Add this to your .bashrc or .bash_profile to get a `free` command in OS-X. Originally found at http://apple.stackexchange.com/questions/4286/is-there-a-mac-os-x-terminal-version-of-the-free-command-in-linux-systems

free.sh

##
# How about a `free` command if we're on OS-X?
#
if [ -z "`which free`" ]; then
    freePython="
import re, subprocess
# Get process info
ps = subprocess.Popen(['ps', '-caxm', '-orss,comm'], stdout=subprocess.PIPE).communicate()[0]
vm = subprocess.Popen(['vm_stat'], stdout=subprocess.PIPE).communicate()[0]
# Iterate over all processes
processLines = ps.split('\n')
sep = re.compile('[\s]+')
rssTotal = 0 # kB
for row in range(1,len(processLines)):
    rowText = processLines[row].strip()
    rowElements = sep.split(rowText)
    try:
        rss = float(rowElements[0]) * 1024
    except:
        rss = 0 # ignore...
    rssTotal += rss
# Process vm_stat
vmLines = vm.split('\n')
sep = re.compile(':[\s]+')
vmStats = {}
for row in range(1, len(vmLines)-2):
    rowText = vmLines[row].strip()
    rowElements = sep.split(rowText)
    vmStats[(rowElements[0])] = int(rowElements[1].strip('\.')) * 4096
# Display output
print 'Wired Memory:\t\t%d MB' % (vmStats['Pages wired down'] / 1024 / 1024)
print 'Active Memory:\t\t%d MB' % (vmStats['Pages active'] / 1024 / 1024)
print 'Inactive Memory:\t%d MB' % (vmStats['Pages inactive'] / 1024 / 1024 )
print 'Free Memory:\t\t%d MB' % (vmStats['Pages free'] / 1024 / 1024)
print 'Real Mem Total (ps):\t%.3f MB' % (rssTotal / 1024 / 1024)"
    alias free="python -c "'"'$freePython'"'
    unset freePython
fi