Shell脚本攻略读书笔记之六
查看时区 date -R
更改时区 tzselect
查看时间 date
查看日历 cal
修改时间 date -s
- 11/28/2016【接日期】 将时间修改为2016年11月28日0点
- 0:16:11【接时间】 修改当前时间为 0:16:11
[root@server4 local]# date -s 11/11/2020
Wed Nov 11 00:00:00 CST 2020
[root@server4 local]# date -s 0:16:12
Wed Nov 11 00:16:12 CST 2020centos 7修改时区【这个可能与在系统初始化时有关】
[root@server4 local]# date
Sat Jul 7 04:51:47 EDT 2018
[root@server4 local]# ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
[root@server4 local]# date
Sat Jul 7 16:54:18 CST 2018
[root@server3 cm]#
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place (makes backup if SUFFIX supplied)
1.软连接的问题
3.重要的参数
netstat -a | grep 6000
associative arrays:关联数组。关联数组借用的是散列（hash）函数。
Initially,a declaration statement is required to declare a variable name as an associative array. This can be done as follows:
declare -A ass_array
[root@server4 ~]# alias hello = 'echo hello'
-bash: alias: hello: not found
-bash: alias: =: not found
-bash: alias: echo hello: not found
[root@server4 ~]# alias hello='echo hello'
[root@server4 ~]# hello
hello
[root@server4 ~]# hello
hello
[root@server4 ~]# hi
bash: hi: command not found...
为什么我定义成如下的样子，却跑不出来：alias rm='cp $@ ~/backup && rm $@'
See how to indentify them.
The attacker might have aliased the privileged command with his/her own custom command to steal the critical information that is provided by the user to the command.
alias命令
The -echo option in the preceding command disables the output to the terminal, whereas echo enables output.
选项-echo禁止将输出发送到终端，而选项echo则允许发送输出。
[root@server4 ~]# ./test4.sh
Enter password:
The password your input is 123456
[root@server4 ~]#
echo
-e参数：enable interpretation of backslash escapes【支持使用转义字符】
-n参数：do not output the trailing newline【不输出换行】
backslash：反斜杠
date: %s seconds since 1970-01-01 00:00:00 UTC
用tput sc存储光标的位置。
在每次循环中，我们通过恢复之前存储的光标位置，在终端中打印出新的count值。
tput rc：恢复光标位置
tput ed清除从当前光标位置到行尾之间的所有内容。
set -x表示调试开始
set +x表示调试结束
aforementioned:上述的
Shebang hack
The shebang can be changed from #!/bin/bash to #!/bin/bash -xv to enable
debugging without any additional flags (-xv flags themselves).
这句话的意思是，如果脚本开头是#!/bin/bash，那么当我们想要调试时，我们需要使用-xv这个参数。但是当脚本开头是#!/bin/bash -xv开头时，就可以直接开启debug模式了。
[root@server4 ~]# mkdir backup
[root@server4 ~]# ll
total 1
drwxr-xr-x. 2 root root 6 Jul 25 18:55 backup
做删除
[root@server4 ~]# alias rm='cp $@ ~/backup && rm $@'
[root@server4 ~]# rm -rf out.txt
cp: missing destination file operand after ‘/root/backup’
Try 'cp --help' for more information.
[root@server4 ~]# cd backup/
[root@server4 backup]# pwd
/root/backup
[root@server4 backup]# rm out.txt
cp: missing destination file operand after ‘/root/backup’
Try 'cp --help' for more information.
