#!/bin/bash
# whocanwrite <file>
# prints users who can write to file (can  contain duplicates)

rights_string=`ls -ld $1 | awk '{print $1}'`
owner_string=`ls -ld $1 | awk '{print $3}'`
group_string=`ls -ld $1 | awk {'print $4'}`

those_can_write=""

if [ ${rights_string:2:1} = "w" ]
then
    those_can_write=$owner_string
fi

if [ ${rights_string:5:1} = "w" ]
then
    group_id=$(cat /etc/group | awk -F: "{if (\$1 == \"$group_string\") print \$3}" )
    initial_group_list=$(cat /etc/passwd | awk -F: "{if (\$4 == \"$group_id\" ) print \$1}" )
    additional_group_list=$(cat /etc/group | awk -F: "{if ( \$1 == \"$group_string\" ) print \$4"} )
    those_can_write="$those_can_write $initial_group_list $additional_group_list"
fi

if [ ${rights_string:9:1} = "w" ]
then
   those_can_write=$(cat /etc/passwd | awk -F: "{print \$1}")
fi

echo $those_can_write