Lesson 2.4: Processing output of shell commands within a script

Example 1: Changing the permission of folders which do not have permission 755 to 755

 
#Viewing the initial permission
[sanjeeb@server Script]$ ls folder/ -lh 
total 0
drwxrwxrwx. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d1
drwxrwxrwx. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d2
drwxr-xr-x. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d3
 
#Running the script
[sanjeeb@server Script]$ ./script4.sh 
Enter the directory
/folder/
changing ./folder/d1 permission to 755
changing ./folder/d2 permission to 755
 
#Viewing the final permission
[sanjeeb@server Script]$ ls folder/ -lh 
total 0
drwxr-xr-x. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d1
drwxr-xr-x. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d2
drwxr-xr-x. 2 sanjeeb sanjeeb 6 Apr  7 10:41 d3

Example 2: Create a shell script called delusers.sh such that when it execute, it removes the last 2 users.

 
[root@server Script]# tail -2 /etc/passwd
ram:x:1003:1004::/home/ram:/bin/bash
laxman:x:1004:1005::/home/laxman:/bin/bash
 
[root@server Script]# cat delusers.sh 
#!/bin/bash
 
for i in $(tail -2 /etc/passwd | cut -f 1 -d :)
do
	userdel -r $i
	echo "Student $userdel deleted successfully !"
done
 
[root@server Script]# ./delusers.sh 
Student  deleted successfully !
Student  deleted successfully !
 
[root@server Script]# tail -2 /etc/passwd
apache:x:48:48:Apache:/usr/share/httpd:/sbin/nologin
nginx:x:979:978:Nginx web server:/var/lib/nginx:/sbin/nologin