Ubuntu Unleashed 2019 Edition: Covering 18.04, 18.10, 19.04

called file1 and a subdirectory dir1 under the current directory. Assume
that file1 has a permission of r-x (read and execute permission) and
dir1 has a permission of rwx (read, write, and execute permission). The
code for the shell program would look like this:

Click here to view code image
#!/bin/sh
if [ -d $dir1 ]; then
echo ""dir1 is a directory"
else
echo ""dir1 is not a directory"
fi

if  [   -f  $dir1   ];  then

            echo    ""dir1  is  a   regular file"

else

            echo    ""dir1  is  not a   regular file"

fi

if  [   -r  $file1  ];  then

            echo    ""file1 has read    permission"

else

            echo    ""file1 does    not have    read    permission"

fi

if  [   -w  $file1  ];  then

            echo    ""file1 has write   permission"

else

            echo    ""file1 does    not have    write   permission"

fi

if  [   -x  $dir1   ];  then

            echo    ""dir1  has execute permission"

else

            echo    ""dir1  does    not have    execute permission"

fi

If you execute the shell program, you get the following results:

Click here to view code image
dir1 is a directory
file1 is a regular file
file1 has read permission
file1 does not have write permission
dir1 has execute permission

Logical Operators

You use logical operators to compare expressions using Boolean logic—that