Question

Write a C Unix shell script called showperm that accepts two command line parameters. The first parameter should be an option flag, either r, w or x. The second parameter should be a file name. The script should indicate if the specified file access mode is turned on for the specified file, but it should display an error message if the file is not found. For example, if the user enters: showperm r thisfile the script should display “readable” or “not readable” depending on the current status of thisfile.

Answer 1

Please find the script to identify whether the file is not executbale/readable/writable.

Script:

#verify the arguments

if [ $# == 2 ]
then

#verify whether the first argument is r/w/x
   if [[ $1 == 'r' || $1 == 'w' || $1 == 'x' ]]
   then

#verify the file is present
       if [ -f $2 ]
       then
         if [ $1 == 'r' ]
         then

#verify the file is readable
              if [ -r $2 ]
              then
                echo "File is readable"
              else
                echo "File is unreadable"
              fi

#verify the file is writable
         elif [ $1 == 'w' ]
         then
              if [ -w $2 ]
              then
                echo "File is writable"
              else
                echo "File is unwritable"
              fi
         else

#verify the file is executable
              if [ -x $2 ]
              then
                echo "File is executable"
              else
                echo "File is not executable"
              fi
         fi
       else
        echo "File: $2 not found"
       fi
   else
      echo "usgae: $0 [r|w|x] <file-name>"
   fi
else
      echo "usgae: $0 [r|w|x] <file-name>"
fi

Output:

USER> sh showperm.sh x dcler
File: dcler not found

USER> sh showperm.sh x
usgae: showperm.sh [r|w|x] <file-name>

USER> sh showperm.sh
usgae: showperm.sh [r|w|x] <file-name>

USER> sh showperm.sh r reg1
File is readable

USER> sh showperm.sh w reg1
File is writable

USER> sh showperm.sh x reg1
File is not executable