Bash exercises

Exer1.sh

#!/bin/bash

for INPUT in $(cat $1) ; do
        if [ $(echo $INPUT | egrep -c "^[0-9]$") -eq 1 ] ; then
                echo $INPUT >> $2
        else
                echo $INPUT >> $3
        fi
done

Exer2.sh

#!/bin/bash 

QN=0 #quantity of numbers
QW=0 #quantity of words

for L in $(cat $1) ; do
        let RES=L%2

        if [ $(echo $L | egrep -c "[0-9]+") -ne 0 ] ; then 
                let QN+=1
                if [ $RES -eq 0 ] ; then
                        echo $L >> $2
                else
                        echo $L >> $3
                fi
        else 
                let QW+=1
        fi
done

echo "Quantity of numbers: "$QN
echo "Not numbers: "$QW

Exer3.sh

#!/bin/bash

C=0
for ARG in $@ ; do
        if [ $C -gt 0 ] ; then
                if [ -f $ARG ] && [ -w $ARG ] ; then
                        if [ $(cat $ARG 2> /dev/null | wc -l) -eq 0 ] ; then
                                echo $ARG >> $1
                        fi
                fi

                if [ $(ls $ARG 2> /dev/null | wc -l) -eq 0 ] ; then
                        echo $ARG >> $1
                fi
        fi
        let C+=1
done