How to check memory size ?? How to get total memory size ?

Solaris

1. dmesg | grep mem
2. prtdiag | grep Memory
3. prtconf -v | grep Memory

AIX

1. bootinfo -r
2. lsattr -E1 sys0 -a realmem
3. getconf REAL_MEMORY

HPUX

1. dmesg | grep Physical
2. /opt/ignite/bin/print_manifest | grep Memory
3. machinfo | grep Memory

Linux

1. dmesg | grep Memory
2. grep -i memtotal /proc/meminfo
3. free