about shared memory space in Linux !

Linux and Unix-Like Red Hat
1

Dear Friends ,

I am confused about shared memory in Linux . plz look @ the below output :

[oracle@report ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 126G 61G 59G 52% /
tmpfs 1.7G 0 1.7G 0% /dev/shm

Here , I see that every time Redhat Linux occupied some space (here 1.7 GB) for shared memory . Would u plz tell me , why this shared memory is used .

1) Is this area only for oracle instance or others ?
2) If I dont need this space , can I manually remove this space ?
3) Is this shared memory resides only Linux o/s or other also other unix o/s version ?

Plz explain ... ...

2

Are you running Oracle?

An Oracle database is a heavy user of shared memory. For example, shared memory is used for implementing the SGA (System Global Area) which is Oracle's structurad memory area that facilitates the transfer of data and information between clients and the database.