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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. 171In the latter case, 172.Va errno 173will be set. 174The functions 175.Fn getgrent_r , 176.Fn getgrnam_r , 177and 178.Fn getgrgid_r 179return 0 if no error occurred, or an error number to indicate failure. 180It is not an error if a matching entry is not found. 181(Thus, if 182.Fa result 183is set to 184.Dv NULL 185and the return value is 0, no matching entry exists.) 186.Pp 187The functions 188.Fn setgroupent 189and 190.Fn setgrent 191return the value 1 if successful, otherwise the value 1920 is returned. 193The functions 194.Fn endgrent 195and 196.Fn setgrfile 197have no return value. 198.Sh FILES 199.Bl -tag -width /etc/group -compact 200.It Pa /etc/group 201group database file 202.El 203.Sh SEE ALSO 204.Xr getpwent 3 , 205.Xr group 5 , 206.Xr nsswitch.conf 5 , 207.Xr yp 8 208.Sh HISTORY 209The functions 210.Fn endgrent , 211.Fn getgrent , 212.Fn getgrnam , 213.Fn getgrgid , 214and 215.Fn setgrent 216appeared in 217.At v7 . 218The functions 219.Fn setgrfile 220and 221.Fn setgroupent 222appeared in 223.Bx 4.3 Reno . 224The functions 225.Fn getgrent_r , 226.Fn getgrnam_r , 227and 228.Fn getgrgid_r 229appeared in 230.Fx 5.1 . 231.Sh STANDARDS 232The 233.Fn getgrent , 234.Fn getgrnam , 235.Fn getgrnam_r , 236.Fn getgrgid , 237.Fn getgrgid_r 238and 239.Fn endgrent 240functions conform to 241.St -p1003.1-96 . 242The 243.Fn setgrent 244function differs from that standard in that its return type is 245.Vt int 246rather than 247.Vt void . 248.Sh COMPATIBILITY 249The historic function 250.Fn setgrfile , 251which allowed the specification of alternate password databases, has 252been deprecated and is no longer available. 253.Sh BUGS 254The functions 255.Fn getgrent , 256.Fn getgrnam , 257.Fn getgrgid , 258.Fn setgroupent 259and 260.Fn setgrent 261leave their results in an internal static object and return 262a pointer to that object. 263Subsequent calls to 264the same function 265will modify the same object. 266.Pp 267The functions 268.Fn getgrent , 269.Fn getgrent_r , 270.Fn endgrent , 271.Fn setgroupent , 272and 273.Fn setgrent 274are fairly useless in a networked environment and should be 275avoided, if possible. 276The 277.Fn getgrent 278and 279.Fn getgrent_r 280functions 281make no attempt to suppress duplicate information if multiple 282sources are specified in 283.Xr nsswitch.conf 5 . 284