I need to write a simple program called "kv" in C language. It is a simple persistent key-value store.

The program will have a few options. The first is to insert some (key, value) pairs into the database. This is accomplished as follows:

```sh

prompt> ./kv

prompt> ./kv p,10,remzi

prompt> ./kv p,20,andrea p,40,someotherperson

```

```sh

prompt> ./kv g,10

10,remzi

prompt>

```

There are many many ways to implement such a feature. Here, we suggest something very simple. The idea will be to use a single file (called, say, `database.txt`), where you store all of this information in plain-text format.

```sh

prompt> cat database.txt

1,first

2,second

prompt>

```

CFLAGS=-O2 -Wall -Werror

This is Makefile

kv: kv.c

$(CC) -o kv $< $(CFLAGS)

test: kv

bash test-kv.sh

clean:

rm -f database.txt kv

rm -fr tests-out