A Complete Guide to “useradd” Command in Linux with Examples _ Hostbillo

This article will cover how to use the useradd command in Linux to set up new user accounts.

1. ACompleteGuideto“useradd”Commandin
LinuxwithExamples|Hostbillo
Introduction
MultipleuserscaninteractwithLinuxatoncebecauseitisamulti-usersystem.
Youareaccountableforoverseeingthesystem'susersandgroupsbyallowing
anddenyingusersandaddingandremovingthemfromdifferentgroups.
ThisarticlewillcoverhowtousetheuseraddcommandinLinuxtosetup
newuseraccounts.
UseaddCommand
FortheuseraddcommandinLinux,thefollowinggeneralsyntaxapplies:
useradd[OPTIONS]USERNAME

2. Userswithsudobenefitsorrootaretheonlyoneswhocancreatenewuser
accountsinLinuxusingtheuseraddcommand.
Accordingtothechoicesyoutypeatthecommandprompt,theuseradd
commandcreatesanewuseraccountonceyourunit.
Sincethevariablesinthisfilearedifferentbetweendistributions,theLinuxadd
usercommandbehavesdifferentlyonvarioussystems.
Additionally,useraddreadsthedatainthe/etc/login.defsfile.Thisfileincludes
configurationinformationfortheshadowpasswordsuite,includingpassword
expirationpolicy,userIDrangesusedwhencreatingthesystemandregular
users,andmore.
HowtoaddUserinLinux?
Usetheuseraddcommandafterenteringtheuser'snametocreateanewuser
inLinux.
Ifyouwantedtomakeanewuserwiththenameusername,youmightrun:
sudousername

3. Useraddusesthedefaultsettingslistedinthe/etc/default/useraddfilewhenitis
runwithoutanyoptions,creatinganewuseraccount.
Youneedtomarktheaccountpasswordpriortologgingintotherecently
createduserinlinux.Performthepasswdcommand,thenentertheusername:
sudopasswdusername.
Keepinmindtochooseanuniquepassword.
AddaNewUserandCreateaHomeDirectory
MostLinuxdistributionsdonotbuildtheuser'shomedirectorywhenevera
newlyaddedaccountissetupwithuseraddcommand.
Thehomedirectorywouldbecreatedbyimplementingthe-m(—create-home)
element.

4. sudouseradd-musername
Withtheaforementionedcommand,theuser'shomedirectoryiscreatedand
filesfromthe/etc/skeldirectoryarecopiedover.Youcanfindtheinitialization
filesbylistingthefilesinthe/home/usernamedirectory:
ls-la/home/username/
Auser'shomedirectorycancontainfoldersandfilesthattheycanadd,change,
anddelete.
CreateaUserwithSpecificHomeDirectory
UseraddCommandinLinuxinstantlycreatesthehomedirectory.Ifyouwantto
placetheuser'shomedirectorysomewhereelse,thenused(—home)feature.
Usingtheexamplebelow,youcanmakeanewuserwiththenameusername
andahomedirectoryof/opt/username:

5. sudouseradd-m-d/opt/usernameusername
CreateNewUserinLinuxwithSpecificUserId
UsernamesanduniqueUIDsareusedinLinuxandotherUnix-likeoperating
systemstoidentifyusers.
TheLinuxprogramgiveseachuseraspecialpositiveintegerthattheycanrefer
toastheir"useridentifier"(UID).TheUIDaswellasotheraccesscontrol
policiesdefinethetypesofactivitiesauserisallowedtoperformonsystem
resources.
ThesystemwillautomaticallydesignatethefollowingUIDfromthecatalogof
userIDsmentionedinthelogin.defsfiletoanewlycreateduserLinux.
Whenoperatinguseradd,utilise-u(—uid)optiontosetupauserwithanunique
UID.Forinstance,tocreateanewuserwiththeUIDof1700andthename
username,youwouldtype:
sudouseradd-u1700username
Withtheidcommand,youcanconfirmtheuser'sUID:
id-uusername

6. CreateaUserwithaSpecificGroupId
UseraccountsinLinuxareorganizedandmanagedbygroups,whichare
organizationalunits.Themainfunctionofgroupsistospecifyasetofprivileges
thatcanbesharedbyallmembersofthegroup,suchaspermissionsforreading,
writing,orimplementingaspecificresource.
Whenaddinganewuser,theuseraddpromptautomaticallycreatesagroupthat
hastheexactnameastheusernameandtheidenticalGIDastheUID.
Byusing-g(—gid)feature,youcanallocateausertoaspecificinitiallogin
group.YoucanchoosebetweenstatingthegroupnameandtheGIDnumber.
ThegroupIDornamemustalreadybeinuse.
Inthisexample,we'llcreateabrand-newuserwiththenameusername,and
we'llsetthelogingrouptousertype.
sudouseradd-gusersusername
Youcouldperhapsvalidatetheuser'sGIDbyusingidprompt:
id-gnusername

