shell script : odd line , even line

 # cat zzz.txt

1 hello

2 hi

3 hello

4 hi

5 hello

6 hi

7 hello

8 hi

9 hello

10 hi

- 奇数  ( head -1 , -3 , -5 ... )

# head -1 zzz.txt | tail -1

1 hello

# head -3 zzz.txt | tail -1

3 hello

- 偶数 ( head -2 , -4 , -6 )

# head -2 zzz.txt | tail -1

2 hi

# head -4 zzz.txt | tail -1

4 hi

- シェルスクリプト

# cat abc.sh

#!/bin/sh

i=1

j=2

k=`wc -l zzz.txt | awk '{print $1+1}'`

echo "odd line"

while [ $i -lt $k ];

do

        head -$i zzz.txt | tail -1

        i=`expr $i + 2`

done

echo ""

echo "even line"

while [ $j -lt $k ];

do

        head -$j zzz.txt | tail -1

        j=`expr $j + 2`

done

# ./abc.sh

odd line

1 hello

3 hello

5 hello

7 hello

9 hello

even line

2 hi

4 hi

6 hi

8 hi

10 hi