一般情况下CentOS7默认最小化安装，此时如果要命令行tab补全需要安装一个叫做“bash-completion” 的软件包
没有安装bash-completion之前
1 [root@localhost ~]# syste 2 anaconda-ks.cfg .bash_logout .bashrc iptables.sh openscap_data/ .tcshrc tools/ 3 .bash_history .bash_profile .cshrc nvidia-bug-report.log.gz .ssh/ test.sh .viminfo 4 [root@localhost ~]# systemctl
安装bash-completion之后
1 [root@localhost ~]# yum install bash-completion 2 Loaded plugins: fastestmirror 3 Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast 4 base | 3.6 kB 00:00:00 5 extras | 3.4 kB 00:00:00 6 updates | 3.4 kB 00:00:00 7 (1/4): base/7/x86_64/group_gz | 166 kB 00:00:00 8 (2/4): extras/7/x86_64/primary_db | 172 kB 00:00:00 9 (3/4): updates/7/x86_64/primary_db | 4.2 MB 00:00:02 10 base/7/x86_64/primary_db FAILED 11 http://mirrors.shu.edu.cn/centos/7.5.1804/os/x86_64/repodata/03d0a660eb33174331aee3e077e11d4c017412d761b7f2eaa8555e7898e701e0-primary.sqlite.bz2: [Errno 14] curl#7 - "Failed connect to mirrors.shu.edu.cn:80; Connection refused" ETA 12 Trying other mirror. 13 (4/4): base/7/x86_64/primary_db | 5.9 MB 00:00:01 14 Determining fastest mirrors 15 * base: mirrors.cn99.com 16 * extras: mirrors.cn99.com 17 * updates: mirrors.cn99.com 18 Resolving Dependencies 19 --> Running transaction check 20 ---> Package bash-completion.noarch 1:2.1-6.el7 will be installed 21 --> Finished Dependency Resolution 22 23 Dependencies Resolved 24 25 ======================================================================================================================================================================================================================================== 26 Package Arch Version Repository Size 27 ======================================================================================================================================================================================================================================== 28 Installing: 29 bash-completion noarch 1:2.1-6.el7 base 85 k 30 31 Transaction Summary 32 ======================================================================================================================================================================================================================================== 33 Install 1 Package 34 35 Total download size: 85 k 36 Installed size: 259 k 37 Is this ok [y/d/N]: y 38 Downloading packages: 39 bash-completion-2.1-6.el7.noarch.rpm | 85 kB 00:00:00 40 Running transaction check 41 Running transaction test 42 Transaction test succeeded 43 Running transaction 44 Installing : 1:bash-completion-2.1-6.el7.noarch 1/1 45 Verifying : 1:bash-completion-2.1-6.el7.noarch 1/1 46 47 Installed: 48 bash-completion.noarch 1:2.1-6.el7 49 50 Complete! 51 [root@localhost ~]#
再次执行systemctl命令
1 [root@localhost ~]# system 2 systemctl systemd-cgls systemd-detect-virt systemd-inhibit systemd-nspawn systemd-sysv-convert 3 systemd-analyze systemd-cgtop systemd-escape systemd-loginctl systemd-path systemd-tmpfiles 4 systemd-ask-password systemd-coredumpctl systemd-firstboot systemd-machine-id-setup systemd-run systemd-tty-ask-password-agent 5 systemd-cat systemd-delta systemd-hwdb systemd-notify systemd-stdio-bridge 6 [root@localhost ~]# system
显示以system开头的所有命令