前言：
在使用bash命令行时，在提示符下输入某个命令的前面几个字符，然后按TAB键，就会列出以这几个字符开头的命令供我们选择。不光如此，还可以进行参数补全，但只限于文件参数，当输入到参数部分时，按TAB键，就会列出以这个参数开头的文件路径供我们选择。 现在http://www.caliban.org/bash/上提供了一个名为bash-completion的软件包，通过一个复杂的脚本bash_completion实现可编程的补全程序，减少系统管理员日常维护工作，减少差错，提高工作效率。
网站：
bash-completion补全工具官网：https://caliban.org/bash/
安装:
在日常管理k8s集群的时候，时刻都会使用到Kubectl命令行工具，但是该命令还是挺复杂的，使用中也记不住那么多的api选项，所以这里介绍一下Kubectl命令补全工具（其实是Linux中bash命令自动补全工具）的安装。
yum -y install bash-completion
source /usr/share/bash-completion/bash_completion
source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc
[root@k8s-master ~]# yum install -y bash-completion ... ... 正在安装 : 1:bash-completion-2.1-8.el7.noarch 1/1 验证中 : 1:bash-completion-2.1-8.el7.noarch 1/1 已安装: bash-completion.noarch 1:2.1-8.el7 完毕！ [root@k8s-master ~]# source /usr/share/bash-completion/bash_completion [root@k8s-master ~]# source <(kubectl completion bash) [root@k8s-master ~]# echo "source <(kubectl completion bash)" >> ~/.bashrc //应用kubectl的completion到系统环境
查看bash_completion补全脚本程序:
[root@k8s-master ~]# vim /usr/share/bash-completion/bash_completion # -*- shell-script -*- # # bash_completion - programmable completion functions for bash 4.1+ # # Copyright © 2006-2008, Ian Macdonald <ian@caliban.org> # © 2009-2013, Bash Completion Maintainers # <bash-completion-devel@lists.alioth.debian.org> # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2, or (at your option) # any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software Foundation, # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. # # The latest version of this software can be obtained here: # # http://bash-completion.alioth.debian.org/ # # RELEASE: 2.1 if [[ $- == *v* ]]; then BASH_COMPLETION_ORIGINAL_V_VALUE="-v" else BASH_COMPLETION_ORIGINAL_V_VALUE="+v" fi if [[ ${BASH_COMPLETION_DEBUG-} ]]; then set -v else set +v fi # Set the following to the location of the backwards compat completion dir. # : ${BASH_COMPLETION_COMPAT_DIR:=/etc/bash_completion.d} readonly BASH_COMPLETION_COMPAT_DIR # Blacklisted completions, causing problems with our code. # _blacklist_glob='@()' # Turn on extended globbing and programmable completion shopt -s extglob progcomp ... ...
验证：
以下自动补全命令验证在不安装bash_completion工具时是无法实现自动补全的。
1.Kubectl命令自动补全：
[root@k8s-master ~]# kube kubeadm kubectl kubelet [root@k8s-master ~]# kubectl --按TAB键两次，提示kubectl后面可跟的命令 annotate certificate debug explain options run wait api-resources cluster-info delete expose patch scale api-versions completion describe get plugin set apply config diff help port-forward taint attach cordon drain kustomize proxy top auth cp edit label replace uncordon autoscale create exec logs rollout version [root@k8s-master ~]# kubectl e edit exec explain expose [root@k8s-master ~]# kubectl exec - --add-dir-header --kubeconfig= --request-timeout --alsologtostderr --log-backtrace-at --request-timeout= --as --log-backtrace-at= -s --as= --log-dir --server --as-group --log-dir= --server= --as-group= --log-file --skip-headers -c --log-file= --skip-log-headers --cache-dir --log-file-max-size --stderrthreshold --cache-dir= --log-file-max-size= --stderrthreshold= --certificate-authority --log-flush-frequency --stdin --certificate-authority= --log-flush-frequency= -t --client-certificate --logtostderr --tls-server-name --client-certificate= --match-server-version --tls-server-name= --client-key -n --token --client-key= --namespace --token= --cluster --namespace= --tty --cluster= --one-output --user --container --password --user= --container= --password= --username --context --pod-running-timeout --username= --context= --pod-running-timeout= -v -f --profile --v --filename --profile= --v= --filename= --profile-output --vmodule -i --profile-output= --vmodule= --insecure-skip-tls-verify -q --warnings-as-errors --kubeconfig --quiet [root@k8s-master ~]# kubectl get n namespaces networkpolicies.networking.k8s.io nodes
2.Linux中bash命令自动补全：
[root@k8s-master ~]# iptables -- --append --flush --line-numbers --numeric --rename-chain --verbose --delete --fragment --list --out-interface --replace --version --delete-chain --in-interface --match --policy --set-counters --zero --destination --insert --modprobe --proto --source --exact --jump --new --protocol --tabl [root@k8s-master ~]# systemctl s set-default set-property show-environment start stop switch-root set-environment show snapshot status suspend [root@k8s-master ~]# firewall-cmd -- --add-forward-port= --list-services --add-icmp-block= --list-source-ports --add-icmp-block-inversion --list-sources --add-interface= --lockdown-off --add-lockdown-whitelist-command= --lockdown-on --add-lockdown-whitelist-context= --panic-off --add-lockdown-whitelist-uid= --panic-on --add-lockdown-whitelist-user= --permanent --add-masquerade --query-forward-port= --add-port= --query-icmp-block= --add-protocol= --query-icmp-block-inversion --add-rich-rule= --query-interface= --add-service= --query-lockdown --add-source= --query-lockdown-whitelist-command= --add-source-port= --query-lockdown-whitelist-context= --change-interface= --query-lockdown-whitelist-uid= --change-source= --query-lockdown-whitelist-user= --change-zone= --query-masquerade --complete-reload --query-panic --direct --query-port= --get-active-zones --query-protocol= --get-default-zone --query-rich-rule= --get-description --query-service= --get-helpers --query-source= --get-icmptypes --query-source-port= --get-ipset-types --reload --get-log-denied --remove-forward-port= --get-services --remove-icmp-block= --get-short --remove-icmp-block-inversion --get-zone-of-interface= --remove-interface= --get-zones --remove-lockdown-whitelist-command= --help --remove-lockdown-whitelist-context= --info-helper= --remove-lockdown-whitelist-uid= --info-icmptype= --remove-lockdown-whitelist-user= --info-ipset= --remove-masquerade --info-service= --remove-port= --info-zone= --remove-protocol= --list-all --remove-rich-rule= --list-all-zones --remove-service= --list-forward-ports --remove-source= --list-icmp-blocks --remove-source-port= --list-interfaces --set-default-zone= --list-lockdown-whitelist-commands --set-description= --list-lockdown-whitelist-contexts --set-log-denied= --list-lockdown-whitelist-uids --set-short= --list-lockdown-whitelist-users --state --list-ports --version --list-protocols --zone= --list-rich-rules
