$ 34.\" 35.Dd April 16, 2003 36.Dt GETGRENT 3 37.Os 38.Sh NAME 39.Nm getgrent , 40.Nm getgrent_r , 41.Nm getgrnam , 42.Nm getgrnam_r , 43.Nm getgrgid , 44.Nm getgrgid_r , 45.Nm setgroupent , 46.Nm setgrent , 47.Nm endgrent 48.Nd group database operations 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In grp.h 53.Ft struct group * 54.Fn getgrent void 55.Ft int 56.Fn getgrent_r "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" 57.Ft struct group * 58.Fn getgrnam "const char *name" 59.Ft int 60.Fn getgrnam_r "const char *name" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" 61.Ft struct group * 62.Fn getgrgid "gid_t gid" 63.Ft int 64.Fn getgrgid_r "gid_t gid" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" 65.Ft int 66.Fn setgroupent "int stayopen" 67.Ft int 68.Fn setgrent void 69.Ft void 70.Fn endgrent void 71.Sh DESCRIPTION 72These functions operate on the group database file 73.Pa /etc/group 74which is described 75in 76.Xr group 5 . 77Each line of the database is defined by the structure 78.Vt group 79found in the include 80file 81.In grp.h : 82.Bd -literal -offset indent 83struct group { 84 char *gr_name; /* group name */ 85 char *gr_passwd; /* group password */ 86 gid_t gr_gid; /* group id */ 87 char **gr_mem; /* group members */ 88}; 89.Ed 90.Pp 91The functions 92.Fn getgrnam 93and 94.Fn getgrgid 95search the group database for the given group name pointed to by 96.Fa name 97or the group id pointed to by 98.Fa gid , 99respectively, returning the first one encountered. Identical group 100names or group gids may result in undefined behavior. 101.Pp 102The 103.Fn getgrent 104function 105sequentially reads the group database and is intended for programs 106that wish to step through the complete list of groups. 107.Pp 108The functions 109.Fn getgrent_r , 110.Fn getgrnam_r , 111and 112.Fn getgrgid_r 113are thread-safe versions of 114.Fn getgrent , 115.Fn getgrnam , 116and 117.Fn getgrgid , 118respectively. 119The caller must provide storage for the results of the search in 120the 121.Fa grp , 122.Fa buffer , 123.Fa bufsize , 124and 125.Fa result 126arguments. 127When these functions are successful, the 128.Fa grp 129argument will be filled-in, and a pointer to that argument will be 130stored in 131.Fa result . 132If an entry is not found or an error occurs, 133.Fa result 134will be set to 135.Dv NULL . 136.Pp 137These functions will open the group file for reading, if necessary. 138.Pp 139The 140.Fn setgroupent 141function 142opens the file, or rewinds it if it is already open. If 143.Fa stayopen 144is non-zero, file descriptors are left open, significantly speeding 145functions subsequent calls. This functionality is unnecessary for 146.Fn getgrent 147as it doesn't close its file descriptors by default. It should also 148be noted that it is dangerous for long-running programs to use this 149functionality as the group file may be updated. 150.Pp 151The 152.Fn setgrent 153function 154is identical to 155.Fn setgroupent 156with an argument of zero. 157.Pp 158The 159.Fn endgrent 160function 161closes any open files. 162.Sh RETURN VALUES 163The functions 164.Fn getgrent , 165.Fn getgrnam , 166and 167.Fn getgrgid , 168return a pointer to a group structure on success or 169.Dv NULL 170if the entry is not found or if an error occurs. 171If an error does occur, 172.Va errno 173will be set. 174Note that programs must explicitly set 175.Va errno 176to zero before calling any of these functions if they need to 177distinguish between a non-existent entry and an error. 178The functions 179.Fn getgrent_r , 180.Fn getgrnam_r , 181and 182.Fn getgrgid_r 183return 0 if no error occurred, or an error number to indicate failure. 184It is not an error if a matching entry is not found. 185(Thus, if 186.Fa result 187is set to 188.Dv NULL 189and the return value is 0, no matching entry exists.) 190.Pp 191The functions 192.Fn setgroupent 193and 194.Fn setgrent 195return the value 1 if successful, otherwise the value 1960 is returned. 197The functions 198.Fn endgrent 199and 200.Fn setgrfile 201have no return value. 202.Sh FILES 203.Bl -tag -width /etc/group -compact 204.It Pa /etc/group 205group database file 206.El 207.Sh SEE ALSO 208.Xr getpwent 3 , 209.Xr group 5 , 210.Xr nsswitch.conf 5 , 211.Xr yp 8 212.Sh HISTORY 213The functions 214.Fn endgrent , 215.Fn getgrent , 216.Fn getgrnam , 217.Fn getgrgid , 218and 219.Fn setgrent 220appeared in 221.At v7 . 222The functions 223.Fn setgrfile 224and 225.Fn setgroupent 226appeared in 227.Bx 4.3 Reno . 228The functions 229.Fn getgrent_r , 230.Fn getgrnam_r , 231and 232.Fn getgrgid_r 233appeared in 234.Fx 5.1 . 235.Sh STANDARDS 236The 237.Fn getgrent , 238.Fn getgrnam , 239.Fn getgrnam_r , 240.Fn getgrgid , 241.Fn getgrgid_r 242and 243.Fn endgrent 244functions conform to 245.St -p1003.1-96 . 246The 247.Fn setgrent 248function differs from that standard in that its return type is 249.Vt int 250rather than 251.Vt void . 252.Sh COMPATIBILITY 253The historic function 254.Fn setgrfile , 255which allowed the specification of alternate password databases, has 256been deprecated and is no longer available. 257.Sh BUGS 258The functions 259.Fn getgrent , 260.Fn getgrnam , 261.Fn getgrgid , 262.Fn setgroupent 263and 264.Fn setgrent 265leave their results in an internal static object and return 266a pointer to that object. 267Subsequent calls to 268the same function 269will modify the same object. 270.Pp 271The functions 272.Fn getgrent , 273.Fn getgrent_r , 274.Fn endgrent , 275.Fn setgroupent , 276and 277.Fn setgrent 278are fairly useless in a networked environment and should be 279avoided, if possible. 280The 281.Fn getgrent 282and 283.Fn getgrent_r 284functions 285make no attempt to suppress duplicate information if multiple 286sources are specified in 287.Xr nsswitch.conf 5 . 288