more flexible parsing for /proc/meminfo to take shared and reclaimable
memory into account. this matches the output with free(1).
additionally this could fix some corner cases, as the order of fields in
/proc/meminfo is not strictly defined.
slstatus:
percent 81% free 2.5 Gi total 23.4 Gi used 19.0 Gi
free(1):
total used free shared buff/cache available
Mem: 23Gi 19Gi 2.5Gi 1.3Gi 3.2Gi 3.6Gi
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