A simple app to read from and output to files

23Dec09

This is a script I wrote to get in touch with some bash basics.

#!/bin/bash
#: Description	: Reads a file with entries in separated
lines and write them to a file with a comma separated format
#:	Author	: Thameera
#: Date	: 23/12/2009

while IFS= read -r name1
do
	read -r	name2
	read -r age
	if [ -z "$age" ]
	then
		break
	fi
	printf "%s %s, %s\n" "$name1" "$name2" "$age"
done

What this code does is to read from a file specified in the argument list a list with the following format:

firstname1
lastname1
age1
firstname2
lastname2
age2
....

and arrange them in the following order in a new file specified by the argument:

firstname1 lastname1, age1
firstname2 lastname2, age2

Suppose you save this file with the name main and your input is in the file in. Then the command to execute the script should be:

bash main <in >out

This will write the output in a new file called out.

When I first wrote this script, I found out that the output would produce an extra blank line with a comma. The if condition if [ -z "$age" ] was added to rectify this. This condition will break the loop when it finds that the variable age is no longer assigned to a valid value.

Well, it does not do any interesting stuff, but helped me to get touch with some basics. Hope to post some more interesting stuff in the time to come.