group配置文件及groupadd指令帮助手册

Ubuntu Server2204用户组管理groupadd指令帮助手册如下。

1、查看group配置文件帮助手册

GROUP(5)                                       Linux Programmer's Manual                                      GROUP(5)NAME       group - user group fileDESCRIPTION       The  /etc/group  file  is a text file that defines the groups on the system.  There is one entry per line, with       the following format:           group_name:password:GID:user_list       The fields are as follows:       group_name              the name of the group.       password              the (encrypted) group password.  If this field is empty, no password is needed.       GID    the numeric group ID.       user_list              a list of the usernames that are members of this group, separated by commas.FILES       /etc/groupBUGS       As the 4.2BSD initgroups(3) man page says: no one seems to keep /etc/group up-to-date.SEE ALSO       chgrp(1), gpasswd(1), groups(1), login(1), newgrp(1), sg(1), getgrent(3), getgrnam(3),  gshadow(5),  passwd(5),       vigr(8)COLOPHON       This  page  is  part of release 5.10 of the Linux man-pages project.  A description of the project, information       about   reporting   bugs,    and    the    latest    version    of    this    page,    can    be    found    at                                                        2020-04-11                                              GROUP(5)

2、groupadd指令的帮助手册如下

GROUPADD(8)                                   System Management Commands                                   GROUPADD(8)NAME       groupadd - create a new groupSYNOPSIS       groupadd [options] groupDESCRIPTION       The groupadd command creates a new group account using the values specified on the command line plus the       default values from the system. The new group will be entered into the system files as needed.OPTIONS       The options which apply to the groupadd command are:       -f, --force           This option causes the command to simply exit with success status if the specified group already exists.           When used with -g, and the specified GID already exists, another (unique) GID is chosen (i.e.  -g is turned           off).       -g, --gid GID           The numerical value of the group's ID. This value must be unique, unless the -o option is used. The value           must be non-negative. The default is to use the smallest ID value greater than or equal to GID_MIN and           greater than every other group.           See also the -r option and the GID_MAX description.       -h, --help           Display help message and exit.       -K, --key KEY=VALUE           Overrides /etc/login.defs defaults (GID_MIN, GID_MAX and others). Multiple -K options can be specified.           Example: -K GID_MIN=100  -K GID_MAX=499           Note: -K GID_MIN=10,GID_MAX=499 doesn't work yet.       -o, --non-unique           This option permits to add a group with a non-unique GID.       -p, --password PASSWORD           The encrypted password, as returned by crypt(3). The default is to disable the password.           Note: This option is not recommended because the password (or encrypted password) will be visible by users           listing the processes.           You should make sure the password respects the system's password policy.       -r, --system           Create a system group.           The numeric identifiers of new system groups are chosen in the SYS_GID_MIN-SYS_GID_MAX range, defined in           login.defs, instead of GID_MIN-GID_MAX.       -R, --root CHROOT_DIR           Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.       -P, --prefix PREFIX_DIR           Apply changes in the PREFIX_DIR directory and use the configuration files from the PREFIX_DIR directory.           This option does not chroot and is intended for preparing a cross-compilation target. Some limitations: NIS           and LDAP users/groups are not verified. PAM authentication is using the host files. No SELINUX support.CONFIGURATION       The following configuration variables in /etc/login.defs change the behavior of this tool:       GID_MAX (number), GID_MIN (number)           Range of group IDs used for the creation of regular groups by useradd, groupadd, or newusers.           The default value for GID_MIN (resp.  GID_MAX) is 1000 (resp. 60000).       MAX_MEMBERS_PER_GROUP (number)           Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in           /etc/group (with the same name, same password, and same GID).           The default value is 0, meaning that there are no limits in the number of members in a group.           This feature (split group) permits to limit the length of lines in the group file. This is useful to make           sure that lines for NIS groups are not larger than 1024 characters.           If you need to enforce such limit, you can use 25.           Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use           this variable unless you really need it.       SYS_GID_MAX (number), SYS_GID_MIN (number)           Range of group IDs used for the creation of system groups by useradd, groupadd, or newusers.           The default value for SYS_GID_MIN (resp.  SYS_GID_MAX) is 101 (resp.  GID_MIN-1).FILES       /etc/group           Group account information.       /etc/gshadow           Secure group account information.       /etc/login.defs           Shadow password suite configuration.CAVEATS       It is usually recommended to only use groupnames that begin with a lower case letter or an underscore, followed       by lower case letters, digits, underscores, or dashes. They can end with a dollar sign. In regular expression       terms: [a-z_][a-z0-9_-]*[$]?       On Debian, the only constraints are that groupnames must neither start with a dash ('-') nor plus ('+') nor       tilde ('~') nor contain a colon (':'), a comma (','), or a whitespace (space:' ', end of line: '\n',       tabulation: '\t', etc.).       On Ubuntu, the same constraints as Debian are in place, with the additional constraint that the groupname       cannot be fully numeric. This includes octal and hexadecimal syntax.       Groupnames may only be up to 32 characters long.       You may not add a NIS or LDAP group. This must be performed on the corresponding server.       If the groupname already exists in an external group database such as NIS or LDAP, groupadd will deny the group       creation request.EXIT VALUES       The groupadd command exits with the following values:       0           success       2           invalid command syntax       3           invalid argument to option       4           GID not unique (when -o not used)       9           group name not unique       10           can't update group fileSEE ALSO       chfn(1), chsh(1), passwd(1), gpasswd(8), groupdel(8), groupmod(8), login.defs(5), useradd(8), userdel(8),       usermod(8).shadow-utils 4.8.1                                    03/14/2022                                           GROUPADD(8)

时不时研读下官方帮助手册，对整个语感的培养，以及搜索更为专业的知识是进阶的基本能力了，加油。