Example of Shell programming under Linux

1. Determine if a file is a block or character device file, and if it is copied to the/dev directory

Read-p "Input a file:" filename

If [-B $filename-O-C $filename]
Then
CP $filename/dev/

Fi

2. Write a script to perform a simple subtraction operation requiring prompt input variable


#!/bin/bash
read-p "input a number:" Num1
Read-p "input another Number: "Num2
Let" num3=num1-num2 "
Echo $num 3



3. Change the file name extension in a directory to bat, and then compress and pack the files to a directory in time.


#!/bin/bash
for file with $ (LS $)
do
New_file=${file%.*}.bat
mv./$1/$file./$1/$new _file
tmp=$ (date +%y)
tar cvf./$tmp. Tar./$1
Done

4. Determine if a number is a number. Prints the number of finishes between 1-1000. The number is twice times the number of the sum equal to itself. (6,28,496)

#!/bin/bash
Sub ()
{
I=1;
sum=0;
While [$i-le $num]
does
let "m=num%i"
If [$m-eq 0]
and
Let "sum=sum+i"
Fi
Let "i=i+1"
Don E
Let ' a=2*num '
if [$a-eq $sum]
then
Echo $num
Fi
}
num=1
While [$num-le +]
do
sub< Br>let "num = num+1"
Done


5. Find a file with a specified string under a folder

#!/bin/bash
For file in $ (LS $)
Do
bname=$ (grep-l $ $2/$file)
BaseName $bname
Done


6. Add a new group for Class1, and then add 30 users belonging to this group, with the user name in the form stdxx, where xx is from 01 to 30.

#!/bin/bash
Groupadd Class1
For i in {9901..9930}
Do
xx=$ (echo $i | sed ' s/99//');
useradd-g Class1 Std$xx-p ""
Done


7. Design a shell program, in the/userdata directory to establish 50 directories, that is, USER1~USER50, and set the permissions of each directory, its \ The other user's permissions are: Read, the file owner's permissions are: Read, write, execute, the permissions of the group of the file owner is: Read, execute.

#!/bin/bash
For ((i=1;i<=50;i++))
Do
Mkdir-p/usrdata/user$i
Cd/usrdata
chmod 754 user$i
Done


8. Write a script that calculates the factorial of 10 using a loop
#!/bin/sh
Factorial=1
For a in ' SEQ 1 10 '
Do
factorial= ' expr $factorial \* $a '
Done
echo "10! = $factorial "

9. Delete a file of size 0 under the current directory
#/bin/bash
for filename in ' ls '
Do
If test-d $filename
Then b=0
Else
a=$ (ls-l $filename | awk ' {print $} ')
if test $a-eq 0
Then RM $filename
Fi
Fi
Done