笔记

[dmtsai@study ~]$ declare [- - aixr] variable
选项与参数：
-a ：将后面名为 variable 的变量定义成为数组 (array) 类型
-i ：将后面名为 variable 的变量定义成为整数数字 (integer) 类型
-x ：用法与 export 一样，就是将后面的 variable 变成环境变量；
-r ：将变量设定成为 readonly 类型，该变量不可被更改内容，也不能 unset

declare -x sum 将 sum 变成环境变量
-r sum 变成只读属性，不可改动
+x sum 变成非环境变量的自定义变量

[dmtsai@study ~]$ var[1]="s mall min"
[dmtsai@study ~]$ var[2]="big min"
[dmtsai@study ~]$ var[3]="nice min"
[dmtsai@study ~]$ echo "${var[1]}, ${var[2]}, ${var[3]}"
small min, big min, nice min

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#echo $PATH

echo显示字符串（指定环境变量），PATH系统路径。如下图：

 

#alias rm='rm -r' 设置命令别名
#unalias rm 解除命令别名
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| history | 查看命令行历史
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stty -a 来列出目前环境中所有的按键列表|
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[dmtsai@study ~]$ cat > catfile 利用 cat 指令来建立一个文件的简单流程
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testing
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cat file test
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[dmtsai@study ~]$ cat catfile
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testing
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cat file test
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cut -
-d ：后面接分隔字符。与 -f 一起使用；
-f ：依据 -d 的分隔字符将一段讯息分区成为数段，用 -f 取出第几段的意思；
-c ：以字符 (characters) 的单位取出固定字符区间；

[ming@pxe150 ~]$ echo ${PATH}
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/usr/lib64/qt-3.3/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/ming/bin
1| 2| 3| 4| 5| 6| 7|
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[ming@pxe150 ~]$ echo ${PATH} | cut -d ':' -f 4 单引号里显示要切出的为： -f 4为切出第4个
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/usr/bin 我们是以『 : 』作为分隔，因此会出现 /usr/bin 单引号里必须是一个字符
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[ming@pxe150 ~]$ echo ${PATH} | cut -d ':' -f 3
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/bin
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[ming@pxe150 ~]$ echo ${PATH} | cut -d ':' -f 1
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/usr/lib64/qt-3.3/bin
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[dmtsai@study ~]$ export | cut - c 12-
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|必须是命令|
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[root@pxe150 ~]# gedit /etc/centos-release 更改虚拟机版本号
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[root@pxe150 ~]# lsb_release -a 查看版本号
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lscpu 查看cpu
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[root@pxe150 ~]# uname -r 查看版本号
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2.6.32-504.el6.x86_64
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[root@pxe150 ~]# hostname 显示完整的主机名
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localhost.localdomain
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# basename /etc/sysconfig/ 取出文件名
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sysconfig
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# basename /etc/sysconfig/ming/bins/asas/ 取出文件名
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asas
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# dirname /etc/sysconfig/ 取出目录名
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sysconfig
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# dirname /etc/sysconfig/ming/bing/asas/ 取出目录名
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/etc/sysconfig/ming/bing
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# enable -n echo 禁用内部命令echo
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# enable -n cd 禁用内部命令cd
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# type echo 查看是内部命令还是外部命令
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echo is a shell builtin 回声shell内置命令 builtin 内置命令
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# type cd 查看是内部命令还是外部命令
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cd is a shell builtin cd是一个shell内置命令
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# enable echo 启用echo命令
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# enable cd 启用cd命令
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[root@localhost ~]# hash 显示hash缓存
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hits command
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1 /bin/grep
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[root@localhost ~]# hash -d grep 清除grep 缓存
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[root@localhost ~]# hash 显示hash缓存
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hash: hash table empty 清除后
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# hash -l 显示hash缓存，可做输出使用
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# hash -p path name 将命令全路径path起别名为name
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# hash -t name 打印缓存中name的路径
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# hash -r 清除缓存
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hwclock clock 显示硬件时钟
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hwclock -s --hctosys 以硬件时钟为准，校正系统时钟
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hwclock -w --systohc 以系统时钟为准，校正硬件时钟
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关机：halt, poweroff 重启：reboot -f: 强制，不调用shutdown -p: 切断电源
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v 用户登录信息查看命令：
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# whoami: 显示当前登录有效用户 # who: 系统当前所有的登录会话 # w: 系统当前所有的登录会话及所做的操作
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# echo -e "\a" 发出警告声
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[root@localhost ~]# echo -e "abcdd\befg" 退格键 \b
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abcdefg
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[root@localhost ~]# echo -e 'ab\n' 换行 \n
ab

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[root@localhost ~]# echo -e "abc\refgp" 回车，即光标移至行首，但不换行
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efgp
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[root@localhost ~]# echo -e "abcdd\refg" 回车，即光标移至行首，但不换行
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efgdd
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[root@localhost ~]# echo -e 'ab\tcdf' 插入tab
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ab cdf
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[root@localhost ~]# echo -e 'ab\tcdf\tbbb' 插入tab
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ad cdf bbb
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[root@localhost ~]# echo -e "ab\\" 插入\
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ab\
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[root@localhost ~]# bc
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obase=8 8进制
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[root@localhost ~]# > asd 创建文件asd，如果文件asd存在则把asd清空，覆盖原有文件时间戳改变
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[root@localhost ~]# >> asd 创建文件asd，如果文件asd存在不会把asd文件清空，时间戳也不会改变
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[root@localhost ~]# vim lks 创建文件lks
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[root@localhost ~]# ll !* !*显示上一个命令执行的文件lks
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[root@localhost ~]# mkdir mksd aslfk 创建目录
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[root@localhost ~]# ^mkdir^ll 使用ll替换上一个命令 上一个命令需要^^把mkdir包起来
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ll mksd aslfk
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aslfk:
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总用量 0
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[root@study ~]# cp cp 的用法 常用
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-a ：相当于 -dr --preserve=all 的意思，至于 dr 请参考下列说明；(常用)
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-i ：若目标文件(destination)已经存在时，在覆盖时会先询问动作的进行(常用)
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-p ：连同文件的属性(权限、用户、时间)一起复制过去，而非使用默认属性(备份常用)；
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-r ：递归持续复制，用于目录的复制行为；(常用)
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[root@localhost ~]# ls /root/.* 显示root目录下隐藏文件
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[root@localhost ~]# ls --ignore="[^.].*"显示root目录下隐藏文件
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[root@localhost ~]# ls -d .* 显示root目录下隐藏文件
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[root@localhost ~]# ls .* 显示root目录下隐藏文件
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[root@localhost ~]# ls -d /ect/*/ 显示ect目录下非隐藏文件
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^ 托字符表示非 否 忽略
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reset 进入一个全新的环境中||||||||||||||||||||||||||||||||||||||||||||||
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[root@localhost ~]# > 123 清空文件123