Solaris

root@bnesrv50 # getent group | grep -i A
A5:*:2560:a9ad3059,a9an2462,a9ap2447,a9cb2519,a9dm3678,a9es5342,a9jc2364,a9jd3062,a9jl1987,a9lz6481,a9nh4814,a9nm2713,a9rs2507,a9wa2556,ah1901,alastair,at2tha,bryans,c9dg2497,c9fl6347,c9pm2994,c9rc2865,cw2659,dennism,dr2551,eliza,fg2287,ge1700,gkelly,ja2406,jdowling,jkennedy,mf3525,mw2955,petewil,philob,pv2571,rakesh,rg4365,rj2619,rv3526,sl3353,sorcha,t9ar4510,t9ds4473,t9ga4650,t9jg2677,t9kk4511,t9km3147,t9lp4607,t9mt4512,t9ng4556,t9ns4681,t9ra4517,t9rb4551,t9rk4550,t9rs4518,t9rs4519,t9rs4687,t9rv4688,t9sk4509,t9sn4558,t9tk5064,t9tl2850
A:*:2560:a9aa6284,a9ay6972,a9dd3230,a9ek6520,a9is6175,a9mf6529,a9nl6176,a9pw5264,aaronj,alastair,am1603,andreas,andrewhe,angelag,as6984,at2362,at6036,audanoa1,aumaval,awearne,barbara,barryq,billb,bw3825,c9ds5118,c9et2845,c9jk3742,c9lh5683,c9pr9roe,c9rr2844,c9sa4102,c9vt5175,carl,carmeld,chrisw,cm_adm,craigd,danielh,davidh,db5333,dc4340,deborahb,dh7had,dl6218,dt2499,eliza,fa6309,garyg,ggomez,gm5764,gs4912,hw5765,ibligh,ivylee,ja7arj,jasons,jb5706,jennyr,jf1755,jj3191,jl5399,johnmcc,js5694,julianne,jw5241,kassulke,kateoc,kaylee,lc2492,legaultm,lindaw,ls2379,lucy,markh,mc1lis,mehranp,michaelc,mincom,mm4614,mo3756,mp3871,mr4760,mr5705,ms5202,murrayst,na1ain,neilh,norac,otoniel,paul,pd1309,pm2978,pp1609,ps4615,rb4brr,rh5858,rmckenzi,rudi,sc6091,sg3755,sg6200,shonaj,simonam,sl2440,smangrai,speedway,sr4187,ss2125,sscott,t9aa5302,t9ir5065,t9rn6094,tk4638,vasum,wl6264,ws3549
A:*:2560:a9ab4984,a9ad2127,a9ad2789,a9ag1777,a9an3086,a9cd1167,a9dd3185,a9dm1117,a9dm8mcc,a9fb6574,a9ff2276,a9fs1620,a9gd4619,a9gk8kel,a9gp3184,a9hk2804,a9ht5627,a9is6175,a9jr5626,a9kw4985,a9mc1cam,a9nb8bea,a9nl6176,a9rg3061,a9rj2193,a9sc1116,a9sr1765,a9ss4987,a9tl3060,a9ym2814,aa1990,alisonk,bhawson,bradm,brandon,brianm,c9bs4321,c9ew1631,cc8don,ce1925,chansell,ck1971,cmedina,colmo,dt4804,eliza,gm1746,henry,jd1738,jk4176,joe,kathleen,ks1smh,ku2296,lisam,lk1992,maevek,maggiek,marie,mfinney,mlacey,neila,paul1621,paulja,pcaffrey,peterfl,pkeane,pkirk,rossv,rtovar,smythr,sr4943,thayabam,thomasm,tonyha,victor,vu2241,yzarur,z9af3083

root@bnesrv50 # grep cmelusr /etc/group
root@bnesrv50 #

root@bnesrv50 # cat /etc/nsswitch.conf
#
# /etc/nsswitch.dns:
#
# An example file that could be copied over to /etc/nsswitch.conf; it uses
# DNS for hosts lookups, otherwise it does not use any other naming service.
#
# "hosts:" and "services:" in this file are used only if the
# /etc/netconfig file has a "-" for nametoaddr_libs of "inet" transports.

passwd:     files nis
group:      files nis
# You must also set up the /etc/resolv.conf file for DNS name
# server lookup.  See resolv.conf(4).
hosts:      files dns
ipnodes:    files
# Uncomment the following line and comment out the above to resolve
# both IPv4 and IPv6 addresses from the ipnodes databases. Note that
# IPv4 addresses are searched in all of the ipnodes databases before
# searching the hosts databases. Before turning this option on, consult
# the Network Administration Guide for more details on using IPv6.
#ipnodes:      files dns

networks:   files nis
protocols:  files nis
rpc:        files nis
ethers:     files nis
netmasks:   files nis
bootparams: files
publickey:  files
# At present there isn't a 'files' backend for netgroup;  the system will
#   figure it out pretty quickly, and won't use netgroups at all.
netgroup:   files nis
automount:  files nis
aliases:    files
services:   files nis
sendmailvars:   files
printers:       user files
auth_attr:      files
prof_attr:      files
project:    files

root@bnesrv50 # grep A /etc/group
root@bnesrv50 #

getent group | nawk -F: '$3==2560'

ypmatch A group

getent group A