Get total physical memory in Python

Using os.sysconf on Linux:

import os
mem_bytes = os.sysconf('SC_PAGE_SIZE') * os.sysconf('SC_PHYS_PAGES')  # e.g. 4015976448
mem_gib = mem_bytes/(1024.**3)  # e.g. 3.74

Note:

• SC_PAGE_SIZE is often 4096.
• SC_PAGESIZE and SC_PAGE_SIZE are equal.
• For more info, see man sysconf.
• For MacOS, as per user reports, this works with Python 3.7 but not with Python 3.8.

Using /proc/meminfo on Linux:

meminfo = dict((i.split()[0].rstrip(':'),int(i.split()[1])) for i in open('/proc/meminfo').readlines())
mem_kib = meminfo['MemTotal']  # e.g. 3921852

Regular expressions work well for this sort of thing, and might help with any minor differences across distributions.

import re
with open('/proc/meminfo') as f:
    meminfo = f.read()
matched = re.search(r'^MemTotal:\s+(\d+)', meminfo)
if matched: 
    mem_total_kB = int(matched.groups()[0])

This code worked for me without any external library at Python 2.7.9

import os
mem=str(os.popen('free -t -m').readlines())
"""
Get a whole line of memory output, it will be something like below
['             total       used       free     shared    buffers     cached\n', 
'Mem:           925        591        334         14         30        355\n', 
'-/+ buffers/cache:        205        719\n', 
'Swap:           99          0         99\n', 
'Total:        1025        591        434\n']
 So, we need total memory, usage and free memory.
 We should find the index of capital T which is unique at this string
"""
T_ind=mem.index('T')
"""
Than, we can recreate the string with this information. After T we have,
"Total:        " which has 14 characters, so we can start from index of T +14
and last 4 characters are also not necessary.
We can create a new sub-string using this information
"""
mem_G=mem[T_ind+14:-4]
"""
The result will be like
1025        603        422
we need to find first index of the first space, and we can start our substring
from from 0 to this index number, this will give us the string of total memory
"""
S1_ind=mem_G.index(' ')
mem_T=mem_G[0:S1_ind]

print 'Summary = ' + mem_G
print 'Total Memory = ' + mem_T +' MB'

Easily we can get the Used Memory and Free Memory

    """
        Similarly we will create a new sub-string, which will start at the second value. 
        The resulting string will be like
        603        422
        Again, we should find the index of first space and than the 
        take the Used Memory and Free memory.
        """
        mem_G1=mem_G[S1_ind+8:]
        S2_ind=mem_G1.index(' ')
        mem_U=mem_G1[0:S2_ind]

        mem_F=mem_G1[S2_ind+8:]
    print 'Used Memory = ' + mem_U +' MB'
    print 'Free Memory = ' + mem_F +' MB'