待整理
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.
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。
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】
