How to create swap file in RedhatLinux Server

hello, guys today i will tell you how can we create the swap file in a Linux .swap is part of virtual part of heard disk.  basically, swap part is a system  used like RAM .so if we create swap file  or partition .if  we can increase our system swap memory step

step 1- before we create any file and then we convert in swap memory kile this 
#touch a.txt                                      (a.txt is filename )

#dd if=/dev/zero of=a.txt bs=1M count=1000

here we format swap file

#mkswap a.txt

here we will below commands through on swap

#swapon a.txt

we will check below commands

#free -m

then we will permanent swap file

# vim /etc/fstab    (note -here we will go to insert mod through (i) commands and we will save ( press Ese then press :wq)

/root/file swaps                                           swpas                         default                        0 0

:wq   (then save to swap file )

Thank you

by vishnu sharma