[root@server4 ~]# alias copy='cp $@ ~/backup'
[root@server4 ~]# ll
total 140284
-rw-r--r--. 1 root root 92 Jul 13 16:46 1
-rwxr-xr-x. 1 root root 339 Jul 17 13:54 addScalaHome.sh
-rwxr-xr-x. 1 root root 377 Jul 11 20:58 adjustSysctlConf.sh
-rw-------. 1 root root 1260 Jun 16 01:12 anaconda-ks.cfg
drwxr-xr-x. 2 root root 6 Jul 25 18:55 backup
-rw-r--r--. 1 root root 9 Jul 20 21:02 cal
-rwxr-xr-x. 1 root root 99 Jul 20 20:39 checkUser.sh
-rwxr-xr-x. 1 root root 115 Jul 13 17:00 checkZookeeper.sh
-rwxr-xr-x. 1 root root 155 Jul 22 17:20 closeZookeeper.sh
drwxr-xr-x. 4 root root 37 Jul 13 11:01 hadoop_temp
-rw-r--r--. 1 root root 54 Jul 4 14:11 HelloLinux.txt
-rw-r--r--. 1 root root 42 Jul 22 20:56 hosts
-rwxr-xr-x. 1 root root 93 Jul 13 17:16 jps.sh
-rw-r--r--. 1 root root 67 Jul 25 11:24 log.txt
-rw-r--r--. 1 root root 78066230 Jul 13 17:36 opentsdb-2.3.0.tar.gz
drwxr-xr-x. 3 root root 8192 Jul 22 16:21 openTSDB_temp
-rw-r--r--. 1 root root 15 Jul 25 14:22 output.txt
-rw-r--r--. 1 root root 216 Jul 23 22:00 out.txt
-rwxr-xr-x. 1 root root 71 Jul 22 16:56 reboot.sh
-rw-r--r--. 1 root root 28678231 Mar 4 2016 scala-2.11.8.tgz
-rwxr-xr-x. 1 root root 267 Jul 13 17:01 startZookeeper.sh
-rw-r--r--. 1 root root 58 Jul 23 09:43 stderr.txt
-rw-r--r--. 1 root root 0 Jul 23 09:43 stdout.txt
-rw-r--r--. 1 root root 3497 Jul 20 19:19 temp
-rwxr-xr-x. 1 root root 138 Jul 20 14:40 test2.sh
-rwxr-xr-x. 1 root root 102 Jul 25 11:22 test3.sh
-rwxr-xr-x. 1 root root 98 Jul 20 14:41 test.sh
-rw-r--r--. 1 root root 3454 Jul 22 21:05 test.zip
-rw-r--r--. 1 root root 36670230 Jul 7 15:36 zookeeper-3.4.11.tar.gz
-rw-r--r--. 1 root root 124241 Jul 22 20:55 zookeeper.out
[root@server4 ~]# copy stdout.txt
cp: omitting directory ‘/root/backup’
[root@server4 ~]# hello
[root@server4 ~]#
[root@server4 ~]# tput cols
[root@server4 ~]#
[root@server4 ~]# tput lines
[root@server4 ~]#
[root@server4 ~]# tput lines
[root@server4 ~]#
[root@server4 ~]# tput cols
[root@server4 ~]#
[root@server4 ~]# tput logname
[root@server4 ~]# info capability 'logname'
[root@server4 ~]# tput longname
[root@server4 ~]# lator (X Window System)[root@server4 ~]#
[root@server4 ~]#
[root@server4 ~]# tput cup 100 100
[root@server4 ~]# [
[root@server4 ~]# tput cup 10 10
[root@server4 ~]#
[root@server4 ~]# tput setb n
[root@server4 ~]# tput setb 2
[root@server4 ~]# tput setb 0
[root@server4 ~]# hello
hello
[root@server4 ~]# hello
hello
[root@server4 ~]# owca
bash: owca: command not found...
[root@server4 ~]# tput setb 1
[root@server4 ~]# echo this
this
[root@server4 ~]# echo this
this
[root@server4 ~]# haha
bash: haha: command not found...
[root@server4 ~]# tput smul
[root@server4 ~]# tput rmul
[root@server4 ~]# ll
total 140288
-rw-r--r--. 1 root root 92 Jul 13 16:46 1
-rwxr-xr-x. 1 root root 339 Jul 17 13:54 addScalaHome.sh
-rwxr-xr-x. 1 root root 377 Jul 11 20:58 adjustSysctlConf.sh
-rw-------. 1 root root 1260 Jun 16 01:12 anaconda-ks.cfg
drwxr-xr-x. 2 root root 6 Jul 25 18:55 backup
-rw-r--r--. 1 root root 9 Jul 20 21:02 cal
-rwxr-xr-x. 1 root root 99 Jul 20 20:39 checkUser.sh
-rwxr-xr-x. 1 root root 115 Jul 13 17:00 checkZookeeper.sh
-rwxr-xr-x. 1 root root 155 Jul 22 17:20 closeZookeeper.sh
drwxr-xr-x. 4 root root 37 Jul 13 11:01 hadoop_temp
