Adding SWAP by dd command

Create and add swap space in linux.
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#dd if=/dev/zero of=/swap1 bs=1024 count=1048576

#dd if=/dev/zero of=/dev/swap1 bs=1G count=4

#mkswap /swap1

#swapon /swap1

#free -m


bs=1024 ( 1MB )
count=1048576 ( 1GB )