杂技

cat /etc/shells  说明： 显示 /etc/shells 文件内容，即列出当前系统可用shell

0.0

GNU/bash shell特点

1. 命令和文件自动补齐

2. 命令历史记忆功能上下键、!number、!string、!$、!!、^R

3. 别名功能  alias、unalias cp、~username/.bashrc、\cp -rf /etc/hosts.

4. 快捷键^R、^D、^A、^E、^L、^U、^K、^Y、^S、^Q

5. 前后台作业控制  &、nohup、^C、^Z、bg%1、fg%1、kill %3、screen

6. 输入输出重定向 0,1,2  > >> 2> 2>> 2>&1 &>        cat < /etc/hosts        cat <file1 <

[root@tianyun ~]# ll /dev/std*

lrwxrwxrwx 1 root root 15 Sep  1  2015 /dev/stderr -> /proc/self/fd/2

lrwxrwxrwx 1 root root 15 Sep  1  2015 /dev/stdin -> /proc/self/fd/0

lrwxrwxrwx 1 root root 15 Sep  1  2015 /dev/stdout -> /proc/self/fd/1

7. 管道| tee

ip addr |grep 'inet ' |grep eth0

ip addr |grep 'inet '|tee test|grep eth0覆盖

ip addr |grep 'inet '|tee -a test|grep eth0-a 追加

df |grep '/$'

df|tee df.txt|grep '/$'

[root@tianyun ~]# date > date.txt

[root@tianyun ~]# date |tee date.txt

Fri Aug 25 15:30:20 CST 2017

8. 命令排序

;不具备逻辑判断

cd; eject

&&    ||具备逻辑判断

./configure && make && make install（命令返回值 echo $?）

mkdir /var/111/222/333 && echo ok

mkdir -p /var/111/222/333 && echo ok

ls /home/111/222/333/444 || mkdir -p /home/111/222/333/444

[-d /home/111/222/333/444 ] || mkdir -p /home/111/222/333/444

ping -c1 10.18.42.1 &>/dev/null  && echo up || echo down

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注意：

command &后台执行

command &>/dev/null混合重定向（标准输出1，错误输出2）

command1 && command2命令排序，逻辑判断

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9. shell通配符（元字符）表示的不是本意

*匹配任意多个字符  ls in*  rm -rf *  rm -rf *.pdf  find / -iname "*-eth0"

?匹配任意一个字符  touch love loove live l7ve; ll l?ve

[]匹配括号中任意一个字符 [abc] [a-z] [0-9] [a-zA-Z0-9] [^a-zA-Z0-9]  ll l[io]ve  ll l[^a-z]ve  ll /dev/sd[a-z]

()在子shell中执行(cd /boot;ls)  (umask 077; touch file1000)

{} 集合touch file{1..9}

# mkdir /home/{111,222}mkdir -pv /home/{333/{aaa,bbb},444}

# cp -rv/etc/sysconfig/network-scripts/ifcfg-eth0/etc/sysconfig/network-scripts/ifcfg-eth0.old

# cp -rv/etc/sysconfig/network-scripts/{ifcfg-eth0,ifcfg-eth0.old}

# cp -rv/etc/sysconfig/network-scripts/ifcfg-eth0{,.old}

\转义符，让元字符回归本意

# echo *

# echo\*

# touch yang\sheng

mkdir\\

echo -e "atb"

echo -e "a\tb"

echo -e "anb"

echo -e "a\nb"