-rw-r--r--. 1 root root 54 Jul 4 14:11 HelloLinux.txt
-rw-r--r--. 1 root root 42 Jul 22 20:56 hosts
-rw-r--r--. 1 root root 1308 Jul 25 21:13 initial-setup-ks.cfg
-rwxr-xr-x. 1 root root 93 Jul 13 17:16 jps.sh
-rw-r--r--. 1 root root 67 Jul 25 11:24 log.txt
-rw-r--r--. 1 root root 78066230 Jul 13 17:36 opentsdb-2.3.0.tar.gz
drwxr-xr-x. 3 root root 8192 Jul 22 16:21 openTSDB_temp
-rw-r--r--. 1 root root 15 Jul 25 14:22 output.txt
-rw-r--r--. 1 root root 216 Jul 23 22:00 out.txt
-rwxr-xr-x. 1 root root 71 Jul 22 16:56 reboot.sh
-rw-r--r--. 1 root root 28678231 Mar 4 2016 scala-2.11.8.tgz
-rwxr-xr-x. 1 root root 267 Jul 13 17:01 startZookeeper.sh
-rw-r--r--. 1 root root 58 Jul 23 09:43 stderr.txt
-rw-r--r--. 1 root root 0 Jul 23 09:43 stdout.txt
-rw-r--r--. 1 root root 3497 Jul 20 19:19 temp
-rwxr-xr-x. 1 root root 138 Jul 20 14:40 test2.sh
-rwxr-xr-x. 1 root root 102 Jul 25 11:22 test3.sh
-rwxr-xr-x. 1 root root 98 Jul 20 14:41 test.sh
-rw-r--r--. 1 root root 3454 Jul 22 21:05 test.zip
-rw-r--r--. 1 root root 36670230 Jul 7 15:36 zookeeper-3.4.11.tar.gz
-rw-r--r--. 1 root root 124241 Jul 22 20:55 zookeeper.out
[root@server4 ~]# echo \\
\
输出当前日期
[root@server4 ~]# date +%s
1532525664
[root@server4 ~]# cat out.txt
HelloLinux
/root
this is third line.added in 20180704
HelloLinux
/root
this is third line.added in 20180704
HelloLinux
/root
this is third line.added in 20180704
HelloLinux
/root
this is third line.added in 20180704
Thu Jul 26 10:22:01 CST 2018
Thu Jul 26 10:23:01 CST 2018
[root@server4 ~]#
[root@server4 cron]# cat root
* * * * * /bin/echo `date` >> /root/out.txt
[root@server4 cron]#
`echo > file`【echo 12 >> file2】命令：
1.即使当前目录下没有file文件，也会自己创建一个file文件
[littlelawson@server4 test]$ ll
total 0
[littlelawson@server4 test]$ echo 12 > file1
[littlelawson@server4 test]$ ll
total 4
-rw-rw-r--. 1 littlelawson littlelawson 3 Jul 27 10:14 file1
unalias vi
问题：vi 打开文件时，蓝色字体和黑色背景导致阅读困难
原因：有时候并不是因为系统的原因，而是因为xshell的字体风格设置的原因。
解决办法：调整xshell的配色方案。
dd连敲两行
###shell脚本攻略学习笔记之六
concatenate content from input files along with standard input using cat. Combine stdin and data from another file,as follows:
echo 'Text through stdin' | cat - file.txt
cat
-s --squeeze-blank
suppress repeated empty output lines/squeeze adjacent blank lines.[压缩连续的空行]
-T, --show-tabs
display TAB characters as ^I[将TAB键展示城^I]
[root@server4 ~]# cat file.py
def function()
var = 5;
next = 6
third = 7
[root@server4 ~]# cat -T file.py
def function()
^Ivar = 5;
next = 6
^Ithird = 7
-n, --number
number all output lines【显示出行号，包括空行】
-b, --number-nonblank
number nonempty output lines, overrides -n【输出行号，不包括空行】
Recording and playing back of terminal sessions
这里的意思就是：如果需要查看过去的终端回话的的历史，那么我们可以将我们执行的命令存放到某个文件件中，以供后期查看。
[root@server4 ~]# script
Script started, file is typescript
[root@server4 ~]# echo hello
hello
[root@server4 ~]# exit
exit
Script done, file is typescript
[root@server4 ~]# ll
total 1
-rw-r--r--. 1 root root 241 Aug 5 11:59 typescript
[root@server4 ~]# cat typescript
Script started on Sun 05 Aug 2018 11:54:28 AM CST
[root@server4 ~]# echo hello
hello
[root@server4 ~]# exit
exit
Script done on Sun 05 Aug 2018 11:59:17 AM CST
script
-a, --append
Append the output to file or typescript, retaining the prior contents.【追加输出到file或者是typescript中，保留之前的内容】