7. AddaUserandallotMultipleGroups
Theterms"primarygroup"aswellas"secondarygroup"refertotwodistinct
categoriesinLinuxoperatingsystems.Eachuserhasamaximumofone
primarygroupandzerotomoresecondarygroupstowhichtheycanbelong.
Withthe-G(—groups)option,youcanspecifyalistofextragroupsthatthe
userwillbelongto.
Withtheprimarygroupusers,secondarygroupswheel,anddocker,the
followingcommandcreatesanewuserwiththenameusername.
sudouseradd-gusers-Gwheel
Additionally,youcouldincorporatesearching
idusername
AddUserinLinuxwithoutanyHomeDirectory
Somesituationscallforustostepawayfromgivingusershomedirectoriesfor
safetypurposes.Inthiscase,theuser'shomedirectorywillberootwhenthey
logintoasystemthathasjustrestarted.Whensuchauserexecutesthesu
command,theprevioususer'shomedirectorywillbeusedasthelogindirectory.
Usingtheoption"-M,"userscanbecreatedwithouthavinghomedirectories.
Youcanmakeauserwithouttheneedforahomedirectorybyusingthe
commandprompt,forexample.

8. sudouseradd-Musername
Thelscommandwillnowbeusedtoconfirmthattheuserwasestablishedwith
noneedforahomedirectory.
sudols-l/home/username
ls:cannotaccess/home/username:Nosuchfileordirectory
AddNewUserwithExpiryDate
Youcandesignateadayandtimeforthenewlyaddedaccounts'expirationby
usingthe-e(—expiredate)feature.Thiscanbeusedtocreatetemporary
accounts.
Inordertospecifyadate,usetheformatYYYY-MM-DD.
Forinstance,tomakeanewuseraccountwiththenameusername(ABC)and
anexpirationdateofApril07th,2023,youwouldexecutethefollowing
command:
sudouseradd-e2023-04-07username(ABC)
Tofindoutwhenanaccountwillexpire,choosethechageprompt:
sudochage-lusername(ABC)

9. CreateNewUserwithCustomComments
Youcanprovideaprecisedescriptionforthenewuserbyusingthe-c
(—comment)option.Usually,acommentwillincludetheuser'sfullnameor
contactinformation.
Intheexamplebelow,weareaddinganewuserwiththenameusernameand
thecommenttextstringTestUserAccount:
sudouseradd-c"TestUserAccount"username
grepusername/etc/passwd
AnothernameforthecommentsectionisGECOS.
AddUserwithachangedloginshell

10. Theloginshellforanewuserisautomaticallysettotheonelistedinthe
/etc/default/useraddfile.Thedefaultshellsettingvariesbetweendistributions;
insome,itis/bin/sh,andinothers,/bin/bash.
Withthe-s(—shell)feature,youcanidentifythenewlyaddeduser'sloginshell.
Forexample,
sudouseradd-s/usr/bin/zshusername
Determinetheuser'sloginshellbyexaminingtheentryinthefile:
grepusername/etc/passwd
ThecommandforChangingtheDefaultuseraddValues
The-D,—defaultsfunction,allowsyoutoseeandmodifythestandarduseradd
configurations.
Toseethecurrentdefaultoptions,usethefollowingsyntax:
useradd-D
Considerthescenariowhereyouwanttoswitchfrom/bin/shto/bin/bashasthe
defaultloginshell.Enterthenewshellinthefollowingformattoachievethat:
sudouseradd-D-s/bin/bash

11. Userscanactuallyconfirmthatthestandardshellcomponenthasbeenaltered
byrunningthecommandshownbelow:
sudouseradd-D|grep-ishell
CommandtosetaPasswordforNewUser
Thefollowingcommandcanbeusedtosetanunencryptedpasswordforthe
user.
sudouseradd-ptest_passwordusername
Thiswillsetupanewuserwiththename"username"andtheunencrypted
password"testpassword".
CommandtoDisplayHelp
Youcandemonstratehelpbyenteringthefollowingsyntax.
sudouseradd--help
Theuseraddcommand'shelpsectionwillbedisplayedwhenthiscommandis
used.

12. Conclusion
We'vedemonstratedinthisarticlehowtousetheuseraddcommandinLinux
toaddnewuseraccounts.AllLinuxdistributions,suchasCentOS,RHEL,
Debian,Ubuntu,andothers,alsoshouldfollowthesameinstructions.Asof
rightnow,youcantestthesefeaturesandattempttogiveLunixmore
functionality.