Shell Programming and Scripting

kcsdev:/home/jmcnama> cat file1 
1
2
3
4
5
7
8

kcsdev:/home/jmcnama> cat file2
9
10

kcsdev:/home/jmcnama> s.sh
 6 is missing

#!/bin/ksh
# script = s.sh
let expected=1
for i in $( cat file1 file2 | sort -n -u)
do
    if [[ $expected != $i ]] ; then
        echo " $expected is missing"
        break
    fi
    let expected=$expected+1
done

#!/bin/ksh
# script = s.sh
let expected=1
for i in $( cat file1 file2 | sort -n -u)
do
    if [[ $expected != $i ]] ; then
        echo " $expected is missing"
        expected=$i       
    fi
    let expected=$expected+1
done

$ cat 11
1
2 
3
7
8

$ cat 22
4
5
11

$ cat 11 22 | sort -n -u | ./a
6
9
10
$ cat a
#!/bin/awk -f
BEGIN {
    i = 1;
}
/^[0-9]+/ {
    while (i < $1) {
        print i;
        i++;
    }
    i++;
}