Aim:

Shell script that accepts two file names as arguments, checks if the permissions for these files are identical and if the permissions are identical, outputs the common permissions, otherwise outputs each file name followed by its permissions.

Descrtiption:

-ne:not equal to.

cut -c:command to cut the specified columns from the given input.

$#: Contains the total number of input arguments.

Code:

#!/bin/sh

if [ $# -ne 2 ]
then
echo " please enter 2 arguments"
exit
fi
perm1=ls -l $1|cut -c 1-10
perm2=ls -l $2|cut -c 1-10
if [ $perm1 = $perm2 ]
then
echo "Permissions are same for both files"
echo "permissions are: $perm1"
exit
fi
str1=ls -l $1|cut -c 2-4
str2=ls -l $2|cut -c 2-4
if [ $str1 = $str2 ]
then
echo "Owner permissions are same: $str1 "
else
echo "Owner permissions are different"
echo " Permissions for file $1 : $str1 "
echo " Permissions for file $2 : $str2 "
fi 
str3=ls -l $1|cut -c 5-7
str4=ls -l $2|cut -c 5-7
if [ $str3 = $str4 ]
then
echo "Group permissions are same: $str3 "
else
echo "Group permissions are different"
echo " Permissions for file $1 : $str3 "
echo " Permissions for file $2 : $str4 "
fi 
str5=ls -l $1|cut -c 8-10
str6=ls -l $2|cut -c 8-10
if [ $str5 = $str6 ]
then
echo "Other's permissions are same: $str5 "
else
echo "Other's permissions are different"
echo " Permissions for file $1 : $str5 "
echo " Permissions for file $2 : $str6 "
fi 

Compile: ./1.sh 1.c 1.sh

Output:

Owner permissions are different
 Permissions for file 1.c : rw- 
 Permissions for file 1.sh : rwx 
Group permissions are different
 Permissions for file 1.c : rw- 
 Permissions for file 1.sh : r-x 
Other's permissions are different
 Permissions for file 1.c : r-- 
 Permissions for file 1.sh : r-x

Compile: ./1.sh a.out 1.sh

Output:

Owner permissions are same: rwx 
Group permissions are different
 Permissions for file a.out : rwx 
 Permissions for file 1.sh : r-x 
Other's permissions are same: r-x