Shell (3) application

Shell Script (iii)

A For Loop statement: (Unknown number of cycles)

For Variable name Value list
Do
Command sequence
Done

(1) Bulk add users by Name list
Vim/root/user.txt
?
Zhangsan
Wangwu
Xiaobai
vim/root/uadd.sh
#!/bin/bash
ulist=$ (Cat/root/user.txt)
For uname in $ULIST
Do
Useradd $uname
echo "123456" | passwd--stdin $uname &>/dev/null
Done
sh/root/uadd.sh
cat/etc/passwd

① Develop Employee List files

② scripting (For Loop statement format)

③ Execute Script

(2) Check host status based on IP address
Vim/root/ipadds.txt
192.168.1.1
192.168.1.2
192.168.10.1
Vim chkhosts.sh
#!/bin/bash
hlist=$ (Cat/root/ipadds.txt)
For IP in $HLIST
Do
Ping-c 3-i 0.2-w 3 $IP &>/dev/null
If [$?-eq 0]
Then echo "Host $IP was up"
else echo "host $IP is down"
Fi
Done
chmod +x chkhosts.sh
SH chkhosts.sh

① Developing IP address lists

② scripting (For Loop statement format)

③ Execute Script

Two-While loop statement: (Number of cycles known)

While condition test
Do
Command sequence
Done

(1) Batch to add a regular number of users:
① use I to control the number of user names
② in the loop by Let + + (equivalent to i= ' expr $i + 1 ') to increase I, and so on.

(2) Guess the price of the game:
vim/pricegame.sh
#!/bin/bash
price=$ (expr $RANDOM% 1000)
Times=0
echo "Price between 0 and 999 pelease input It"
While True
Do
Read-p "Input price:" int
Let times++
If [$price-eq $int]; Then
echo "Yes,you is right."
echo "You have anwser $times time"
Exit 0
elif [$int-gt $price]; Then
echo "Price was too high"
Else
echo "Price was too low"
Fi
Done
chmod +x/pricegame.sh
./pricegame.sh

① a random integer of less than 2 16 is obtained by using the environment variable random, and the remainder of the 1000 is computed to obtain a random price of 0~999.
② repeated test operations can be implemented by a while loop that ture as a test condition
③ when the user guesses the thing to abort the operation
④ using variables to manipulate the number of probabilities

Three Case Branch statements:

Case Variable value in
Mode 1)
Command sequence 1
；；
Mode 2)
Command Sequence 2
；；
......
*）
Default command sequence
Esac

(1) Keystroke type recognition (Case Branch statement format):

(2) Write the System service script (case Branch statement format):

Vim/myprogs
Case "$" in
Start
Echo-n "Zhengzai qi Dong $sleep fuwu"
If Sleep 7200 &
Then
echo "OK"
Fi
;;
Stop
Echo-n "Zheng Guan bi dong sleep fuwu"
Pkill "Sleep" &/dev/null
echo "OK"
;;
Status
If Pgrep "Sleep" &>dev/null
Then
echo "Fuwuyikaiqi"
Else
echo "Fuwuyitongzhi"
Fi
;;
Restart
$ stop
$ start
;;
*)
echo "TONGAF: $ {Start|stop|restart|status}"
Esac
chmod +x/myprogs
./myprogs Start
./myprogs Status
./myprogs Stop

Shell (3) application