正確使用“useradd”命令

在 Ubuntu 20.04 上，我正在嘗試添加一個使用者，但是它一直失敗。useradd我沒有看到任何錯誤並且對一個簡單的命令感到瘋狂！我究竟做錯了什麼？

root@myhost:~# uname -a
Linux dsdb 5.4.0-109-generic #123-Ubuntu SMP Fri Apr 8 09:10:54 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

root@myhost:~# getent group oinstall
oinstall:x:1001:

root@myhost:~# getent group dba
dba:x:1002:

root@myhost:~# useradd –g oinstall –G dba –m –d /home/oracle oracle
Usage: useradd [options] LOGIN
      useradd -D
      useradd -D [options]

Options:
     --badnames                do not check for bad names
 -b, --base-dir BASE_DIR       base directory for the home directory of the
                               new account
     --btrfs-subvolume-home    use BTRFS subvolume for home directory
 -c, --comment COMMENT         GECOS field of the new account
 -d, --home-dir HOME_DIR       home directory of the new account
 -D, --defaults                print or change default useradd configuration
 -e, --expiredate EXPIRE_DATE  expiration date of the new account
 -f, --inactive INACTIVE       password inactivity period of the new account
 -g, --gid GROUP               name or ID of the primary group of the new
                               account
 -G, --groups GROUPS           list of supplementary groups of the new
                               account
 -h, --help                    display this help message and exit
 -k, --skel SKEL_DIR           use this alternative skeleton directory
 -K, --key KEY=VALUE           override /etc/login.defs defaults
 -l, --no-log-init             do not add the user to the lastlog and
                               faillog databases
 -m, --create-home             create the user's home directory
 -M, --no-create-home          do not create the user's home directory
 -N, --no-user-group           do not create a group with the same name as
                               the user
 -o, --non-unique              allow to create users with duplicate
                               (non-unique) UID
 -p, --password PASSWORD       encrypted password of the new account
 -r, --system                  create a system account
 -R, --root CHROOT_DIR         directory to chroot into
 -P, --prefix PREFIX_DIR       prefix directory where are located the /etc/* files
 -s, --shell SHELL             login shell of the new account
 -u, --uid UID                 user ID of the new account
 -U, --user-group              create a group with the same name as the user
 -Z, --selinux-user SEUSER     use a specific SEUSER for the SELinux user mapping
     --extrausers              Use the extra users database

–在您的命令中不是 ASCII -。在諸如-m工具之類的選項中（幾乎所有工具）都需要普通的舊 ASCII -。

這是您的命令的樣子：

$ printf '%s\n' 'useradd –g oinstall –G dba –m –d /home/oracle oracle' | od -c
0000000   u   s   e   r   a   d   d     342 200 223   g       o   i   n
0000020   s   t   a   l   l     342 200 223   G       d   b   a     342
0000040 200 223   m     342 200 223   d       /   h   o   m   e   /   o
0000060   r   a   c   l   e       o   r   a   c   l   e  \n
0000075

這就是正確命令的樣子：

$ printf '%s\n' 'useradd -g oinstall -G dba -m -d /home/oracle oracle' | od -c
0000000   u   s   e   r   a   d   d       -   g       o   i   n   s   t
0000020   a   l   l       -   G       d   b   a       -   m       -   d
0000040       /   h   o   m   e   /   o   r   a   c   l   e       o   r
0000060   a   c   l   e  \n
0000065

引用自：https://unix.stackexchange.com/questions/701164