shell示例1

1. 统计出/etc/passwd 文件中默认 shell 为非/sbin/nologin 的用户数,并将用户显示出来

   # 显示用户
   sed -r '/\/sbin\/nologin/d;s#([^:]*).*#\1#' /etc/passwd
   # 显示用户数
   grep -v '/sbin/nologin$' /etc/passwd|wc -l

2. 查出用户 UID 最大值的用户名,UID 和 shell 类型

   sort -rnt ':' -k 3 /etc/passwd|cut -d : -f 1,3,7

3. 统计当前连接本机的每个远程主机 ip 的连接数,并按从大到小排序

   ss -tne|tr -s ' ' ':'|sed '1d'|cut -d ':' -f 6|sort|uniq -c|sort -rn

4. 编写脚本 createuser.sh,实现如下功能
   以一个用户名为参数,如果用户存在,就显示用户存在,否则添加并显示用户 id.

   test $# -lt 1 && echo "No user name" && exit 1
   id $1 &> /dev/null && echo "user $1 is existed,UID is `id -u $1`" && exit 1
   useradd $1
   echo "user is add successed.UID is `id -u $1`"

5. 编写生成脚本基本格式的脚本,包括作者,联系方式,版本,时间,描述等

   #!/bin/bash -e
   # Author: chaoyi
   # Date: 2019-8-31
   # Describe: create a script
   # -------------------------------------------------------------------------------------------------------------------------------------
   
   head_author="# Author:\t\t chaoyiyang"
   head_date="# Date:\t\t\t $(date +%F)"
   head_communication="# Email: [email protected]"
   head_version="# Version: 0.1"
   head_describe="# Describe:"
   head_halving="
   # -------------------------------------------------------------------------------------------------------------------------------------
   "
   
   function create_files
   {
       test $# -lt 1 && echo "Please add file name" && exit 1
       touch $@
       chmod +x $*
   }
   
   function say_success
   {
       echo -e "Success create \033[31m $# \033[0m file."
       time=0
       for i in $@
       do
           printf "%-20s\t" $i
           test $((++time)) -gt 2 && echo && time=0
       done
       echo
       unset i time
   }
   
   # 为不同后缀的文件添加开头
   function add_head
   {
       for i in $@
       do
           case ${i##*.} in
               "sh") echo "#!/bin/bash" > $i ;;
               "py") echo "#!/usr/bin/env python3" > $i ;;
           esac
       done
       unset i
   }
   
   function add_mid
   {
       for i in $@
       do
           echo -e $head_author >> $i
           echo -e $head_date >> $i
           echo -e $head_communication >> $i
           echo -e $head_version >> $i
           echo -e $head_describe >> $i
           echo -e $head_halving >> $i
       done
       unset i
   }
   
   function main
   {
       create_files $@
       add_head $@
       add_mid $@
       say_success $@
   }
   
   main $@