[Shell Script #1] Read/Write data to/from files using shell scripts

Shell scripts are very handful in reading or writing data to/from files.
The below shell script will take input file, which contains numbers in a column and output two files, containing these numbers in following order.
Example:
input.txt
11
22
33
44
55
66

output:
output1.txt  output2.txt
11                  22
33                  44
55                  66

Here is the script file: script1.sh

1. #!/bin/bash
2. FILENAME=$1
3. count=0
4. 
   
5. while read LINE
6. do
7. let count++
8. if [ "$count" -eq 1 ]; then
9. echo $LINE >> "output1.txt"
10. else
11. count=0
12. echo $LINE >> "output2.txt"
13. fi
14. done < $FILENAME